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2020 | Book

Proceedings of the 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2019)

Volume III: Buildings and Energy

Editors: Prof. Zhaojun Wang, Prof. Yingxin Zhu, Prof. Fang Wang, Prof. Peng Wang, Prof. Chao Shen, Prof. Jing Liu

Publisher: Springer Singapore

Book Series : Environmental Science and Engineering

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About this book

This book presents selected papers from the 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2019), with a focus on HVAC techniques for improving indoor environment quality and the energy efficiency of heating and cooling systems. Presenting inspiration for implementing more efficient and safer HVAC systems, the book is a valuable resource for academic researchers, engineers in industry, and government regulators.

Table of Contents

Frontmatter
Research and Accuracy Analysis on Engineering Quantity Calculation of a Projected Building by BIM Software

Engineering quantity calculation is the premise and foundation of cost control in architectural engineering. However, the traditional calculation method of engineering quantity way by manual method is inefficient and with low precision. The calculation is faster and more accurate if Building Information Modeling (BIM) technology is applied. In this paper, the development and histories of BIM applications in engineering cost management are introduced. Based on the data of an actual building, a simulation model is established by BIM software. The engineering quantities are calculated, and then, the results of the traditional manual calculation method of engineering quantity and calculation method of BIM are compared and analyzed. The data with a relative error of more than 10% is listed, and the reason for the relative error is conducted. It is concluded that the rules of BIM calculation and manual calculation are different, causing BIM method not accurate enough for some nodes. The suggested method is that BIM method is firstly applied for the total engineering quantity calculation, and then, the manual method is proposed to check the accuracy in some key nodes.

Xinjie Xu, Yu Wang, Jinxiang Liu, Xiaolei Yuan, Jun Bao, Xuetao Chou
Parametric Study of the Impact of Venetian Blinds on Air-Conditioning Energy-Saving Potential for Residential Buildings

This paper presents a comprehensive parametric study on the energy-saving potential of venetian blinds in residential buildings. Nine parameters which may affect the energy performance of venetian blinds were selected for parametric analysis. Three values with high, medium and low levels were set for each parameter. The medium value was set according to the mainstream products on the market, while the high and low values were the theoretical upper and lower limits. Thus, a combination of 9072 cases of venetian blinds were obtained. The above cases were modeled in WINDOW software with 0°, 45°, −45° and 90° blind angles, respectively. The EnergyPlus software was used to simulate annual air-conditioning energy consumption for each case. Finally, a new index, annual energy performance (AEP), is developed for evaluating the energy-saving potential of venetian blinds.

Yutong Tan, Jinqing Peng, Dragan C. Curcija, Nianping Li, Taoning Wang, Robert Hart, Jocob Jonsson
Effect of Glazing Ratio on Thermal Comfort and Heating/Cooling Energy Use

Glazing ratio (GR) or window-to-wall area ratio is an important factor that affects thermal loads. It also has impact on thermal environment because solar radiation through windows and warm/cold window surface temperature in different seasons. In this study, GR of 30 and 100% was compared to see their impact on thermal environment and energy use. The study was performed based on a simple office model equipped with fan-coil system located in Paris. Air temperature-based thermostat control and operative temperature-based thermostat control were compared for both GR conditions. As expected, with 100% GR, the offices used more heating and cooling energy. Total heating energy increased about 140–150% and cooling energy increase 55–60%. Compared to 30% GR, thermal comfort became worse. During working hours, the air temperature change became higher with 100% GR. Statistics showed that there were less occupancy hours within ±0.7 (PMV) when 100% GR was used. Thermal conditions of north office were better than south office. The results also showed that with operative temperature control thermal comfort can be better for both north and south office. Based on the results, operative temperature control would be better to keep comfortable thermal environment for offices with high GR.

Haiying Wang, Bjarne W. Olesen, Ongun B. Kazanci
Numerical Analysis of Airflow Distribution in Data Center with Server Baffles

In this study, servers are equipped with terminal baffles to optimize the thermal environment within data center and achieve energy conservation. The data center model is established by Airpak 3.0 packages based on an actual running data center. In the original model, the rack with the highest heat load (16.98 kW) is selected as the research object, while the exhaust airflow distribution of that rack is obtained. In order to optimize the exhaust airflow distribution, the optimization models with 8-cm baffles and six different baffle angles (0°, 15°, 30°, 45°, 60°, 75°) are established based on the original model. The results show that, although the use of 0° server baffles deteriorates the thermal environment, airflow distribution and cooling efficiency are improved to varying degrees when the inclination angle of the 8-cm baffles increases from 15 to 75°. The optimum thermal environment is achieved when the baffle angle is 45°. Under this circumstance, the maximum drop of rack hotspots reaches 2.5 °C.

Xiaolei Yuan, Xuetao Zhou, Yu Wang, Jinxiang Liu, Xinjie Xu, Yuzhen Tao
Optimization Research of Insulating Layer Thickness for Rural Residence’s Exterior Wall in Northeast Severe Cold Regions Based on Life Cycle Cost

As one of the essential components of rural residence’s envelope in severe cold regions, external wall’s heat transfer consumption accounts for about 40% of total heat consumption. Thermal insulation technology for exterior wall is one important method to improve building thermal performance. Meanwhile, the increasing of insulating layer thickness also raises the construction cost. It is necessary to determine the optimal thickness of external insulating layer from the perspective of life cycle cost. This paper, selecting the composite wall structure as research object and taking life cycle cost of external wall as evaluation index, establishes the GenOpt–EnergyPlus optimization platform by coupling EnergyPlus and GenOpt software to carry out the optimization. In the analysis, three types of insulation materials were selected to analysis. Considering that the length of life cycle may affect the effective utilization rate of operation and construction cost, three types of life cycle span are set, including 10, 20, and 30 years. Through the analysis, the optimal insulating layer thickness and changing rule of external wall under different conditions were discussed, which provides a basis for the selection of insulating layer’s material and thickness.

Teng Shao, Hong Jin, Zheng Ma
Effect of Moisture Transfer on Thermal Performance of Exterior Walls in Hot and Humid Region of China

Moisture transfer in building envelopes can affect the internal surface temperature of the envelopes and the air-conditioning energy consumption. Therefore, this study aims to evaluate the effect of moisture transfer on thermal performance of exterior walls. In this study, a coupled heat and moisture transfer model was proposed. With the measured continuous outdoor climate parameters for four hot and humid regions including Haikou, Qionghai, Xiamen, and Guangdong, this model assessed the impact of moisture transfer on the inner surface temperature, the peak cooling loads, and the heat from walls. The results showed that the fluctuation range of the internal surface temperature decreased when moisture transfer is considered. The peak cooling loads were overestimated when moisture transfer is ignored. Besides, the total heat from walls was underestimated by around 4% in the cooling seasons. This study could provide basis for future studies on moisture transfer characteristics in coastal and island areas.

Lu Bai, Jingchao Xie, Yaping Cui, Jiaping Liu, Ying Ji
Energy-Saving Analysis of Low-Rise Prefabricated Building Integrating with Metamaterial-Based Cool Roof in China

The novel metamaterial-based radiative cooling film has recently been developed and reported a 110 W/m2 cooling power on a daily average. The most convenient application of this metamaterial-based radiative cooling film is to integrate with building as the cool roof. However, the cool roof has always only benefit to the top floor of the building. Since the prefabricated building, commonly lower than two-floor, has relatively higher roof area to floor area ratio, the metamaterial-based cool roof is perfectly applicable to them as renewable energy-based new cooling mechanism. In this study, the prefabricated building is modelled with EnergyPlus, and then the detailed simulation analysis has been conducted for five locations in China, including Harbin, Beijing, Kunming, Nanjing, and Guangzhou. The results show that the adoption of metamaterial-based cool roof to low-rise prefabricated building will save cooling electricity consumption by 18.7–34.8% annually.

Mingquan Ma, Kai Zhang, Saihong Tang, Lufang Chen, Xiaofeng Niu, Fei Li
Research on Dynamic Thermal Characteristics and Energy-Saving Rate of Intermittent Heating Rooms

Continuous space heating is generally adopted for buildings in cold regions of northern China. The energy consumption for space heating is very large. Since office buildings are usually not occupied during nights, intermittent space heating could be used to shorten the heating time and save energy. This present paper studies how much energy could be saved and which factors affect the energy-saving compared to continuous heating. This paper selects a typical room in an office building, adopts room heat balance method, and establishes the dynamic thermal model of the room, and studies the dynamic thermal characteristics and energy-saving rate of intermittent heating. The conclusions are as follows: (1) Compared to continuous heating, the energy-saving rate of intermittent heating is 17.9% when the preheating period is 1 h for this case. (2) The energy-saving rate reduces with the increase of preheating period. When the preheating period is 4 h, the energy-saving rate is 10.7%. The preheating period should be less than 2 h for this case.

Guoqing Yu, Hongfei Yao, Zhenye Yan
Data-Driven Modelling and Optimal Control of Domestic Electric Water Heaters for Demand Response

Electric water heater (EWH) is widely used to provide reliable and long-lasting domestic hot water to occupants in residential buildings. EWH has been widely recognized as an important source of building energy flexibility, which could benefit both the building occupants and the power system operators through various demand response (DR) programs. DR programs applied to EWHs are investigated in this paper. Optimal control strategies are developed to operate a portfolio of EWHs in order to reduce energy costs. A control-based model of EWH is developed using the data from field experiments and a statistical grey-box modelling approach (here using the CSTM-R package). The results show that the aggregated EWHs can optimize their heating schedule in order to reduce the overall cost without compromising the comfort of occupants.

Xingji Yu, Shi You, Hanmin Cai, Laurent Georges, Peder Bacher
Effect of Inlet Air Turbulence on the Cooling Performance of Solar Enhanced Dry Cooling Towers

Solar enhanced natural draft dry cooling towers (SENDDCTs) use solar energy to reheat the air coming from vertically arranged heat exchangers for tower performance enhancement. The SENDDCT produces large differences in air density between the inside and outside of the tower (i.e., the tower driving force is intensified), and therefore enhances the ventilation inside the tower for better cooling. How to efficiently introduce solar energy for reheating the air is important for a SENDDCT. This paper is to study different air turbulence regimes so as to enhance the heat transfer in the solar reheating section. The different air turbulences are achieved by changing the endothermic ground from flat to rectangular ribs. A 3-D model is developed using FLUENT 18.0 to simulate the operation of the above-mentioned SENDDCTs. The model will be validated by comparing with literature. According to the simulation, the rectangular-rib SENDDCT enhancement can go up to 13.1% by increasing the heat rejection rate of the flat SENDDCT from 133 to 149 MW, which proves that the cooling performance of the SENDDCT can be improved by intensifying the inlet air turbulence.

Rui Wang, Suoying He, Ming Gao, Yuetao Shi, Fengzhong Sun
Generalized Models for Estimation of Diffuse Solar Radiation Based on Clearness Index

The acquisition of accurate knowledge of diffuse solar radiation is essential for the conversion and application of solar energy. Nevertheless, most regions around China lack the accurate measured diffuse solar radiation. The main purpose of this study is to establish reliable models for estimating diffuse solar radiation based on the clearness index for both annual and seasonal scenarios. For this purpose, 15 existing diffuse solar radiation models, including nine existing diffuse fraction and six existing diffuse coefficient models, were calibrated for estimation of daily diffuse solar radiation. Long-term, continuously measured global and diffuse solar radiation data were utilized as calibration and validation models. Five statistical parameters such as the mean absolute error (MAE), root mean square error (RMSE), uncertainty indicator at 95% (U95), mean absolute percentage error (MAPE), the correlation coefficient (R), and a global performance indicator (GPI) were used for evaluating the performance and accuracy of the calibrated models. The results showed that the calibrated best-performing models can estimate the daily diffuse solar radiation on a horizontal surface with good accuracy for both annual and seasonal scenarios. Moreover, the calibrated best-performing models can be used for estimating the daily diffuse solar radiation in regions like Wuhan.

Zhe Song, Zhigang Ren, Qinli Deng, Xin Chen
Experimental Investigation of PCM Wallboard in Artificial Controlled Environment with Different Climate Conditions

Phase change material (PCM) combined with building envelopes is an effective approach to establish a comfortable indoor thermal environment in summer. Thermal storage performance of PCM wallboard relies on the outdoor climatic conditions with suitable temperature. In the present paper, the thermal performance of PCM wallboard under different climate conditions is experimental investigated in artificial controlled conditions. The experimental conditions are based on typical meteorological year data of five cities in Northwest China. Two valuation indexes are proposed to quantitatively describe the climate characteristics. The experimental results highlight that the PCM wallboard thermal performance is significantly affected by temperature characteristics. In the climate condition of Xi’an, the PCM wallboard can reduce 88.9% temperature accumulation value. This work could provide reference for the applicability analysis and thermal design of PCM envelopes in different climate conditions.

Yuhao Qiao, Yan Liu, Liu Yang, Jiayang Bao, Jiaping Liu
Methodology for Determining the Optimal Size for a South-Facing Horizontal Visor Based on Different Design Periods

Reasonable shading measures can reduce the solar radiation and the cooling load in summer. Due to the outdoor climatic conditions, solar elevation angles and azimuth angles change with time, and the effect of the sun shading design is closely related to the design period. To the authors’ knowledge, little research work reported in the opening literature has been made on quantitative analysis of differences in shading evaluation under different design periods. In this paper, the analysis is conducted in five typical cities in hot summer and cold winter zone of China (Nanjing, Shanghai, Wuhan, Changsha and Guilin). Firstly, different design periods are obtained according to different shading requirements. Then, performing a quantitative analysis on the sun shading effects of the south-facing horizontal visors in different design periods is based on the self-coding. Finally, according to the shading effects, the optimal sizes for south-facing horizontal visors are obtained. These results can provide references for the shading design.

Xiangrong Zhang, Yan Liu, Liu Yang, Chen Zhang, Tang Liu
Impacts of PCM Location and Thickness on Dynamic Thermal Characteristics of External Walls for Residential Buildings

The effect of PCM wall is affected by many factors. To achieve full potential of phase change material used with structural insulated panel, the present paper investigates the impacts of PCM location and thickness on dynamic thermal characteristics of external wall of residential buildings, based on numerical simulation method. First, full implicit scheme of specific heat mathematical model of phase change wall is established by using finite difference method. Then, the boundary conditions in summer and winter are obtained based on a standard residential room under free running in Xi’an through typical meteorological year data. Finally, the thermal characteristics such as internal surface temperature, decrement factor and hourly heat flux are gained for each position and certain PCM thickness under the same boundary conditions. The results show that the optimal location is the PCM layer inside of SIP external wall and the optimum thickness is 0.04 m for SIP with heat transfer coefficient of 0.45 W m−1 °C−2. The results could provide reference for engineering applications of phase change wall. The present work is a part of DeST3.0, which first introduces PCM module into DeST.

Tang Liu, Yan Liu, Liu Yang, Jiang Liu, Yuhao Qiao, Da Yan
Influence of Building Airtightness on Energy Consumption of Office Building in Chongqing

Taking office building in Chongqing as an example analyzes the effect of increasing building airtightness on energy consumption and indoor temperature. The simulation results show that the indoor temperature will increase as the airtightness level improves in summer, but reduce the comfort degree and increase air-conditioning load. In winter, it shows the opposite tendency. Furthermore, the cumulative heating load in the transitional season gradually decreases with the increase of the airtightness level, but the cooling load shows the opposite tendency. Therefore, during the transitional season, people can use the nature ventilation to take away some of the excess heating and humidity load.

Yuan Liu, Baizhan Li, Runming Yao, Xinyun Cao
Simulations on Pressure Characteristics of Low-Flow Rate Water Circulating System Based on Porous Media Model

A spherical experimental device is placed in an underground cylindrical laboratory hall, and the surface is covered with ~17,510 photomultiplier tubes (PMTs) for detecting radiation signals. Since the device is placed underground for a long time, an effective water circulation is required to remove radon and algae to ensure stable operation. In this paper, the pressure distribution characteristics of water in the PMT region are studied. The PMT areas of the device are simplified into a porous media. Two models, i.e., a vertical-flow and a horizontal-flow model, were established to obtain the coefficient of resistance using CFD. In addition, the relationship between the pressure difference and the water entry parameters in the porous media is also studied. The results show that the resistance coefficients of single-layer PMT and two-layer PMT are similar in the vertical direction. However, the resistance coefficient of two-layer PMT in the horizontal direction is smaller than that of the single-layer PMT. Another simplified 2D model was also proposed to further study the effect of the simplified porous media on the overall flow. Overall, when the water inlet velocity is smaller, and the angle of inclination of the inlet is larger, the fluid is more likely to pass through the PMT areas, and the pressure distribution in the PMT areas can be more uniform.

Yu Xue, Wenxuan Zhao, Wei Ye, Chao Wu, Xu Zhang
Annual Thermal Evaluation of Lightweight Building Envelopes Containing Phase Change Materials in Changsha

Integrating phase change materials (PCMs) into building envelopes is a promising way to reduce building energy consumption and to improve indoor thermal comfort. This paper analyzed the thermal performance of building envelopes containing PCMs under full weather condition in a hot summer and cold winter region. Two identical houses located in Changsha were built, experimented, and simulated. In the absence of HVAC in summer, installing XPS-PCM next to the wall interior surface reduced the average indoor air temperature by 1.1 °C during office hours. Moreover, the peak load was delayed by 1 h and shifted out of the office hours. The energy use intensity (EUI) in summer and whole year was reduced by 21.9% (29.7 kWh/m2) and 8.6% (22.0 kWh/m2), compared to a wall without PCMs, respectively. In winter, the XPS-PCM position has less impact on the indoor thermal comfort. It is recommended to install the XPS-PCM board next to the wall interior surface with a night ventilation of 20 ACH.

Xiaoqin Sun, Siyuan Fan, Youhong Chu, Yajing Mo, Shuguang Liao
The Effects of Green Façades on Thermal Performance in Humid and Hot Climate

Green façades have been well proven to be efficient in preventing overheating of buildings from excessive solar radiation. The effect of orientation on thermal performance of green façade in hot and humid climate is examined in the present study. Field measurement was carried out in Suzhou, on south-facing and east-facing walls, which are covered by green façades in different orients. The results show that green façades can effectively reduce temperature increment in the daytime compared with bare wall. Compared with green façades in east orient, green façades in south orient have better thermal performance in daytime and nighttime. Relative humidity under leaf layer increased significantly for green façades. And relative humidity of surrounding air could be influenced within a small distance (not exceeding 15 cm) by green façades. This study provides useful information for scientist to further investigate microclimate alteration effect of green façades.

Cuimin Li, Hui An, Kun Lu
Review on Heat and Mass Coupled Transfer of Wooden Passive House Wall in the Cold Region

In this paper four aspects were reviewed in macroscale and microscale heat and mass coupled transfer shown by the transfer process between external and internal walls of the wooden passive house. (1) heat and mass coupled transfer process of external wooden passive house wall in the cold region; (2) influences of high temperature difference on heat and mass transfer feature parameters of wooden passive house walls; (3) heat and mass transfer process of wooden wall surface in cold region; and (4) the feature of heat and mass transfer shown by coupling characteristics between internal and external of the wall. The importance of heat and mass transfer of wooden passive house wall in cold region on the research of maximumly increasing wall’s acclimatizing ability and the detail research on energy saving performance was analyzed. Finally, some suggestions were improved on current research status and developed direction.

Huifen Zou, Zhian Yue, Meimei Yin
An Experimental Investigation of Moisture Buffering Value for Composite Hygroscopic Materials under Different Air-Flow Conditions

Hygroscopic materials used in contact with indoor air can assist in dampening the peaks of relative humidity and thus moderate the variation of indoor humidity environment. Considering convective boundary air layer’s effort, a series of experiments were set up to investigate the influence of air-flow rate and orientation on moisture buffering effect of two types of hygroscope materials. One is gypsum plaster mixed up with different percentage of microencapsulated phase change material (MPCM) and another is scallop shell scrum, blending with phase change material (PCM) slurry. A large climatic chamber, equipped with a wall of fans which could provide stable air-flow rate ranged between 0 and 2.73 m/s, was used to create a well-controlled experimental environment. The results showed that the boosted air-flow rate of environment could increase materials’ moisture ab/desorption, as well as MBV of materials in practical level. In addition, the differences between vertical and parallel samples amplified when air-flow rate raised. Detailed analysis revealed that air-flow rate influenced the initial absorption stage the most, considering its effect on evaporation process.

Chengnan Shi, Huibo Zhang, Jingwen Rui, Ya Chen, Yingli Xuan, Weirong Zhang
Analysis and Improvement Recommendations on Straw Bale Building in Northeast China

Built with compressed straw as structural or non-structural walls, the straw bale building can date back to the twentieth century in Nebraska. Besides its great thermal and acoustic insulation, buildings with straw can also lead to low impact on environment and health. It was introduced into Northeast China in 1999 by Adventist Development Relief Agency (ADRA). In order to investigate straw bale buildings’ service condition in Northeast China, a survey on 25 straw bale buildings of four villages and in Tangyuan County was conducted and a straw bale house was selected to test its interior air temperature and wall surface temperature compared to a similar clay brick house. Based on an inspection of existing buildings, serious issues relating to thermal bridge and wall cracks seized our concentration. Large areas of cracks appeared on exterior plaster, and obvious dewing on interior surface of thermal bridge could be observed, seriously influencing inhabitant environment. On the basis of in-depth analysis on these serious problems, in order to accommodate the environmental conditions in Northeast China, revisions on wall construction and exterior plaster details were put forward, making recommendations for future straw bale construction design to promote references for further generalization in China.

Jingjing Yang, Yan Liu, Liu Yang
Study on the Optimization Wall Structure in Hot and Humid Climate Region Based on Analytic Hierarchy Process

It is of great significance to consider the problems of mold and mildew growth and condensation when designing walls in hot and humid climate region. In this paper, analytic hierarchy process (AHP) method was used to obtain the optimal wall structure. Taking a typical city in hot and humid climate region, Nanchang, as an example, the advantages and disadvantages of the four typical walls including brick wall, aerated concrete wall, plasterboard–fiberglass–brick wall and new-type wooden structure were ranked using AHP method. The weight coefficients of the four typical walls were 0.0573, 0.4215, 0.1489, and 0.3723, respectively. The results indicate that the aerated concrete wall has the best comprehensive performance among the four kinds of walls in hot and humid climate region.

Xingguo Guo, Shiwei He, Yue Wu, Ying Liu, Xiangwei Liu
Energy Efficiency Analysis of Hybrid Heat Pump System-Based Air Source Auxiliary Ground Source in Chengdu Plain

The hybrid heat pump system of air source auxiliary ground source is one important approach to solve the imbalance problem of soil heat absorbing and releasing for ground source heat pump. Meanwhile, this is also one effective way for achieving high-efficient utilization of renewable energy, especially in poor areas of renewable energy. As to the problem of renewable energy applied in Chengdu city, the energy consumption of hybrid heat pump system of air source auxiliary ground source was simulated by EnergyPlus in the present study. Moreover, variation characteristics of hourly energy efficiency, power consumption and heat absorbing and releasing of underground pipe were analyzed. The differences of this system operation under different load matching conditions were obtained. The research finding provides the meaningful guidance and bases for the design and engineering application of hybrid heat pump system of air source auxiliary ground source in poor areas of renewable energy.

Jun Wang, Xiangyu Chen, Chengjun Jing, Hao Liang
Application of Combination of Relay-Pump Station and Intervals-Pressure Heat Exchange Station in Long-Distance Central Heating with Large Height Difference

When the heating pipelines have a large height difference on the way of laying, which is lead to increase the resistance of heating network and make hydraulic regime complicated. This paper presents a feasibility study of the long-distance heating pipeline project from Yangcheng Power Plant in Shanxi Province to Jincheng city which is carried out through the comparative analysis of the hydraulic pressure diagram. According to the optimal route, the following four schemes are proposed: (1) First-stage pressurization of the first station. (2) Multi-stage pressurization of relay-pump station. (3) Setting up intervals-pressure heat exchange station. (4) Combination of relay-pump station and intervals-pressure heat exchange station. The advantages and disadvantages of them are analyzed, respectively. As a result, only Scheme 4 meets the requirements of hydraulic conditions and the optimal location of the relay-pump station is determined be 9550 m away from the first station. This paper is intended to contribute a solution to the long-distance central heating with large height difference.

Huifen Zou, Mingyuan Li, Huameng Xu
Research on Behavior Pattern Prediction at Early Stage of Design

Occupant behavior has great impact on building energy consumption. Lots of efforts have been contributed to bridging the gap between simulated energy performance and the reality. Nevertheless, the prediction of potential behavior pattern in a to-be-built building is lack of researches. This study presented an approach to predict the probability of certain behavior pattern basing on available inputs at design stage. Five hundred and forty-six questionnaires about energy-related behavior preference were collected by online survey, from which the control pattern of air conditioner was analyzed and used as data source of this research. A feed forward neural network model with two hidden layers was built and trained to calculate the probability of certain behavior pattern, where the pattern “turning on air conditioner when feel hot” was taken as an example. As result of this research, the trained ANN model was cross-tested by 100 randomly selected “testing group” and reported average correct rate of 61%.

Panyu Zhu, Da Yan, Hongsan Sun, Chenxi Gui
Study on Feasibility of Accumulating Solar Energy into Soil for Improving the Imbalance of Heat Injection and Extraction in GHP System

Geothermal heat pump system (GHP) is efficient to utilize renewable energy in cooling and heating of building. However, the major problem is that the coefficient of performance (COP) of GHPs will decay after a long-time operation because of the imbalanced energy injection into and extraction from the ground. It is an effective way to apply solar collectors in the GHPs to collect thermal energy in the non-heating season and deliver the heat into ground, which may relief the imbalance. In our research, a demo project of solar-assisted geothermal heat pump system (SAGHP) in a rural building in Xi’an was built up, which delivers hot water from solar collector into soil from September 1 to November 14, 2018. For analyzing the effectiveness of elevating the ground temperature, a TRNSYS model was established, verified by the measured data in the project, and served for simulating three systems, which including the SAGHPs without accumulating solar energy in soil, the SAGHPs with accumulating thermal energy in soil in summer, and the SAGHPs with accumulating thermal energy in soil in autumn. The comparison of systems showed the significance of thermal storage in Xi’an and the feasibility of thermal injection in autumn for solar collection for improving the heat imbalance of GHPs.

Kai Liu, Nan Wang, Wanlong Cai, Xinke Wang, Fenghao Wang, Bo Xiao
Study on Extraction of Middle and Deep Geothermal Energy Through Abandoned Oil Wells

This paper research the deep geothermal energy in injection and production of abandoned oil wells. A mathematical and physical model of heat transfer in abandoned oil wells is established by retrofitting the abandoned oil wells. The effects of circulating water flow, abandoned well depth, outer tube diameter and thermal conductivity, central tube diameter and thermal conductivity on nominal heat transfer of heat exchanger were studied by numerical simulation. The results show that the nominal heat of the renovated abandoned well heat exchanger will increase with the increase of circulating water flow, borehole depth, outer pipe diameter and thermal conductivity of the outer pipe; it decreases with the increase of the diameter and thermal conductivity of the central pipe.

Guoxin Jiang, Yi Man, Tiantian Du, Shuo Li, Xinyu Zhang
Research Status and Consideration on the Relationship between Natural Ventilation and Energy Consumption of Residential Buildings

Natural ventilation is an important way to bring about energy-saving benefits. So one aim of this paper is to focus on the relationship between natural ventilation and energy consumption of residential buildings in China and other zones; list many studies based on this relationship and present a varieties of factors which are closely related to natural ventilation and affect energy consumption, such as ventilation strategies, climatic conditions, window parameters. Another aim is to provide some consideration by analysis and summary of relative researches, it is found that most studies are to evaluate the energy consumption about natural ventilation in residential buildings from only one or two factors, few people combined three, four or more factors to study, we need to form a system in order to guide building design in the future. In addition, the energy-saving economy index is introduced to evaluate the economic of energy-saving design about natural ventilation in residential buildings.

Zhipeng Huang, Ge Song, Guoqiang Zhang
Principal Factors Affecting the Accuracy of Real-Time Power Monitoring Data in Large Public Buildings

Building energy monitoring system is an effective measure to provide the energy consumption information in large-scale public buildings. However, in actual operation process, many errors may occur in the existing measurement due to the low accuracy of the instruments and mistakes in human operation. This study proposed a novel method to improve the accuracy of power monitoring data at a low instrument cost. In this method, two sets of comparative data, obtained by conventional and high-precision instruments, respectively, were measured on a self-designed test rig. The changes of the relative differences between the two sets of data were quantitatively studied considering three factors, including load rate, cable cross-sectional area, and its length on the secondary side. The results show that the measurements should be carried out under recommended conditions in engineering applications when the load rate is at more than 20%, the cable cross-sectional area at 4 mm2, and the length of cables less than 50 m. The method proposed in this study can effectively achieve the accuracy of energy consumption data through background processing based on the existing ammeters in large public buildings.

Jialin Wu, Zhuling Zheng, Zhiwei Lian, Dayi Lai
Experimental Study on a Capillary Radiant Heating Bed System Based on Solar and Air-Source Heat Pump Dual Heat Source

The traditional Chinese Kang heating system can effectively utilize the waste heat of cooking for heating and has been widely used in rural areas. However, this system may cause severe air pollution since it is heated by directly burning coal and biomass fuel. The promotion and utilization of clean heating technology are therefore attracting more and more attention. In this research, a capillary radiation heating terminals was proposed to reform the traditional Chinese Kang system. Both air-source heat pump and solar energy were used as heat source for the system. An experimental bench was set up, and a series of tests were conducted to validate the feasibility of the system. The experimental results have shown that when the temperature of the supplied water reaches to 40 °C, the indoor air temperature can satisfy the thermal environment need of residents. The solar energy can be used for about 3.5–4.5 h per day when the daily average solar radiation is greater than 2000 Wh m–2 d–1. These results may lead to the development of designing and distributing the solar energy for building heating during winter.

Xiaoyu Zhu, Xilian Luo, Juan Li, Junwei Su, Zhaolin Gu
Numerical and Experimental Study on Combustion Performance of an Infrared Radiation Burner with Porous Metal Plaque

Compared with atmospheric burner, porous infrared radiation burner has higher thermal efficiency. In this study, an infrared radiation burner with metal plaque was studied experimentally and numerically. The experimental results show that the thermal efficiency is 60.6% without blow-off, flashback, or lifted-flame during the continuous combustion for 60 min. The simulation with suitable kinetic parameters of chemical reaction agrees well with the experimental results. Moreover, a parametric study concerned with the plaque porosity, bore diameter, and thermal load was conducted by the validated model. The results show that the flame temperature increases when the bore diameter or the thermal load increases but decreases with the enlarged porosity. The upper surface temperature increases linearly with the improved thermal load but decreases when the porosity increases, and the bore diameter has a negligible effect on it. The nitrogen oxide (NOx) emission is positively correlated to the combustion temperature.

Yunfei Jia, Weiguo Zhou, Junying Tang, Yang Luo
Vent Effect Study on the Performance of Trump Wall

Trump wall is a kind of building envelope structure that can make full use of solar passive heating. The vent structure and its influence on the heating performance of the wall can be further optimized. In this paper, a laboratory bench was built in Lanzhou, China. The ventilating holes with different shapes and different inclination angles were studied by experimental methods. The result showed that the heating performance of the Trump wall was better with round ventilating hole and the venting angle of 30°. It provides a reference for the promotion and application on the Trump wall.

Yunzhi Wang, Wenhen Zhou, Xiaowei Wang, Shicheng Li, Huanying Ouyang
The Air Distribution Design in Summer of a Large Space in Lanzhou

More and more HVAC designers are facing challenges to reasonably design airflow in more and more large spaces, and the combination of design specifications and numerical simulation technology could be an effective method to deal with them. The children’s playground in Lanzhou involved in this paper is 9412 m2 and 20 m high, in which how to aesthetically furnish the air ducts and tuyeres is one of the design challenges. Firstly, the paper gives the preset design of air distribution in the children’s playground, and then, based on numerical simulation results, the scheme of 9 mushroom-shaped air columns along the floor with 1.8-m diameter and 4 m high is determined. The air supply volume of each column is 36,000 m3/h which is discharged from 36 spherical nozzles arranged along the ringside of the mushroom cap with the speed 6.7 m/s and the temperature 16 °C. Nine shutter air outlets are scattered at the sidewalls and 0.3 m high from the floor. In addition, we believe that it is more reasonable to divide the solar radiation on the transparent skylight into the roof heat flow and the internal heat source during numerical simulation.

Xiaofei Han, Wenhe Zhou, Lixin Zhao, Xin Bao, Lu Zheng, Xiaowei Wang
A Household Heating System of Solar Photovoltaic-Heating Collector Assisted by Air Source Heat Pump

The rural houses are extensive in north China, whose heating demand is needed to be satisfied, and how to reduce the environmental pollution caused by heating facilities needs to be solved urgently. The abundant solar energy resources and solar photovoltaic-heating collector could provide ideas for this problem in northwest China. In this paper, a new household heating system of solar photovoltaic-heating collector assisted by air source heat pump is introduced firstly, and then, as a practical example, this household heating system is used in a farmhouse located in Lanzhou area and tested between February 1, 2018, and March 31, 2018. The results show that the heating system is feasible and the solar photovoltaic-heating collector mentioned in this paper can convert solar energy more efficiently. During the test period, the outdoor daily minimum temperature is between −14.5 and 10 °C, the indoor daily minimum temperature is between 14.3 and 16.1 °C, the conversion efficiency of solar photovoltaic-heating collector is between 0.4 and 0.7, and the operating cost of the heating system is about ¥552 per month according to the peak–valley electricity price implemented in this area. The household heating system of solar photovoltaic-heating collector assisted by air source heat pump in this paper could be a reference model to the rural clean heating project carried out in Chain.

Shicheng Li, Wenhe Zhou, Xiaofei Han, Shiwen Ding, Shengbin Li
Changing Trend of HVAC Outdoor Air Design Conditions over the Past Half Century in China

Based on the meteorological data from 1952 to 2014, the changes of outdoor air design conditions in Beijing, Guangzhou, Haikou, Lhasa, and Shanghai were analyzed. The four parameters which are outdoor design temperature for heating, outdoor design temperature for ventilation in winter, outdoor design temperature for air conditioning in winter, and outdoor design average daily temperature for air conditioning in summer were calculated for each city with statistical 30 years and sliding one-year incremental method. Then, the trend of 60 years’ data of each city was analyzed respectively. The results show that over the past half century, the partial outdoor air design conditions for heating ventilation and air conditioning of civil buildings in China have been significantly increased, and the growth trend of conditions in each climate region has different characteristics.

Shangyu Wang, Honglian Li, Kailin Lv, Qimeng Cao, Liu Yang
Numerical Study on Flow and Thermal Characteristics in Flow Channel of Transpired Solar Collector

At present, it is urgent to improve indoor air quality while improving indoor thermal environment in winter, which is the ultimate goal in the field of architectural environment. The transpired solar collector (TSC), a solar energy integration technology in buildings, was proposed, which usually consists of a heat collecting plate with infiltration holes, an air layer, an insulation wall, an air outlet, and other auxiliary devices. In this paper, the physical models of transpired solar collector were developed, and the model is simplified to facilitate the simulation calculation and be verified through experiments to improve the reliability of the simulation results. By using numerical simulation to carry on the comprehensive and multi-case study of transpired solar collector, such as solar radiation intensities, fan suction speeds, infiltration hole non-uniform distribution up and down, and infiltration hole diameters for flow and thermal characteristics in flow channel of transpired solar collector were analyzed. The results show that the height ratio has the most obvious influence on the flow and thermal characteristics in the air layer compared with other key design and operation parameters. The results can lay a foundation for the large-scale processing and application of transpired solar collector, which is instructive.

Qian Gao, Dengjia Wang, Yanfeng Liu, Yingying Wang, Yuan Liu, Jiaping Liu
Experimental Investigation on Thermal Performance of Solar Photovoltaic System Integrated with Fins-Enhanced Phase Change Materials

The rise in the temperature of photovoltaic (PV) leads to decrease in the solar to electricity conversion efficiency, therefore, the thermal management of PV becomes important to improve PV power generation. In this paper, paraffin wax with melting temperature of 41 °C was chosen as PCM and was filled into an aluminum rectangular vessel in which vertical fins were used to improve the heat transfer performance. The fins-enhanced PCM system is integrated with PV to moderate its temperature rise and the thermal performance of the developed PV/PCM system at different inclination angles was studied experimentally. It was found that the fins-enhanced PCM system has a good cooling effect on PV. When compared to the PV system without PCM, the addition of the fins-enhanced PCM system to the PV system can reduce the solar-induced temperature rise by about 13 °C at the inclination angle of 60°, and the peak temperature of PV is delayed about 75 min. The temperature drops of PV would lead to a great increase in solar to electrical conversion efficiency.

Yong Li, Ningjing Zhao, Hao Li, Chen Zhang, Yingzhen Hou, Jiale Hu, Wang Song, Yanfeng Liu
Comparative Study of Building Energy Use Prediction Based on Three Artificial Neural Network Algorithms

With the advent of the era of big data, artificial neural network (ANN) algorithms have been widely used in the field of building energy data analysis. In order to effectively use ANN algorithms to predict building energy consumption, the data-driven building energy consumption prediction with three typical ANNs: Backpropagation neural network (BPNN), generalized regression neural network (GRNN), and fuzzy neural network (FNN) were studied. The simulated data of an office building model setup by EnergyPlus is presented for a case study. The BPNN algorithm with different hidden layer numbers, GRNN algorithm with different scatter constants, and FNN algorithm with different evolution times were investigated, and the optimal parameters of each neural network algorithm for building energy consumption prediction were finally obtained. The results show that the MSEs of all ANN-based models are almost the same with very small values. But the operation time is very different, which of GRNN has the smallest value. So, the GRNN is highly recommended for building energy consumption prediction due to its both good prediction accuracy and short operation time. This study helps to guide the selections of ANNs and the determinations of related parameters of their algorithms in engineering application.

Zhi Zhuang, Ziyu Peng, Weipeng Guo
Parametric Building Energy Modeling Based on Engineering Method and Data Monitoring

To improve building energy performance and achieve energy conservation, it is significant to predict the energy use in buildings. However, either elaborate engineering methods or simplified statistical methods have their own disadvantages which limit their application. Therefore, this paper presents a new parametric modeling approach to predict building energy based on the combination of engineering method and data monitoring. A reference office building is set up for building energy simulation by parametric analysis. The key influential variables of total energy and sub-level energy can be screened with the optimal subset regression. Then the parametric building energy model is well formulated with regression of the key variables. The established model to predict the building energy consumption has the advantage of considering the main factors and requiring limited parameters input. In the end, the effectiveness of the proposed approach is verified by a real office building.

Zhi Zhuang, Weipeng Guo
Approximate Bayesian Computation in Parameter Estimation of Building Energy Models

Model calibration is a necessary step to create reliable energy models in building retrofit. Bayesian computation in model calibration has attracted more attention because it can make full use of prior knowledge on building parameters. However, the likelihood function is hard to be computed in Bayesian computation due to the complexity of building energy simulation models. Approximate Bayesian computation (ABC) is a likelihood-free method to infer unknown parameters in complicated computational models by approximating the likelihood function with simulation. The ABC method is inherently computationally intensive since a large number of simulation runs are required to find reliable inferred values. This paper proposes a method for combining the ABC technique and the machine-learning method to compute unknown parameters in parameter estimation of building energy models. The results show that this method can provide reliable estimations of unknown parameters when calibrating building energy models.

ChuanQi Zhu, Wei Tian, Pieter de Wilde, Baoquan Yin
Sensitivity Analysis of Building Energy Performance Assessment Based on Machine-Learning Models

Variance-based sensitivity analysis in combination with machine-learning techniques has been increasingly applied in energy analysis of buildings in order to reduce computational cost of running a large number of energy models with sufficient accuracy. This paper compares the performance of two sensitivity analysis methods based on machine-learning models for building energy assessment: multivariate adaptive regression splines (MARS) and Cubist (CB). An office building located in Tianjin, China, is used as a case study with the EnergyPlus simulation program, to study the characteristics of these two sensitivity analysis methods. The results indicate that sufficient sample number is required to obtain reliable sensitivity analysis results in building energy assessment and subsequent HVAC system design and sizing. It is recommended to use at least two machine-learning models for variance-based sensitivity methods to allow the comparison of ranking results. The consistency of results from these learning methods should be thoroughly checked since the parameters in tuning these machine-learning models have significant influences on ranking results.

Wei Tian, Jiaxin Shi, Pieter de Wilde, Yu Sun, Chuanqi Zhu, Baoquan Yin
Performance Analysis of Indirect Natural Circulation PVT System for Domestic Hot Water

In this paper, the performance of an indirect natural circulation PVT system for domestic hot water with refrigerant as the circulating working medium was discussed and analyzed experimentally, including thermal performance, photovoltaic performance, overall efficiency, responding speed, heat exchange state, and temperature distribution at different positions. The influence of different five radiation intensities was tested. The results indicate that the performance is largely influenced by radiation intensity. The response speed of the system is greatly improved. It can complete the start-up within 5 min and maintain stable operation at relatively high efficiency. The superheat degree stays between 3 and 4 °C, which is not affected by the radiation intensity, but the sub-cooling degree of the liquid medium increases with the increasing of radiation intensity. Furthermore, the temperature of the panel all reaches the superheat range, but the superheat degree in the middle of the panel is the largest. The temperature distribution is not uniform, which needs to be optimized further.

Zhen Guo, Ruobing Liang, Jili Zhang, Ahmad Riaz
Parametric Study of an Earth–Air Heat Exchanger System for Heating and Cooling a Memorial

The use of an earth–air heat exchanger (EAHE) system to heat/cool the air is a passive way to meet the ventilation and thermal comfort of a building. The system uses geothermal energy by burying different combinations of pipe networks to certain depths below the building. Due to different geographical and climatic conditions, the influencing factors and applicability of EAHE systems need to be studied. In this paper, the influencing factors of the EAHE system are explored in depth by consistent theoretical analyses and scale model experiments. The experimental results show that the most reasonable pipe depth for this project is 4 m. The use of longer pipes, smaller diameters, and lower air velocities can effectively improve the thermal performance of the EAHE system.

Yujiao Zhao, Pengfei Tao, Gaihong Hao, Changfa Ji, Lang Liu
Suitability of Inlet Wind Speed for Tunnel Wind System

By setting up the tunnel inner wall heat transfer coefficient and heat transferring quantity of the theoretical model, the influence of inlet wind speed, tunnel diameter and soil types are analyzed. Furthermore, the variation of indoor temperature basing on different inlet wind speed is studied. The results show that the inlet wind speed has the maximum impact on system performance, and the indoor temperature gets higher with the accelerating of inlet wind speed. When the speed is 1 m/s, the temperature is the lowest. When the speed is less than 2 m/s, the range of air flow speed at 1.5 m of the tunnel is 0.31 to 0.37 m/s, the consequence conforms to the requirement of body thermal comfort. Therefore, if the requirements of indoor thermal environment are loose, to meet the requirement of thermal comfort, the speed of inlet wind should be controlled between 1 and 2 m/s and the heat pressure of solar chimney must be enough for providing power at the same time.

Liang Wang, Jiazheng Wang, Lin Jiang, Rubing Han
Effect of Thermal Mass on the Cooling Load of a Well-Insulated Office Building with Radiant Cooling System

The effects of thermal mass on the indoor environment and energy consumption of convective air systems (CASs) have been well studied. Few research refers to the corresponding effects in the zone with radiant heating/cooling system. This article aims to study the effects of thermal mass in external walls on the transmission load and energy performance in the spaces with active cooling surfaces, compared with those in identical rooms equipped only with equivalent CASs. This study is based on the investigation of energy performances in an assumed typical office building using the EnergyPlus simulation software. The weather conditions in four typical days during the cooling season in two cities (i.e., Beijing and Nanjing) are considered. The inside massive layer has positive effects on indoor temperature performance and instantaneous transmission load, but little impact on energy consumption. The peak cooling load in the zone with heavyweight can be shifted in a proper operation strategy. Although the cooling surface reduces the effect of thermal mass to radiation heat transfer and enhances the conduction heat gain, a structure with an inside massive layer is recommended in the zone with cooling surface.

Rong Hu, Jianlei Niu
The Feasibility Study of Net Zero Energy Building for Future Energy Development

The concept of net zero energy building has attracted many attentions and controversies since it was put forward. Many scholars have analyzed its configuration, technology, modeling approach and feasibility of application. However, there are still few studies focus on the application of net zero buildings considering future energy development. Based on the current energy situation and the development trend of energy technology, this paper analyzed the technical feasibility of net zero energy building in the hot summer and warm winter climate zone in China through case studies of two demo projects. Simulation and real-site measurement are used to obtain energy consumption data of the case buildings. The results show that the realization of net zero energy building should not only depend on the traditional energy-saving technologies, but should also depend on the transformation of the energy system and the combination of information technologies. The achievement of net zero energy building should not be conducted in an individual building, but should be conducted in scale of a whole urban energy system. In summary, net zero energy buildings are one of opportunities for the construction industry to undertake country-wide energy revolution and further integration with information technology.

Yutong Li, Bin Hao, Qing Ye
Effect of Uncertainty in the Hygrothermal Properties on Hygrothermal Modeling

Building envelopes are subject to the transient climate conditions. Moisture transfer which is coupled with heat transfer is an important issue in the field of building science. The moisture transfer and accumulation within building envelopes can lead to poor thermal performance, metal corrosion, wood decay, structure deterioration, microbial and mold growth. It is of great significance to investigate the hygrothermal behavior of building envelopes to improve the building energy efficiency, service life of buildings and indoor comfort. Though a lot of works have been done on the hygrothermal behavior of building materials, the experimental investigation is relatively lack. The hygrothermal properties of commonly used building materials which are the foundation of hygrothermal modeling often show a great uncertainty in the existing literatures. It may lead to significant discrepancy in the numerical results. In this paper, the local sensitivity analysis (LSA) method is used to investigate the effect of the uncertainty in hygrothermal properties, including the thermal conductivity, sorption isotherm, water vapor permeability and liquid water permeability, on the hygrothermal modeling. The results show that the uncertainty in the sorption isothermal and vapor permeability can lead to pretty high discrepancy in the distribution of the moisture content. The uncertainty in the sorption isothermal and vapor permeability causes relatively high error in temperature. These two properties must be determined accurately. The error caused by the uncertainty in liquid water permeability is limited since the relative humidity of the outdoor atmosphere is usually lower than 95% under which the capillary conduction is extremely weak.

Xiangwei Liu, Ying Liu, Xingguo Guo, Na Luo, Guojie Chen
Optimized Analysis of Operational Strategy Based on Different Optional Energy Supply Technologies in a Distributed Energy System of Buildings in Tianjin Eco-City during Cooling Season

This paper focused on the analysis and optimization of operational strategy of No. 2 energy supply station, which is a distributed energy system, in Tianjin Eco-city, Tianjin, China. Due to the Chinese relevant policy of electrical transmission and distribution, the CHP and PV system cannot be allowed to use right now. However, with the Chinese electrical power reform, the permit of connection between distributed generation and utility is gradually released. Thus, by using the mixed integer linear programming (MILP) analyzed the operational strategy of this energy system in Tianjin Eco-city after the connection between utility and this distributed generation is permitted. Then the comparative analysis between this optimization strategy and the baseline operational strategy had been done by analyzing two factors which included economic efficiency and energy consumption.

Zhengrong Li, Han Zhu, Zhe Tian, Wei Feng
Thermal and Flow Characteristics of Liquid-Flow Window with Different Design Configurations

Window glass occupies a great deal of the building facade, and the increase in space thermal load has given much pressure on the global environmental issues. Liquid-flow window (LFW) is an innovative concept that involves a controlled flow of liquid, just like water, within the cavity between the two glass panes. The direct solar heat transmission is weakened, whereas the visible light transmission is not affected and the indoor thermal environment is improved. In this paper, its thermal characteristics are investigated with the use of a mathematical model and numerical simulation. The effects of LFW configuration, the layer of thickness, baffler length and water flow velocity on the heat flow are analyzed. The results indicate that the design configuration and the inlet flow velocity would affect the localized water and temperature distribution. A water layer of thickness around 10 mm, glazing height-to-width ratio (GHTWR) around 0.88, baffle length-to-glazing height ratio (BLTGHR) around 0.6, and inlet flow velocity around 1.0 m/s are desirable.

Jishun Zhang, Chuanhui Zhou, Min Chen
Experimental Study of the Effects of Internal Non-structural Thermal Mass on the Thermal Inertia of the Whole Building

The thermal inertia of a building plays a pivotal role in the load curve and peak load of the air-conditioning system. Many studies have been conducted on the transient thermal behavior of building envelopes and partitions. However, it is unclear how to precisely describe the cooling storage effects of internal non-structural thermal mass such as furniture and floor laying. A series of experimental studies are conducted in this paper. Eight different experimental situations are tested, which have different distribution densities of furniture and different types of floor laying. Through these experiments, the study obtains the variations of the entire thermal inertia of the buildings under the variations of non-structural thermal mass.

Weilin Li, Jiayin Zhu, Ruixin Li, Baisong Ning
A Study of the Impact of Interior Envelope Structure on Cold and Hot Load in Yangtze River Basin of China

The climate in the Yangtze River basin in China is hot in summer while cold in winter, and humid yearly. The operation mode of heating and air-conditioning of residential buildings in this region is intermittent and air conditioners are used in the part of rooms. Most of the existing researches focus on the design of external envelope structures such as external wall, roof, external window, and natural ventilation of air infiltration. Little research paid attention to the impact of interior envelope structure on HVAC energy consumption. For this purpose, this paper did a literature review of the research toward interior envelope structure. Then a typical building model was selected according to the questionnaire survey results and relevant standards. The impact of interior envelope structure on heating and air-conditioning load and the heat transfer energy of each surface of room were discussed by simulation software EnergyPlus. With the analysis, this paper proposed that heat transfer through interior enclosure and the operating performance of air conditioner between rooms which have different operating schedules and temperature settings should be emphasized and finally indicated the further work.

Xiaofang Deng, Wei Yu, Xiangzhong Meng
Energy, Economic and Environmental Analysis of Flue Gas Heat Recovery for Coal-Fired Heat-Only Boilers

District heating in China is growing very fast, but the heat production is still and will be mainly based on coal in the near future. Therefore, it is necessary to improve the efficiency of coal-fired heat production; one important way for this is to recover the waste heat in the flue gas. This paper analyzes the influencing factors for flue gas heat recovery and proposes the use of a flue gas scrubber to recover the flue gas in a coal-fired heat-only boiler after desulfurizer. We apply this technology to a heat-only boiler in Dalian city and discuss the feasibility from the perspectives of energy, economy and environmental aspects. The results show that the maximum heat recovery rate is about 7% if the flue gas can be cooled down to 39 ℃, and the payback time of the scrubber system is about 4 years.

Yang Han, Haichao Wang, Lin Duanmu, Xiangli Li, Illka Haavisto
Performance of Repeated Cross Validation for Machine Learning Models in Building Energy Analysis

Machine learning models have been widely used in building energy assessment to provide fast and reliable energy estimation. To validate these machine learning models, the cross-validation technique has been often used to estimate model accuracy. However, most cross-validation methods are used without repetition to have only one value that may have large variations due to different sampling seeds. Therefore, this paper applies repeated cross validation to provide reliable model accuracy with small variations. An office building with ten input variables is used as case study to demonstrate the performance of cross validation in building energy analysis. The results indicate that repeated cross validation can have stable results with sufficient sampling data available and medium fold number (ten in this case). At least 200 sampling number is required to obtain reliable model accuracy estimation. Ten times of cross validation is recommended to reduce the variations of model accuracy.

Xiangfei Li, Baoquan Yin, Wei Tian, Yu Sun
Simulation Study on Ventilation System in High-Temperature Accumulation Area of Power Cabin in Underground Comprehensive Pipe Gallery

The integrated pipe gallery body is located underground and is a closed structure. Due to the poor air circulation in the power cabin, in the absence of ventilation, the large amount of heat radiated from the cable will cause the ambient temperature in the cabin to rise sharply. So, we need eliminate the high-temperature air gathering area, timely eliminate the heat dissipation of the cable, ensure the safe and efficient operation of the power cabin, and provide a good maintenance environment for the maintenance personnel. This paper takes the power cabin of an underground integrated pipe gallery in Shenyang as the research object, basing on the study of the structural characteristics of the powerhouse of the pipe gallery, determining typical conditions in numerical simulations in combination with local climatic conditions in Shenyang, uses The Fluent simulation software to study the ventilation and heat dissipation of the power cabin.

Hongwei Wang, Pengfei Dai, Wenhua Che
Research on Suitability of Solar Energy Utilization in Public Institutions Across the Country

This paper studies the suitability of solar energy utilization in public institutions across the country. The energy consumption of typical building is simulated by DeST, and the energy consumption per unit area of three public institutions in 32 provincial capitals and major cities nationwide are obtained. The energy consumption data is combined with the resources, climate, and economic data obtained from the survey. Principal component analysis and fuzzy cluster analysis are used successively. The MATLAB programming simulation is used to divide the country into ten regions of different appropriate degrees. Forming a map of suitability for solar energy utilization in four different types of public institutions and developing suitability software for solar energy utilization in public institutions across the country as a renewable and clean energy source, solar energy is of great significance to China’s economic development and environmental protection. This research provides a theoretical basis for the rational use of solar energy in public institutions across the country.

Yu Shui, Bai Lu, Feng Guohui
Energy Consumption Investigation and Analysis on Coach Stations in Tianjin

Coach station has the characteristics of high-density passenger flow, long operation time, large number of energy-consuming equipment and so on, which leads to the problem of high energy consumption. Based on the field investigation of six coach stations in Tianjin, the general building information such as architecture overview, major energy-consuming equipment, energy construction and consumption was obtained. The total energy consumption and sub-item energy consumption of each coach station were analyzed and calculated according to the investigation data. The results showed that the annual total energy consumption per unit area of the coach stations in 2017 ranged from 41.55 kWh/(m2·a) to 128.08 kWh/(m2·a), with an average of 76.53 kWh/(m2·a). The heating, ventilation and air conditioning (HVAC) system were the main component of building energy consumption, accounting for an average of 68.26% of the total energy consumption, indicating that the HVAC system of this type of buildings had a great potential for energy saving and reconstruction. Analyzed by the statistical software SPSS, the air conditioning form and heating form were significantly related to the total annual power consumption per unit area.

Xuejing Zheng, Boxiao Xu, Leizhai Sun, Dehui Kong
A Study on the Design of Waste Heat Utilization System for University Baths in Severe Cold Regions

The reduction in energy reserves in recent years has made waste heat recovery an important technical means to solve energy shortages. As an important part of campus service facilities, university baths have the characteristics of large residual heat, dense population and high energy consumption. Through field research on several college baths, we can grasp the general energy loss of existing college baths. Starting from the analysis of bathing wastewater, exhaust gas emission and energy loss in the discharge path, combined with sewage source heat exchanger, dual-source heat pump and phase-change water tank, the research on the design of a waste heat recovery system suitable for university baths in severe cold areas is carried out. Using fluent software the system’s total residual heat, water temperature, flow and other parameters in the system are mastered, and finally the formula to derive the system energy utilization is used. The sewage source heat pump, the wastewater–exhaust gas dual-source heat pump and the phase-change water tank are coupled with each other to carry out step recovery of the waste heat of the bath, which provides a new idea for the utilization of waste heat of the auxiliary service of the public institution.

Yuhang Lu, Huixing Li, Guohui Feng, Ang Xu, Weixuan He
Research Status of Composite Applications Based on Phase-Change Energy Storage Technology and Solar Energy

As a consequence of the rapid development of China’s economy and society, its energy requirement has also rapidly increased. Energy shortages and associated environmental pollution problems are placing significant constraints on the sustainable development of China’s economy and society [1]. Solar radiation intensity varies greatly according to geographical location, diurnal cycle, weather conditions, and season. While considering the direct use of solar energy for collection, it is also important to consider the use of certain technical methods for storing the energy in solar radiation—for use when solar radiation intensity is low. Heat storage technology can compensate for the uneven supply of solar energy, thereby maximizing the use of solar energy for buildings. In this chapter, through the application of several phase-change energy storage technologies and solar energy technology, the following conclusions are drawn: solar phase-change energy storage technology not only makes up for intermittent and unstable solar energy, but also helps meet the demand for energy. Such technology can improve the utilization efficiency of solar collectors, reduce indoor temperature fluctuations, and improve comfort in buildings by regulating temperature. Therefore, phase-change energy storage technology has great potential for applications in the field of solar energy.

Shimeng Wang, Huixing Li, Guohui Feng, Xiangyu Lu, Kailiang Huang
Study and Analysis of Storage and Release Capacity of Baffled Phase Change Energy Storage Tanks

According to the characteristics of phase change energy storage and phase change energy storage material selection Paraffin 46#, a baffle-type phase change energy storage tank is designed, and the construction of a model test stand is completed. The main research direction is the heat storage and heat dissipation of the storage tank of the energy storage tank, and the statistical analysis of the test data. The results show that the optimal number of phase change thermal storage units is about 20% of the total volume of the phase change thermal storage unit. In this state, the storage and heat release capacity of the phase change thermal storage tanks are increased by 53% and about 55%, respectively.

Xingyu Diao, Huixing Li, Guohui Feng, Kailiang Huang, Hao Sun
Introduction to the MARKAL Energy Modeling Method for Regional Public Institution Energy Planning—The Liaoning Area

This chapter introduces the special research completed as part of the “13th Five-Year Plan” national key R&D project entitled “Research on Coordination Coupling Technology and Evaluation Index of Passive Energy and Active Energy Optimization in Public Institutions”—a study of the coordination and coupling model for active and passive energy optimization in public institutions. This chapter demonstrates the application of the energy supply and demand linear programming MARKAL model for use in regional public institution energy planning. Based on investigation and research into the existing MARKAL energy planning model, Liaoning Province was used as a test case for exploring the MARKAL model for use in public institution energy planning—one specific application was the provision of technical support for the realization of the “13th Five-Year Plan” in terms of active and passive energy coupling.

Shui Yu, Qixiang Gao, Jianghui Yang, Guohui Feng
Performance Analysis and Comparison of a Combined Solar Chimney

There has been substantial research undertaken on the role of solar chimney, which can reduce energy consumption and improve the indoor environment dramatically. A combined solar chimney structure composed with inclined roof solar chimney and Trombe wall was proposed and simulated numerically, which can be utilized to enhance natural ventilation effectively with better thermal efficiency. In this study, the performance of the air flow in solar chimney was simulated and validated. On the basis of simulation, the performance of the proposed combined solar chimney was compared with inclined roof solar chimney and typical Trombe wall with the similar size. Compared with inclined roof solar chimney and Trombe wall, the air flow rate of combined structure can be increased up to 33% and 55%, respectively. The results of this study support the view that the combined solar chimney can not only improve the ventilation performance in summer but also passively cool the room.

Xiaohang Yuan, Huifang Liu, Jinxiang Liu, Chen Jin, Xiaolei Yuan
Battery Capacity Reduction for Stand-Alone PV Air Conditioner by Using Curtailed Electricity to Store Chilled Water as a Backup

Due to good matching between solar irradiation and cooling demand both in time and quantity, trying to make PV air conditioner independent from public grid so as to develop a stand-alone PV air conditioner is always a struggling objective for researchers and engineers. However, limited by the high cost of battery, it is a hard task to popularize stand-alone PV air conditioner among broader areas. In this paper, a strategy, which converts curtailed electricity of PV system into cooling storage as a backup for cooling demand, to reduce battery capacity for stand-alone PV air conditioner is proposed. To investigate the effect of this strategy, a stand-alone PV air conditioner with both battery and chilled water tank is built in TRNSYS. A fictive office building in Haikou is chosen to do case study. Through sizing work, the results show a reduction for battery capacity, which supports the application of this strategy.

Liang Hu, Yanfeng Liu, Dengjia Wang, Jiaping Liu
Data Association Mining for Identifying Cooling Energy Waste Patterns and Corresponding Improving Suggestion

Due to the great mismatch between the number of occupants and the cooling capacity of air-conditioning system at non-working time in office building, space cooling during non-working time (night cooling) causes enormous waste. In order to identify and reduce cooling energy waste patterns during non-working time, this paper provides a method based on data association mining. As an application for the provided method, an HVAC system, which utilizes river water-source heat pump and water thermal storage technology, in an office building was on-site measured. According to the on-site measure, it could be found that cooling capacity for non-working time is much higher than that was required. Moreover, it was calculated that average COP of river water-source heat pumps rose to 6.7 from 6.3 by eliminating night cooling. The result indicates that reducing the energy used for night cooling is important for energy saving. On the basis, several suggestions for improving energy consumption are proposed for operation.

Yucong Xue, Yang Geng, Jiajie Hong, Kang Zhao, Yidong Qian
Simulation Research on Indoor Environment and Energy Consumption of Multiple Radiant Heating Modes

This study aims to compare characteristics of indoor environment and energy consumption of multiple radiant heating modes as well as their combination in winter. A simulation software, EnergyPlus, was used in this study. An office room model based on a real room which was located in Changsha, China, was established. Several radiant heating models with different radiant surfaces and their combinations were selected for simulation. Besides, two conventional heating modes were selected as comparisons, i.e. split air conditioning system and fan coil + fresh air system. In order to compare energy consumption of different systems under a similar condition, PMV = 0 was set as the indoor set-point of all heating systems in this study. A detailed analysis on all heating systems was conducted on the winter heating design day. The obtained results indicated that the system of radiant ceilings, side walls and floor is the best combination. This study provides references of selecting different radiant heating modes for thermal comfort and energy efficiency in winter.

Chenyu Huang, Nianping Li, A. Yongga, Lizhi Huang, Chenzhang Yuan, Yongsi Wang
Analysis on the Influencing Factors of Typical Residential District Model in South China’s Pearl River Delta

With the developing concentration of urban population in the Pearl River Delta (PRD), the research on both commercial and residential building performance simulation is attracting increasing attention. In this paper, the plane and elevation parameters (such as building size, distance, shape, shape coefficient, storey height, window-to-wall ratio, etc.) of about 100 residential districts in the PRD since 2010 were statistically analysed, which lay a solid foundation for the definition of a typical residential district model. The model of typical residential district can be used to evaluate the energy-saving effect and potential of various technologies, which is of great significance to the technology research, policy formulation and market orientation.

Huiwang Peng, Meixiang Li, Manning He, Zhimin Zheng, Yu Huang, Lang Wu, Haokai Xu
Fitting Analysis for Flow Coefficient Predictive Model of Residential Buildings with High Airtightness

The flow coefficient is an important parameter of air infiltration, affected by many factors, such as building parameters, wind speed and temperature difference between indoor and outdoor. And its modeling is used to adopt the method, multiple linear regression, ignoring the problem caused by characteristic of small sample size. Stepwise regression, least squares and partial least squares (PLSs) with corresponding independent variable screening methods are adopted to obtain the predictive models which are compared with F-test, goodness of fit and CV (RMSE). The result shows that the goodness of fit of apartment’s model and villa’s model received by PLS is increased by 25.9% and 2.2%, respectively, compared with least squares and the PLS models’ CV (RMSE) which are 9.4% and 18.3%. Considering the essential characteristics and fitting results of the three methods, it can be concluded that PLS which is suitable for small sample size is the preferred choice for the establishment of flow coefficient model.

Wenqian Zhou, Xiangli Li, Lin Duanmu
System Structure and Operation Analysis of University Energy Conservation Supervision Platform

Through the real-time monitoring of key cities and buildings across the country, energy consumption statistics, energy consumption auditing, energy efficiency publicity and energy consumption analysis were adopted to realize the management mechanism of energy conservation operation of national large public buildings. However, the operational analysis methods of the energy conservation monitoring platform and its guiding significance for the energy conservation renovation project have not appeared after construction. This study aims at summarizing the problems existing in the operation and use of the energy conservation monitoring platform and proposing the guiding significance of monitoring data analysis for energy conservation reform. This paper introduces the system architecture and main functions of the energy conservation supervision platform of a university in Shenyang. Based on the measured results in operation, the energy consumption data of the campus is statistically analyzed and compared, and the application effect of the energy conservation monitoring platform is analyzed in combination with the energy conservation renovation project.

Na He, Guohui Feng, Cheng Wang, Lin Wang
Meteorological Classification of Water Source Heat Pump-Assisted Solar Water Heating System Based on Cluster Analysis in Winter of Northern Region

The method of classification in meteorological parameters is adopted to optimize the operation mode of water source heat pump-assisted solar water heating system under different meteorological parameters in winter of northern region. We select solar radiation as the first-level indictor; the daily solar radiation is divided into four periods as four secondary indictors of solar radiation. The 60-day weather data of winter in Shenyang are in clustering analysis by using clustering method. The results are confirmed by Bayesian discriminant analysis. Furthermore, the operation mode is analyzed on the platform of TRNSYS under the selected typical day of each group. The 60 meteorological days are divided into seven groups based on the results of cluster meteorological analysis. The distribution law of the hourly solar radiation is similar among each group. Consistent rate of discriminant and clustering analysis results is higher than 96.6%. In addition, the optimal heat pump operating time of each group is determined by the minimum energy consumption which is treated as the optimization objective.

Guohui Feng, Huanyu Li, Xulin Li, Chuan Tian, Mengyuan Liu
Study on Appropriate Partition of Shallow Geothermal Energy and Active Energy Coupling Utilization

In recent years, with the development of shallow geothermal energy, problems such as waste of groundwater resources and low energy saving efficiency have gradually emerged. Therefore, it is necessary to partition the utilization of shallow geothermal energy appropriately. In order to solve the problem that the evaluation indexes of the suitable partition of coupling utilization of shallow geothermal energy and active energy are multi-level, multi-objective and difficult to quantify, this paper discusses the feasibility of evaluating the suitability partition by using the combination method of analytic hierarchy process and entropy weight method. This method ensures the rationality and accuracy of weight assignment. Based on this method, the suitable partition model of shallow geothermal energy and active energy coupling utilization in Shenyang area is established. It can be concluded that this method has a certain extension value and can provide the basis and support for scientific zoning and rational development of the suitability of coupling utilization of shallow geothermal energy with active energy.

Guohui Feng, Mengyuan Liu, Xulin Li, Chuan Tian, Huanyu Li
Simulation of Summer Energy Consumption of a Low-Energy Building in Severe Cold Regions and Comparative Analysis of Measured Data

Energy consumption simulation calculation for ultra-low-energy buildings and comparative analysis with actual operational data. It can provide reference for the rationality of ultra-low-energy building energy simulation application and the feasibility of operation management and simulation optimization operation strategy. Take the Sino-German Energy Conservation Demonstration Center of Shenyang Jianzhu University as an example. Simulation of building load is done by using building energy simulation software DeST-c. Select a few days with little difference in outdoor temperature for comparison and compare the simulation results with the measured energy consumption results. DeST-c’s simulated cumulative cooling load is 998.26, 1099.54, and 838.13 kWh. The measured load is 1233.94, 1220.35, and 1020.46 kWh and is combined with the actual analysis of the reasons for the difference. Through the comparison between simulated and actual measurement, the actual load is larger than the simulated load. The maximum deviation between the simulated load and the measured load is about 19%, indicating that the construction process is poor during the construction phase, making the actual load larger. At the same time, it also provides reference for the rationality of DeST-c software for the simulation application of low-energy building energy consumption in severe cold regions.

Guohui Feng, Jiaji Zhao, Kailiang Huang, Xiaolong Xu, Chuan Tian
Research on the Application of Multiple Forms of Renewable Energy Integrated Coupled Heating System in Rural Buildings

Rural buildings generally suffer from poor thermal insulation performance, large body shape coefficient and high energy consumption in heating systems. They not only consume a lot of fossil energy, but also cause serious environmental pollution. Therefore, in the field of building heating, especially in rural areas, it is necessary to promote the application of renewable energy. A single form of energy system has shortcomings such as instability and low efficiency; this article grasps the research process of renewable energy complementary systems applied in the field of architecture and industry and analyzes its application feasibility and prospects in rural buildings.

Guohui Feng, Jiasen Liu, Xulin Li, Hua Li
Research on the Air Infiltration under Thermal Pressure in Megatall Buildings

The rapid growth of population has promoted the construction of the megatall buildings taller than 600 m whose height might bring new issues to the building energy saving. To investigate the effect of the building height on the distribution of thermal pressure in megatall buildings, we simulated the thermal pressure distribution and air infiltration using the multi-zone network model CONTAMNv3.2. The building models were set up considering the typical conditions with height interval of 200 m ranging from 600 to 1000 m, and the outdoor meteorological parameters were set up based on the temperature ranges according to the cold region and the sever cold region in China. It is revealed that the thermal pressure increases with the increase in the building height, together with the decrease in the outdoor temperature. Besides, the energy consumptions from the air infiltrations were calculated based on the same conditions, among which the variation of air density was considered. The findings can be exploited to reduce the energy consumption of air infiltration in the megatall buildings.

Junwei Xue, Junliang Cao, Xiaoxin Man, Zhitao Han, Jing Liu
Test and Analysis of Summer Energy and Thermal Environment for the Nearly Zero-Energy Building in Severe Cold Area

Nearly zero-energy buildings (nZEBs) have transitioned from examination success to demonstration with broad prospects of development in the future. The actual operational effects of the building were evaluated through thermal environment testing and subentry energy consumption statistics. In August 2018, the energy consumption of the nearly zero-energy demonstration building of Shenyang Jianzhu University was measured. Based on data analysis, the daily electricity consumption is about 52.4 kWh, of which the energy consumption of the heat pump unit accounts for about 18% while that of water pump is about 55%. Besides, the fresh air ventilator consumes about 5%, and the fan coil is about 21%. Lighting takes up about 1% at last. The results show that the air-conditioning system runs well in summer. Besides, the temperature is stable between 23 and 25 °C, and indoor temperature in air-conditioning system is turned off 24 h can still steady at 24.73 °C, the building has good cooling keeping properties.

Guohui Feng, Yue Wang, Xiaolong Xu, Kairan Wang
Analysis on the Task-Ambient Micro-environment and Thermal Comfort of a Workstation with Local Radiant Panels and Local Airflow

In this paper, the background temperature and manikin thermal sensation obtained by the experiment and simulation under three conditions were compared. The boundary conditions required by CFD simulation were set with the experimental data, and the model was adjusted to verify the accuracy of the simulation. The simulation results showed that both local radiant panels and desk fan could effectively reduce the mean skin temperature (MST) and thermal sensation of manikin. In addition, when both facilities were turned on, the manikin’s MST dropped further. Two kinds of facilities were optimized, respectively, and the respective parameters were obtained when the MST of manikin dropped to the thermal neutral level. In order to avoid the problem of condensation and draft risk, the two kinds of facilities were optimized at the same time, and the respective parameters were obtained when the MST of manikin dropped to the thermal neutral level, and the problems of condensation and draft risk were also avoided.

Chenzhang Yuan, Nianping Li, A. Yongga, Chunhui Song, Chenyu Huang, Yongsi Wang
Test and Analysis of Airtightness of External Windows for the Nearly Zero-Energy Building in Severe Cold Area

Doors and windows are the key components that affect the energy-saving effect of nearly zero-energy buildings (nZEBs). Airtightness energy use in buildings accounts for around 50% of the building energy consumption. Therefore, the energy efficiency performance of doors and windows is the key to achieving energy-saving indexes for nZEBs. In this paper, the airtightness of the external window of the nearly zero-energy demonstration building of Shenyang Jianzhu University is carried out. Through the testing and analysis, the air permeability performance of the external window of the demonstration building reaches 8 levels. Simultaneous testing combined with infrared thermal imaging method, qualitative analysis of the weak part of the external window airtightness is the gap between the window frame and the wall. The test results of this study can provide data support for the study of the airtightness of the external windows of nZEB in severe cold area.

Guohui Feng, Yue Wang, Xiaolong Xu, Kairan Wang
Influence of the Shade from Other Occupants on the Angle Factor between a Human Body and Radiant Surface in Buildings

In a real room with radiant surfaces for heating or cooling occupants, the radiant heat transfer between a certain human body and radiant surfaces is largely affected by other indoor objects such as other occupants. Nonetheless, this point is usually ignored in current studies. This study aims to quantify the influence of the shade from other indoor objects on the angle factor between a human body and radiant surfaces. First, a simplified 3-D model of standing human body was established on the basis of the Chinese adult human body size. ANSYS Fluent was used for calculating angle factor values between a human body and radiant surface in a room with a size of 5 m × 5 m × 5 m (length × width × height). The concept of relative angle factors was proposed and a first-order exponential correlation was found between the position and the relative angle factor. In the non-shaded condition, as the human body had larger horizontal distances or smaller vertical distances, the decrease in both angle factors and relative angle factors became faster. In the shaded condition, the angle factors decreased when the horizontal position of the shade human body closed to the center line of the radiant surface or the vertical position of the shade closed to the edge of the radiant solid angle.

Yongsi Wang, Nianping Li, Jian Hu, Yingdong He, A. Yongga, Chenzhang Yuan, Meng Wang
EnergyPlus and Python Co-simulation Model to Support Machine Learning-Based Control of Ground-Source Heat Pump System

As the world pays more and more attention to energy conservation and environmental protection, the ground-source heat pump system has been rapidly popularized in China. The machine learning-based automatic control technology can help to improve the energy efficiency of the ground-source heat pump system. However, the quality of the measured data is often not clean enough to train the machine learning algorithms. On the other hand, building energy simulation can generate clean data to support machine learning-based control techniques. This study presents a framework to generate EnergyPlus Functional Mockup Units (FMUs) for co-simulating with Python environment. A case study was presented to create an EnergyPlus FMU of an office building with a ground-source heat pump system in Beijing. The basic EnergyPlus model was generated using the Commercial Building Energy Saver developed by Lawrence Berkeley National Laboratory and modified to include the ground-source heat pump system. The model was calibrated using the measured sub-metering data to meet the ASHRAE 14 requirement. To support the machine learning technique, an EnergyPlus FMU was developed to co-simulate with Python environment. EnergyPlus outputs the current room and system status parameters to Python and obtains the control signals from Python. In the future, we will work with machine learning experts to train and evaluate their control algorithms using the developed co-simulation platform.

Chuhao Yang, Yixing Chen, Nianping Li, Yifu Sun, Ruosa Wu
An Investigation on the Dynamic Response Property in an Underground Tunnel Space with Constant Temperature

The cutting-edge scientific research calls for the emergence of some special high-precision thermostatic chambers, which are characteristic of large space and many internal and external disturbances. These chambers mainly function by chilled water taking away most of the heat generated by the internal heat source and adjusting the air supply by air conditioners to ensure the constant temperature accuracy of the laboratory room. In order to improve this, the paper employs the numerical simulation method to study the temperature response characteristics of airflow organization under different air supply modes and the dynamic response characteristics of different air supply temperatures to constant-temperature region. The research finds the optimal airflow distribution pattern and the location of the optimal control point, which provides the reliable foundation for the high-precision control solutions for underground constant-temperature space. The research results show that the air distribution under the lower air supply mode is more resistant to interference than that under the side air supply. The delay time coefficient and system time constant of the control point located in the middle of the constant-temperature zone and equal to the design temperature are smaller than the conventional control point of the air outlet central. Therefore, the control point equal to the design temperature can make the system react faster and the sensitivity is higher, which will help to make the high-precision control of the constant-temperature space.

Chao Wu, Xu Zhang, Jingtao Huo, Wenxuan Zhao, Wei Ye
Influence of Window-to-Wall Ratio on Calculation Methods for Building Surface Reflectivity

Solar radiation is the main source of building heat gains. Radiative heat transfer on building surface is not only the thermal environment analysis foundation, but also the primary task of calculating building heat gains. Reflectivity is an important calculation parameter for the radiative heat transfer process. In this paper, different building models are established by three building surface reflectivity calculation methods according to window-to-wall ratios. The building surface temperatures are compared, and the reflectivity-sensitive interval can be obtained. The results show that the influence of window-to-wall ratio, wall reflectivity, and seasons on three methods is obvious. When the wall reflectivity is small, the calculation methods are not influenced by four seasons. When the window-to-wall ratio is less than 0.5, the reflectivity-sensitive interval is [0.5, 0.9], and on other intervals, it is [0.1, 0.9]. Therefore, in order to make the radiative heat transfer simplified calculation more reasonable, different calculation methods could be selected according to the actual window-to-wall ratio. The research results provide a theoretical basis for the outdoor thermal environment analysis.

Zhengrong Li, Heyu Wang, Qun Zhao
Numerical Investigation on Energy Efficiency of a Serial Pipe-Embedded Window System Operated in Summer Considering Water Temperature Change in Pipeline

Pipe-embedded window with low-grade energy can significantly reduce the cooling load of buildings. However, previous studies are generally based on the same water temperature for all the pipes, which is equivalent to parallel pipe-embedded window (PPW) and results in a very small temperature difference between inlet and outlet of pipes. A numerical model of serial pipe-embedded window (SPW) is developed, and the load reduction potential and performance of the SPW considering water distribution are studied in this paper. The results show that: (1) the SPW still has a satisfactory load reduction effect which is slightly less than that with the PPW; (2) the COP of the SPW system is far higher than that of the PPW system after considering water distribution; (3) the water temperature affects the indoor load more than the outdoor air temperature, and natural sources with temperature below 38 °C can be utilized effectively by a SPW for energy saving.

Sihang Jiang, Xianting Li
An Evaluation Model for Indoor Light Environment

Indoor luminous quality affects occupants’ health a lot, but no mature solution exists to assess the quality. The objective of this paper was to develop a practical fuzzy evaluation model for light environment. Based on previous studies and a series of luminous experiments, illuminance, correlated color temperature and illuminance uniformity were chosen as evaluation indicators and a fuzzy synthetical evaluation model with five grades was developed.

Jingyun Shen, Zhiwei Lian
Thermoelectric Performance of Micro-heat Tube Array Solar PV/T System Based on Parallel Flow Tube with Tiny Porous Channels

This paper presents a solar photovoltaic–thermal cogeneration component based on parallel flow tube with tiny porous channels and micro-heat tube array (MHPA-PV/T). The core heat transfer component effectively combines micro-heat tube array and parallel flow tube with tiny porous channels and applies to solar photovoltaic/thermal system. The heat collection efficiency and power generation efficiency of the two systems under instantaneous and all-day operation conditions are studied and analyzed, respectively. The results show that the instantaneous heat collecting efficiency of the tiny channel flow tube with the MHPA-PV/T components’ maximum value is 36.8% and increases by 14.6% and the photovoltaic increases by 5.5%. The daily average photovoltaic conversion efficiency improves by 9.8% in the all-day efficiency test system, and the daily average photo-thermal conversion efficiency enhances up to 11.1%, compared to the component of airfoil tube in the testing system. The MHPA-PV/T components based on parallel flow tube with tiny porous channels provide a theoretical basis for the practical application and popularization of the solar cogeneration technology in the future.

Heran Jing, Zhenhua Quan, Yaohua Zhao, Ruixue Dong, Ruyang Ren, Zichu Liu
Research of Building Heat Inertia Cycle Based on Data Mining

In this paper, a periodic regression prediction model of building thermal inertia was established, based on the time series historical data of the actual monitoring of intelligent heating system, which took outdoor temperature, indoor temperature and historical heat consumption as independent variables. MATLAB software was used to conduct regression prediction analysis on the heat consumption of radiator heating buildings with different thermal performance. Through analysis, it was also found that the heat consumption was affected by the thermal inertia period of buildings, and then, the concept of thermal inertia period of buildings was put forward. Through the analysis of the relative error of regression results, it was found that the cycle of building thermal inertia went through three periods, namely fluctuation period, stationary period and fluctuation divergence period. Buildings with different thermal properties usually have different optimal thermal inertia cycles, and with the improvement of thermal performance, the optimal thermal inertia cycle becomes longer. The study of building thermal inertia period provides valuable theoretical reference for the accurate prediction of heating parameters in heating system.

Chunhua Sun, Jia Zhu, Fengyun Jin, Jiali Chen, Haoyu Feng
Experimental Investigation of Dust Particle Deposition Reduction in Solar Cell Covering Glass by Super-Hydrophobic Coatings

Airborne dust deposition on energy devices would cause serious efficiency and lifetime reduction, such as solar photovoltaic panels. Mechanical or manual cleaning using water is commonly expensive and frequent. Recently, super-hydrophobic coating becomes a new promising way to mitigate the dust deposition issue on PV panels. However, the property of super-hydrophobic coating on preventing dust deposition on PV panels with different tilt angles has been seldom investigated and remains unclear. Thus, this paper investigated dust deposition reduction in PV panels with and without self-cleaning coating by experimental measurement. The effects of different tilt angles of PV panels and micro–nano-structures of self-cleaning coating on dust deposition behaviors were studied in details. It was found that super-hydrophobic coating can greatly reduce dust deposition density on the solar cell covering glass. The dust deposition density on the surface with super-hydrophobic coating is just 44.4%, 28.6% or 11.2% of the surface without super-hydrophobic coating for tilt angle θ = 30°, θ = 45° or 60°, respectively. The coating with micro–nano-structures can obviously improve the anti-dust ability by 15.3% compared with the coating without micro–nano-structures. The coated glass has obviously higher spectral transmittance and PV efficiency after dust deposition compared to the bare glass case. Therefore, the conclusion can be expressed as super-hydrophobic coating with micro–nano-structures can be an effective way to mitigate the dust deposition on solar PV panels.

Anjian Pan, Hao Lu, Lizhi Zhang
Research Status of Building Energy Consumption Analysis Based on BIM Technology

Energy consumption simulation analysis is one important way to evaluate and optimize building energy conservation measures. As an innovative tool and production mode, BIM provides a new approach for building energy consumption simulation analysis. The BIM technology is used to simulate the building energy consumption and compare it with the traditional energy consumption analysis method. The main differences are the energy consumption analysis participants, software, analysis process, and energy analysis data. Summarize how BIM technology can be applied to building energy-saving analysis of building projects, so that architects can correctly understand the feasibility and applicability of BIM software in building energy-saving, and promote BIM technology. Research on energy consumption simulation Analysis method for specific buildings by using Ecotect Analysis software in BIM technology, and analyze the advantages of Ecotect Analysis in building energy consumption Analysis and architectural design guidance. Therefore, BIM technology plays an important role in building energy conservation optimization.

Heling Ma, Huixing Li, Guohui Feng, RuiYang Gao, Kailiang Huang, Xinwei Wang
Energy Performance of a Building-Integrated Photovoltaic/Thermal System for Rural Residential Buildings in Cold Regions of China

Building-integrated photovoltaic (BIPV) technology provides an aesthetical, economic, and technical solution for electricity self-sufficiency in buildings. This paper proposes a novel triple-skin BIPV/T system for rural residential buildings in north China. Firstly, the electrical performance of the proposed system was simulated using the System Advisor Model (SAM) from National Renewable Energy Laboratory (NREL). Secondly, the ANSYS Fluent software was used to simulate the heat transfer condition of the BIPV/T system in a typical winter day. The results show that the total electricity output of BIPV/T system in a typical year is 6128 kWh. In a typical winter day, the proposed system operates from 8:00 to 13:00 and outputs 9.84 kWh electricity in total. By collecting the accumulated heat from the PV module, the exposure temperature of the structural wall/roof is significantly improved. Accordingly, during the operation of the system, the total heat loss of the building envelope could be reduced by 2.85 and 2.75 kWh by the closed mode and the ventilated mode, respectively.

Tiantian Zhang, Meng Wang, Hongxing Yang
A Multi-criterion Optimization for Passive Building Integrated with Vacuum Photovoltaic Insulated Glass Unit

This article optimizes building design parameters to balance the building energy-saving and visual comfort objectives when utilizing the vacuum photovoltaic insulated glass unit (VPV IGU) as the building envelope. VPV IGU can reduce the air conditioning load as demonstrated in a previous study, where the window-to-wall ratio should be decreased to approximately 10% for energy saving. However, under such circumstance, the indoor visual comfort for the occupants cannot be guaranteed. With a simultaneous consideration of both the visual comfort and energy efficiency, this work explores the optimal passive building design through a multi-criterion approach based on the non-dominated sorting genetic algorithm II (NSGA-II). The annual energy and indoor environmental conditions of the selected prototype office building are predicted with EnergyPlus. Obtained results are then subject to a decision-making process to determine the final optimum solution which can provide guidance in green building design within different urban contexts.

Junchao Huang, Xi Chen, Hongxing Yang
The Effect of Adjacent Room Heat Transfer on Household Heat Metering

Household heat metering has become an inevitable trend in the reform of heating in northern China, and it aims to realize energy saving from users’ behavior while ensuring the indoor thermal comfort. Due to the different building envelopes, occupants’ preference and occupancy rate of each house, the heat transfer from adjacent room will greatly affect the fair share of the household’s heating fee. This study adopts EnergyPlus for building modeling and heating load calculation. A total of 17 rooms in one building are measured with temperature in both indoor and outdoor from Jan 22 to Feb 5, 2018. Building model is established according to the real building plan and envelope materials, and the time-dependent temperature of the simulated room is compared with the minutely measured temperature to validate the model accuracy. With the valid model, the actual ratios of heat transfer go to/from adjacent room to the heating load are calculated. The results indicate that the heat transfer to adjacent rooms in one day accounts for near 70% of the total heating load, which will provide basic data for fair heating charging and be conducive to the implementation of household heat metering in China.

Fan Yang, Peng Xue, Mengjing Zhao, Ye Zhang, Jiaping Liu
A Study of 9 Existing Municipal Organs in Shanghai: Analysis of Building Energy Consumption Characteristics, and Energy-Saving Suggestions for Operational Problems of Main Energy Consumption Systems

With the development of government social services and the growing scale of various municipal organs such as medical, exhibition and education, the energy consumption of existing municipal organs has become an important component of building energy consumption of China. However, there are relatively few studies on the energy consumption and operational problems of existing municipal organs. The purpose of this paper is to provide support and reference for related research. Based on the existing nine municipal organs in Shanghai, this paper analyzes the energy consumption characteristics, the main energy system operation effects and the main energy system operation problems by means of on-site investigation, system measurement and data analysis. Finally, energy-saving recommendations and energy-saving estimates are given.

Guangwei Deng, Weifeng Zhu, Qingpeng Wei, Qian Ye
Prediction and Factors Determination of District Heating Load Based on Random Forest Algorithm

High energy consumption of district heating system can be improved by control strategy. Accurate prediction of heat load is very important for optimizing system control. Selecting reasonable input parameters is also the key to accurate prediction. Therefore, this paper establishes a short-term heat load forecasting model based on random forest regression (RFR), forecasts the heating load of a district in Xi’an, analyzes the most influential parameters in different month, and compares the forecasting results with the support vector regression (SVR). The results show that the performance of RFR model is better than that of SVR model by 10.2%. The load factors in different heating stages are not identical, indicating that energy operation mode has changed. Therefore, in different heating periods, the change of influencing parameters can be considered appropriately, and the prediction model can be adjusted to help the reasonable operation of the heating system and improve the energy efficiency.

Xiaoxue Hu, Yanfeng Liu, Yong Zhou, Dengjia Wang
A Simplified Dynamic Model of Roof Integrated with Shape-Stabilized Phase Change Material

Roof integrated with shape-stabilized phase change material (SSPCM) is composed of the PCM layer and the precast concrete hollow slab, the PCM layer is placed on the outer layer of which. During daytime in summer, the PCM absorbs and stores the solar radiation heat and releases the heat by convection and long-wave radiation at night. This can effectively reduce roof heat transfer and inner surface peak temperature. In order to study the thermal performance of the structure, a simplified dynamic thermal network model (RC model) of the roof is established. The resistances and capacitances of the PCM layer and hollow slab layer are identified by using genetic algorithm (GA). Firstly, the parameter identification of the hollow slab layer’s RC model can be obtained by matching the frequency response characteristics of the simplified model with its frequency-domain finite difference model. Another GA program is then used to find out the optimal resistances and capacitances of the PCM layer’s RC model (together with the parameters identified of the hollow slab layer) which gives the best fitting with the heat performance by using CFD numerical simulation in time domain. Further, the thermal performance of the roof integrated with shape-stabilized was investigated under a typical summer day in Wuhan. The simulation results showed that the use of PCM has helped to increase the thermal insulation of the roof, compared with the roof without PCM layer, the decrement factor is decreased by 0.31, and peak internal surface temperature is decreased by 7.02 °C when the PCM is 30 mm.

Qingchen Yang, Jinghua Yu, Junchao Huang, Shan Peng, Junwei Tao
Influence of Inlet Turbulent Characteristics on CFD Predictions of Indoor Flow Field and Ventilation Performance

The turbulent characteristics of the inlet of a ventilation system have great influence on the airflow characteristics and indoor pollutant distribution. However, the significance of inlet turbulence has not been sufficiently addressed. In order to understand such influence, this paper uses the standard k-ε model to simulate the airflow characteristics and indoor pollutant distribution of IEA20 benchmark test. The values of inlet turbulence intensity were changed from 4 to 20%. The simulation results are compared with the experimental data in the literature. At X = h/2, the difference between simulated values and experimental data increases with increasing turbulence intensity. At X = H − h/2, with the increase in air supply distance, the simulation value and the experimental data eventually show a certain error. The experimental data near the wall are negative, and the simulated values are positive. The effects of different turbulence length scales on the velocity field are also studied. This is further extended when considering the presence of indoor pollution sources.

Qiong Guo, Xiangzhe Meng, Haidong Wang
Numerical Study on Thermal Efficiency of Large-Scale Flat-Plate Solar Collectors

The flat-plate solar collectors have better efficiency characteristics in low-temperature region. With the development of solar thermal utilization technology, the research of collectors suitable for different temperature requirements, application sites and personalized design of collectors will be a new direction in the future, and the flat-plate solar collectors used in solar heating system will be a development trend. Therefore, it is proposed that the flat-plate solar collectors should increase their collector efficiency and outlet temperature by increasing the scale. According to the heat transfer mathematical model of flat-plate solar collector, the relationship between heat-collecting area and collector efficiency was studied. In this paper, the 3-D physical models of the large-scale flat-plate solar collectors were established. The CFD software was used to simulate the operation characteristics of large-scale flat-plate solar collectors under different working conditions, and the heat loss, heat collection and thermal efficiency of different scale collectors were analyzed. It is shown that the instantaneous efficiency of large-scale collector is 1– 4% higher than that of parallel collector.

Dengjia Wang, Yuchao Ren, Yingya Chen, Yanfeng Liu
Luminous Environment Measurement and Simulation Analysis of a University Library

The self-study area is a typical and mostly-used space in the library, therefore the light environment in this room directly affects students’ learning efficiency and physical health. Field measurements and questionnaire surveys were conducted on the light environment. The results showed that the average illuminance of the artificial light environment could not meet the standard, while the average illuminance of the natural daylighting and mixed light environment far exceeded the standard, but the uniformity was poor. Aiming at the above problems, ECOTECT and DIALux were, respectively, used to study the effect of different shading forms and indoor light environment under different shading and lighting schemes. The results confirmed that among the three shading methods of the horizontal device, vertical device, and sun-shading blind, the effect of sun-shading blind shading is the best, and the environmental quality is optimal with the uniform arrangement of LED lamps. In addition, control recommendations combining natural daylighting with artificial lighting are proposed.

Guodan Liu, Xiaowei Chen, Yubin Zhang, Zhixin Wang, Run Teng, Chuanrui Li
Thermal Model for Building External Wall under Low Atmospheric Pressure and High Solar Radiation Conditions in Plateau Area

Conventional building heat transfer modelling approach is mainly for low-altitude places, which neglect the unique climatic features in plateau areas. The improved building thermal model of external wall in plateau area is established, with the consideration of low atmospheric pressure and high solar and long-wave radiations. The impact of low air density on heat convection coefficient is analysed. Hence, the correction factor is proposed to assess the radiation influence on building external walls. According to the theoretical modelling and analysis, the coefficients of convection drop by 25% and 33% for inside and outside wall surfaces, respectively, when the altitude rises from 0 m to 4500 m. Moreover, the equivalent temperature has close relationship with the wall-facing direction, as well as the absorption ratio of solar radiation. Heat transfer correction factor always declines with growing solar heat gains. The present study can provide guidance and reference for the design optimisation of plateau buildings.

Yin Zhang, Enshen Long, Jin Li, Fei Gao
Investigation on Energy-Saving Walls of Houses in Rural Hangzhou

In this paper, for Hangzhou rural residential buildings with the three energy-saving walls, the external or internal insulation wall and green wall, the hourly heat gain and cooling/heating load were simulated by DesignBuilder. Then, the heat transfer performances of the three energy-saving walls in continuous and intermittent air conditioning mode were compared. The results show that the effects of the orientations of the three energy-saving walls have similar characteristics. The reduction rates of the annual cooling loads of the three energy-saving walls to the traditional wall in intermittent air conditioning mode are larger than those in continuous mode, and the indoor operative temperatures and cooling loads of green wall are the least in summer in both air conditioning modes. Moreover, the reduction rate of the annual heating cooling load of the green wall is smaller than that of its annual cooling load; however, it is opposite for the external and internal insulation walls.

Nan Liang, Qiongxiang Kong, Ying Cao, Siyan Liu, Yan Yan
Study on Thermal Performance and Ventilation Strategy of Tubular Ventilation Roof

For residential building in rural areas of China, precast concrete hollow-core slabs are widely used as building roofs. However, due to the poor thermal insulation performance and simple structure of the slab, a large amount of heat is transferred to room through the roof structure when the outdoor temperature is high, causing an increase in the indoor temperature and energy consumption of air conditioner. In order to improve the thermal performance, tubular ventilation roof is introduced by ventilating the cavity of precast concrete hollow-core slab in summer. A two-dimensional frequency-domain finite-difference model (FDFD model) and a simplified dynamic thermal network model (RC model) of the tubular ventilation roof were developed in this paper. The thermal performance under different ventilation speeds and temperature differences was evaluated. The simulation result also showed that the tubular ventilation roof had the optimum thermal performance at a ventilation speed of 4 m/s during a typical summer day in Wuhan. Compared with non-ventilated conditions, the internal surface peak temperature is reduced by 5.34 °C and the internal surface average temperature is reduced by 2.28 °C, greatly improving the thermal insulation performance of the tubular ventilation roof.

Jinghua Yu, Kangxin Leng, Biaobiao Wang
Analysis of China’s Total Building Energy Consumption and Policy Guarantee Proposal Study under the Background of New Urbanization

Based on the analysis of building energy consumption data, this paper estimates the total energy consumption of buildings in China in the future. Around the control target of building energy consumption, we proposed a policy guarantee system from the aspects of laws and regulations, energy-saving supervise assessment system, working mechanism, energy conservation standards, energy conservation technology, and energy price policy.

Jinhan Liang, Wenjie Zhang, Jianwei Zhou, Xiufeng Tian, Ziqiang Huang
Towards Zero Emission Residential Buildings (ZEBs) in a Humid Subtropical Climate. Analysis Emissions from Energy Use and Embodied Emissions from Materials in Referential Locations According to Obligatory Residential Energy Codes and Using Generic LCA Data Sources

The primary objective of this paper is to investigate whether is it possible to achieve a zero greenhouse gas emission residential building (ZEB) operating in a humid subtropical climate. Sydney, Atlanta, Shanghai and New Delhi, recognised as main regional policymaker centres, were included in the scope of analysis as referential locations. Calculations of annual energy consumption, embodied emissions from production (A1-A3) and replacement (B4) of construction materials, as well as on-site renewable energy production, were performed on the basis of mandatory energy standards, building performance simulations and generic, process-based life cycle data. All calculations were based on a single-family building model with timber construction. All building’s thermal energy demands are provided by electrical air-to-water heat pump with a backup from an electric coil heater. Additionally, the roof-mounted photovoltaic system is used specifically to reduce GHG emission from building operation and materials. The preliminary results of this study show that zero emission ambition level for residential building is obtained in Sydney and Atlanta, where mandatory energy codes enforced high standards of building energy performance. The paper presents and discusses the results of the environmental impact for a model residential building in each of the specific humid subtropical climate locations. Additionally, general adjustments of the energy codes requirements that could enable higher ZEB ambitions are proposed.

Daniel Satola, Aoife Houlihan Wiberg, Arild Gustavsen
Building Energy Consumption and Future Energy-Saving Potential Research in China Based on Population Development Model

The construction industry is one of the major energy-saving fields. It is necessary to define the target of energy conservation and emission reduction targets according to the future social and economic development needs and the energy characteristics of the construction industry. Based on the population development model, a top-down method was used to calculate the stock of building floor space in China in this study. A bottom-up model was established to the calculated energy consumption of China’s construction sector. Different scenarios of energy consumption in China’s construction field were constructed. The future total energy consumption of buildings under different scenarios was predicted. The results found that under the situation of ‘slow development of urbanization + strict control of per capita area’, by 2050, the total area of various types of buildings in China will reach 69.78 billion m2. Under the scenario of ‘medium energy conservation and emission reduction’, by 2030, the target of building energy consumption control in China is 102 million tce. In order to achieve the goal of energy saving and emission reduction in China, the national building stock should be restricted within 70 billion m2. This paper aims to provide reference for long-term planning of energy saving and emission reduction in China’s construction field.

Wenjie Zhang, Xiufeng Tian, Jinhan Liang, Shengbing Ma, Ziqiang Huang
Simultaneous Test of Heat and Moisture Transfer in Aerogel Blankets

Thermal insulation is one of the most effective methods to reduce the energy loss through building envelopes because of its low thermal conductivity. However, moisture ingress driven by the pressure gradient across the insulation may lead to a variation of the thermal conductivity, which highly deteriorates the thermal performance of building envelopes and further affects the heating/cooling loads. In this paper, a novel simultaneous test method based on the guarded hot box is proposed to investigate the simultaneous variations of moisture content and effective thermal conductivity of thermal insulation. Two types of aerogel blanket are selected as test specimens. The variations of thermal conductivity versus temperature and moisture are measured and compared. Besides, the variations on the appearance of test samples are also discussed in detail.

Haijin Guo, Shanshan Cai, Xuepeng Wang, Dongxu Fang, Kun Li
Simulation Study on the Spreading of Fire-Induced Smoke in Natural-Ventilated Double-Skin Facade Buildings

Double-skin facade (DSF) is getting more and more popular these days due to its energy-saving potential and aesthetics. This particularity design brings certain difficulties to the fire protection of the building. Especially for natural-ventilated DSFs, the smoke flow between floors and DSF is more complicated depending on ventilation strategies. In order to gain more understanding and to acquire reliable data for future design, a naturally ventilated DSF building, Center of Sustainable Energy Technologies in Ningbo, was studied numerically. Computational fluid dynamic (CFD) analysis was carried out focusing on the characteristics of smoke distribution. Results showed that even though CSET building met the national fire safety requirement, it still failed to prevent fire spreading or ensure evacuation safety of occupancy. Simulations also suggested that opening up the DSF during fire would actually be more effective at preventing fire from spreading as well as ensuring occupancy evacuation.

Jingjing Shao, Siegfried K. Yeboah, Tiesheng Zhu, Yilin Li
Simulation Study on the Effectiveness of Passive Natural-Ventilated Facade Devices for High-Rise Public Buildings

Although natural ventilation can save substantial energy in buildings, it is difficult to apply natural ventilation in high-rise public buildings due to the unexpected high wind speed and large noises on higher floors. To this end, this study investigates the effectiveness of passive natural-ventilated facade devices for high-rise public buildings. Numerical models for a case building with passive natural-ventilated facade devices were developed by using CFD methods. The indoor airflow fields on different floors were simulated by utilizing ANSYS Workbench FLUENT software. The results demonstrated that the passive natural-ventilated devices in the case study can achieve satisfactory air change rate on different floors in high-rise public buildings. Nevertheless, the results also proved that the indoor airflow fields were greatly influenced by the wind speed, wind direction, and the height of floors in buildings. Future studies on different boundary conditions are encouraged in order to identify the optimal operation mode and to improve the performance of the façade devices in public high-rise public buildings.

Yilin Li, Hongwei Tan, Weiguang Su, Jingjing Shao
Application Analysis of Phase Change Heat Storage in a Solar Heating System

In recent years, with the continuous implementation of green economy and energy saving, solar heating system has gradually become one of the focuses of attention, but the intermittent and unstable characteristics of solar energy limit its application. Phase change energy storage materials are suitable for building energy saving, waste heat recycling, and solar heating systems due to their advantages of high heat storage density, high heat resistance, high conductivity, low expansion, and easy control. This paper summarizes the principle and classification of phase change heat storage technology, introduces its application in energy-saving buildings, and emphatically analyzes the application form and system performance of phase change heat storage in solar heating. Finally, the development and application tendency of phase change thermal storage technology in solar heating are put forward.

Yuefen Gao, Chengzhi Wang, Meng Wang
The Influence of Interfacial Thermal Contact Resistance on Cooling Performance of the Large Inertia Wall in Nuclear Power Plant

The cooling performance of the heat sink wall within a limited time is a main factor to ensure the thermal environment of the main control room (MCR) under accident conditions in CAP series nuclear power plant. To analyze the effects of thermal contact resistance (TCR) on the cooling performance, we propose a three-dimensional unsteady heat transfer model, which couples the resistance–capacity (RC) method and finite difference method and is validated by experiments. The results show that compared to the ones that ignored TCR, when the value is 10−4, 10−3 and 10−2 m2 °C W−1, the cooling capacity is reduced by 1%, 1.7% and 4%, respectively. Furthermore, the maximum cooling release rate is reduced by 5.46, 5.93 and 11.42% with the time lag 8 min, 9 min and 21 min, respectively. Therefore, the reliability of the safety performance of the MCR under accident conditions can be overestimated if the TCR is not considered.

Xiaoyan Wu, Xu Zhang
Evaluation of Three Analytical Solar Chimney Models with Field Data

The paper reported the measured airflow rates in a solar chimney installed on a detached test house in Hangzhou. The one-week data showed that in addition to buoyancy flow enforced by the solar radiation, significant airflow was also observed in inverse conditions when the indoor temperature was higher than the outdoor temperature even with no solar radiation. Performance of three analytical models, the single-zone model, stratified model, and plume model, was examined to predict the airflow rate of the solar chimney model. The results showed that the plume model and the modified single-zone model agreed with the measurements reasonably well, while the stratified model failed to predict the airflow in inverse conditions.

Shiyi Hong, Qian Wu, Wenqing Ge, Da Lv, Zhengguang Li, Guoqing He
Study on Indoor Natural Light Environment Optimization of Traditional Residential Buildings in South Sichuan

With the progress of economy, technology, natural conditions and lifestyle, the protection and update of traditional residential buildings should adapt to the requirements of the new era and the changes of residents’ needs. However, the indoor natural lighting of most traditional residential buildings cannot meet the design standard of architectural lighting 300 lx. Building windowing is an important way to get indoor natural lighting, but improper windowing location, windowing area and window form may cause the room to lack privacy, cold air penetration, indoor thermal comfort decline and other problems, thus leading to the decline of indoor environment comfort. Aiming at comfort and energy saving, this paper puts forward the idea and method of optimizing the design of buildings. Taking the Minzhu community of Hengjiang town, a representative national traditional village in the south of Sichuan province as an example, this paper analyzes and studies the building window form with excellent comprehensive performance based on the local climate characteristics. The simulation software Ecotect was used to simulate the light environment of the optimized building and compare it with the pre-optimized architectural light environment. The results show that the optimized window opening form can not only make the indoor natural illumination reach the design standard of architectural lighting, but also make the indoor thermal environment, wind environment and visual field comfortable and have the effect of energy saving.

Jing Li, Ye Yang, Jian Zhong, Yu Liu
Solar Seasonal Storage Water Heating System for Space Heating of a House in Hangzhou: Simulation Using TRNSYS

Solar energy is sustainable energy for space heating, and the seasonal storage technology is a promising way to solve the mismatch between the annual solar energy abundance and the heating demand. The paper proposes a solar seasonal storage water heating system (Solar-SSWHS) for space heating of a detached single-family house in Hangzhou. Simulation using TRNSYS shows that a system of 40-m2 collectors and a 40-m3 storage tank could meet the space heating demand of the house which has 240-m2 floor area and a heating load of 45 kWh/m2. The indoor temperature was kept above 18.5 °C and averaged 20.4 °C during the heating period (Nov. 15 to Mar. 15). The system achieved a solar fraction of 77%. The rest energy was electricity, which totaled 2361 kWh. The system can save coal by 1.74 toces/year and reduce CO2 emission by 4.52 tons/year and SO2 emission by 0.035 tons/year.

Jie Lu, Guoqing He
Effect of Outdoor Meteorological Parameters on Partial Itemized Cooling and Heating Load of Building

The heating and air conditioning energy consumption account for about 40–60% of the building energy consumption. The research on the relationship between building cooling and heating itemized load and meteorological parameters can further clarify the energy-saving potential of buildings and take concrete measures accordingly. In this paper, a full-year dynamic energy consumption simulation of office buildings was carried out using the typical meteorological year (TMY) generated independently, and the relationship between six meteorological parameters and gain-and-loss of windows and heat gain-and-loss of infiltration is analyzed. The purpose is to seek quantitative relationships between building cooling and heating itemized load and meteorological parameters using principle components analysis (PCA) method. The results show that the synthesis of several related meteorological parameters to represent the outdoor climate conditions has a significant correlation with the heat gain-and-loss of windows and heat gain-and-loss of infiltration, consistent with the analysis of the heat transfer mechanism of building physics. It has been well proven in office buildings, providing a new idea for predicting building energy consumption quickly and accurately.

Honglian Li, Jing Liu, Yao Hu, Ying Yu, Liu Yang
Experimental Study of an Integrated Heating System in a Residential Building Sourced with Multiple Thermal Energies from Solar Energy, Air and Wastewater

Building’s energy efficiency has become a key area in energy saving and emission reduction; thus, heat pumps assisted with renewable energy are of great interest in designing the heating system of buildings. Solar energy is a good renewable energy, but its energy density is relatively low and is not stable. The performance of traditional air source heat pumps is significantly reduced at low-temperature conditions, while the thermal energy of waste bath water in buildings is another alternative heat source although intermittent. Given all of these cases, an integrated heating system with a thermal storage tank was designed, which could collect all the available thermal energy into the tank in real time and serve out the thermal energy for water heating and space heating when being required. Such an integrated heating system was created in our laboratory; its performance was tested and analyzed; results indicated that the whole system had a good performance in energy saving.

Jiamin Fang, Chao Shen, Yiqiang Jiang
Simulation Analysis of Energy and Ventilation Performance of Typical Residential Building Ventilation Modes in Five Climate Zones of China

This paper simulates and analyzes the energy and ventilation performance of a typical residential apartment with different ventilation modes in different cities of China’s five climate zones by EnergyPlus. The ventilation modes are natural ventilation (NV), mechanical ventilation (MV) and hybrid ventilation (HV). Mechanical ventilation system is further categorized to MV1 when all rooms in an apartment are synchronously operated and MV2 when they operated separately on demand. The hourly indoor CO2 concentration and annual energy consumption with and without energy heat recovery device is simulated under different ventilation modes. The results show that natural ventilation will lead to great time percentage when CO2 is over the 1000 ppm limitation under typical window operation behaviors, while mechanical ventilation and hybrid ventilation can meet the limitation; NV system can save energy consumption about 8–36% compared with MV1; MV2 has greater energy saving potential compared with MV1; From the perspective of energy saving percentage applied to MV system, enthalpy heat recovery system and sensible heat recovery system are applicable in severe cold region (Shenyang) and cold region (Tianjin), while enthalpy heat recovery system is applicable in hot summer and cold winter region (Shanghai) and hot summer and warm winter regions (Shenzhen). None is applicable in mild areas (Kunming).

Chen Shi, Haidong Wang, Pengzhi Zhou, Xueni Fan, Tengfei Zhang
Checking Radiation Model Data with the Method of Building Thermal Environment Simulation

Solar radiation data used for the design of building thermal environment in China are seriously deficient; the radiation estimation model is an important way to supplement radiation data. In order to analyze the influence difference in building thermal environment between measured radiation data and radiation model data quantificationally, building indoor temperature, humidity, cooling and heating load are taken as evaluation indexes, and as the same time, meteorological parameters input files with measured data and model data are constructed separately; with the aid of EnergyPlus, building thermal environment simulation was carried out for two types of building—residential building and office building respectively. Simulation results show that the maximum error percentage of building indoor temperature and relative humidity is 6.22% and 11.00%, respectively, on the typical days; the maximum error percentage of annual cooling and heating load is less than 10%. By comparing the simulation results, the influence difference between measured data and model data referring to building indoor temperature, humidity, load and energy consumption can be reflected. It provides reference for designers to use radiation model data in building energy efficiency design.

Ying Yu, Liu Yang, Liqiang Hou, Qimeng Cao
Study on Influence Factors of Cooling and Heating Load and Evaluation Index of Energy Consumption in Inpatient Buildings

The energy consumption of hospital is increasing year by year, and the energy consumed in HAVC accounts for larger proportion. This paper took the inpatient building in hot summer and warm winter climate zone for research object, established the theory model of cooling and heating load, designed the orthogonal simulation experiments and simulated the building load using DEST. This paper aimed to research the influence of beds number, added beds rate, patient accompany system, visiting institution on the building load. The simulation results indicate when the beds number and added beds rate is larger, the patient accompany system is not strict, the building load is larger. It will be smaller conversely. The important order of the influence factor is as follows: beds number > patient’s accompany system > addition beds rate > visiting institution. Beds number and patient accompany system have a remarkable influence on the building load (P < 0.05); the influence of added beds rate is not remarkable (P > 0.05). This paper proposes using per inpatient bed energy consumption to evaluate energy consumption in inpatient building when patient accompany system of the hospital is the same. It will be more scientific.

Liying Liu, Fali Ju, Yanrui Ding
Study on the Performance of Heat Storage System with New Fin Structure

In order to improve the heat transfer performance of phase change materials in latent heat storage systems, four different geometric proportions of rectangular fractal fin structures and a common rectangular fin structure were designed based on fractal theory. The distribution of water temperature field, solid and liquid phase and solidification time were obtained by simulating the solidification process of water in these structures, using sensible heat capacity method. The results show that comparatively high heat transfer was achieved in the cases with fractal fin compared to the common fin, which can easily reduce the solidification time by 54%. In addition, as the length ratio and width ratio increase, the heat transfer performance of the rectangular fractal fin structure will increase. The solidification time of phase change materials (PCM) in RL = 0.5 fin structure can be reduced by 34% compared with that of RL = 0.4 fin structure, and the fin structure of RW = 0.7 can be reduced by 25% compared with that of RW = 0.45.

Tao-tao Chen, Jia-yi Zheng, Yan-shun Yu
Development of a Library for Building Surface Layout Simulator

Available building simulation tools resort to using fixed schedules for modeling occupant behavior (OB), which does not accurately capture its nature. A significant aspect of OB is the movement and sequence of actions with regards to their surroundings. This requires some coherence about the surface layout, including the placement of furniture and the occupant’s interaction with it. There is a need for understanding vital information about the different attributes of the furniture, such as the placement and order of importance. Until now, there exists no such library with this kind of granularity in information. This paper explores the questions with regard to the development of such a library. This includes the description of the type of variables associated with different kinds of furniture, along with the occupant interaction under typical scenarios. The results from this study can be used to integrate the resulting library with building simulation tools and to better understand and develop occupant behavior models.

Masab K. Annaqeeb, Jakub W. Dziedzic, Da Yan, Vojislav Novakovic
Analysis on Energy Consumption and Energy-Saving Retrofit of University Buildings in Hot Summer and Cold Winter Zone of China

Air-conditioning and lighting load in university building energy consumption account for 60% of the total energy consumption. In order to effectively reduce the energy consumption of lighting and air-conditioning, this paper selects a university building in Chengdu as the research object to analyze the energy saving potential of university lighting and air-conditioning load from active and passive measures based on the energy simulation software of EnergyPlus and life cycle theory. The results show that under the premise of meeting the indoor illumination demand, the replacement of the current lamps into more energy-saving lamps can save 27.40% of the total lighting load. Under the actual situation, adding an intelligent control system can save 26.71% of total lighting load, 5.03% of air-conditioning energy consumption, and 14.29% of total energy consumption. Secondly, adding insulation material to the external wall can save 40–60% compared with no insulation material, but different insulation properties have different effects on air-conditioning energy consumption. Considering the energy consumption and cost, 80 mm Rockwool has the best energy-saving effect, and the current condition can save 8.8% of air-conditioning load.

Lili Zhang, Zu’an Liu, Jiawen Hou, Dong Wei, Yuyao Hou, Junfei Du, Qiong Shen
Optimization Analysis of Thermal Performance of Composite Self-insulation Hollow Block

Wall insulation is a scientific and efficient thermal insulation technology, which is an important measure for building energy conservation. Because wall insulation performance is an important factor affecting building energy consumption and indoor comfort, therefore, it is extremely important to optimize wall insulation performance, reduce building energy consumption, and increase indoor thermal comfort. The self-insulating wall is widely used because it has the same life as the building, simple construction process, resource saving, and environmental pollution reduction. In this study, heat preservation material EPS was filled into the cavity of common hollow block to form composite self-insulation hollow block. Through the research and analysis of composite self-insulation hollow block, the thermal performance of composite self-insulation hollow block is optimized. In order to obtain the best filling effect of the thermal insulation material, six different filled positions of composite self-insulating hollow blocks and different filling rates were constructed and placed in the hot and cold test chamber. The internal surface temperature and heat flow of each block were measured by the field detector of heat transfer coefficient of building envelope with JTNT-A, and the thermal properties of six kinds of composite self-insulated blocks were compared and analyzed. The comparison results show that different filling positions and filling rates have great influence on the thermal performance of composite self-insulated block. In this study, by optimizing the thermal performance of composite self-insulation hollow block, a high-quality composite self-insulation hollow block model was obtained.

Wentao Hu, Junfei Du, Zu’an Liu, Chaoping Hou, Yisheng Huang, Gang Zhao
Optimal Design of Axial Flow Fan Using Numerical Simulation

In this paper, Reynolds-averaged Navier–Stokes equations with the standard k−ε turbulent model and Multiple Reference Frame model were used to simulate the performance of axial flow fan. The simulation results were compared with the existing experimental data, and the reliability of the existing numerical simulation method was verified. Then, the variable velocity circulation design method was used to redesign the fan blades. Four types of blades were established using different circulation indexes (m = 0.2, 0.5, 0.7, and 1.0). The performance of the four redesigned fans was calculated by numerical simulation. The influence of circulation index on configuration parameters was studied. Results show that the efficiencies of the redesigned fans were higher than the original one. The efficiency of optimal designed fan could reach 70%, which is 35% higher than the original fan. Besides, the influence of the selected value of design efficiency, lift coefficient, and c/R during the design process on the fan efficiency was also discussed in the paper.

Jialu Liu, Yu Niu, Yanhua Liu
Optimization of Cooling Airflow in Data Center by CFD Analysis in a New Energy Efficient Cooling System Using CO2 as Cooling Medium

In data center, using outdoor low-temperature air as free cooling is one of the most effective ways to increase the energy efficiency of the heat source system. At the same time, optimizing the indoor air organization to reduce the energy consumption of fans is considered as another effective way of saving energy. In this study, a new cooling system for data center by using evaporation and condensation of CO2 as free cooling is proposed. Also, the system is optimized by organizing the cooling airflow with natural convection and small distributed fans on the indoor side. This paper mainly focuses on optimization of cooling airflow, especially that around racks. CFD is used to analyze the temperature distributions and flow distributions by adjusting power of small distributed fans and shape of the cooling unit. The results show that small distributed fans and natural convection can generate the desired distribution of cooling airflow.

Weirong Zhang, Hongye Li, Yifei Bai, Zhaofeng Wang
Development of Prototype Building Model in Beijing Based on Actual Energy Consumption

Building simulation has become more and more widely used in building energy conservation research. Prototype building models that represent the existent building stock especially energy consumption level can make the simulation result closer to the actual situation. There has been several research on prototype building models. This research focuses on prototype building models in China and established prototype building models in Beijing, considering the factor that people in China using the natural ventilation to improve the indoor environment. Through the study of existing research and construction drawings, the prototype building models in Beijing were established, including building type and some input parameters. Prototype building model includes four residential prototypes and eleven commercial prototypes. The simulation results of the prototype building models were compared with the actual building energy consumption data. The result shows that it can be a foundation for building energy consumption simulation research.

Chenxi Gui, Da Yan, Siyue Guo, Jingjing An
The Optimum Research and Case Study of Wind Power Heating Based on Supply and Demand Load Forecasting

Wind power heating is one of the most important methods for reducing the discard wind power. However, one of the key problems is reasonably matching electric power between the output power in a wind farm and building demand heat load, which can improve the economic benefits of the overall project. In this paper, an optimization model includes the wind power prediction model, and demand load model was established, and by which the ratio of discarded wind power was calculated. And under different boundary conditions and optimization objective, the optimal heating area and heat storage tank capacity were obtained. Using this method, a practical project of wind power heating was analyzed in Inner Mongolia Autonomous Region. The analysis result is the ratio of discarded wind reduced to 4.96 % when heating supply using wind power from 14.96% under not heating supply. The annual average of wind farm is raised to 18.47% from 12.51%. This model can improve the efficiency of renewable energy and bring down the ratio of discarded wind, and it can obtain a considerable economic and society benefit.

Chuankai Niu, Zhengwei Li, Renjing Cao
Study on Bath Water Energy Loss of Campus Dormitory Air-Source Heat-Pump Water Heater

South dorms use widely hot water to bath, which is produced by air-source heat-pump water heater. In this study, taking dormitory air-source heat-pump water heater system as the object, the air temperature and wall temperature were tested to get the bath compartment thermal environment, and the outlet temperature and hot water temperature were recorded to obtain the bath water energy loss. The results show that the heat loss of bath hot water has a significant effect on the thermal environment of the compartment and improves the thermal comfort. The average rate of heat loss during the period when the bath hot water touching the body from the outlet to the ground is about 29%, the average heat loss rate of the hot water flowing from the ground to the floor drain is about 71%, and about 64% of the bath hot water is discharged directly into the floor drain. It has practical significance to improve the heat utilization efficiency of bath water.

Liugen Lv, Tao Jia, Wenlian Zhang, Qianqian Jia, Jin Lv, Zhenzhen Jia
Research and Application Status of Energy Conservation in District Energy System and Its Transmission and Distribution Pipeline Network: Review

District energy system has superior properties to the distributed energy system in the aspects of energy saving, flexibility of supply and comprehensive utilization of energy. But the energy losses in the process of energy transmission and the initial costs are not negligible. With the development of the new type of cold and hot producing systems, especially the use of renewable energy, the pipe network system and form have changed. The transmission medium is no longer a single substance, and the supplied energy quality is no longer at a fixed grade. Based on the summary of the research and application results in recent years, this paper discusses some energy-saving measures of district energy system and its transmission and distribution network, summarizes and analyses the system monitoring, heat transfer temperature difference, heat load optimization and multi-heat source coordinated control, respectively, and puts forward more appropriate measures to improve energy efficiency in energy transmission and distribution.

Yuefen Gao, Meng Wang, Chengzhi Wang
New Progress and Thinking on Building Integrated PVT Heat Pump Technology

The solar PVT heat pump technology shows an increasing trend in the field of building energy conservation and renewable energy utilization nowadays, due to its highly efficient and stable time-sharing distributed poly-generation characteristics, as well as its unique advantages in the integration with buildings. This paper analyzed the basic demands of modern buildings with respect to hot water, electricity, cooling, heating and architectural appearance. Several existing problems in the development of solar energy utilization technology were pointed out, as well as three development directions of integration, which refers to the integration of photo-electric and photo-thermal properties, the integration of heating and cooling, the integration of solar modules and buildings. Taking into consideration the perspective of building epidermis, the forms of solar modules which are suitable for the basic architectural design requirements were studied, along with the application of such solar modules and its feasibility. In addition, the design method of the roll-bond-PVT unit and the PVT heat pump poly-generation system were also proposed in this paper. The experimental study was carried out simultaneously, and the main experiment results of the PVT heat pump system were given.

Jili Zhang, Chao Zhou, Shixiang Lu, Ruobing Liang, Jianquan Chen
Experiment Study on Lift and Resistance Wind Energy Fan

At present, wind energy is mainly used for the power generation and its technology has been relatively mature. This paper researches that wind energy is utilized to directly drive the axial fan with the vertical wind turbine, to realize the underground ventilation. This integrated equipment is called wind energy fan (WEF). In this way, the energy loss, which is caused by the repeated energy conversion due to the wind energy generation and the motor-driven fan, will be greatly decreased. According to the rational design and calculation of model schemes, the experiment platform is established to analyze the performance of lift and resistance wind energy fan. Meanwhile, the experiment tests the rotating speed of WEF and the air volume of experiment duct under transmission ratios of 1:1, 1:5.17 and 1:10. The experiment results show that the efficiency of lift WEF is higher than that of resistance WEF. The transmission ratio has a big influence on the air volume of wind energy fan, and the certain transmission ratio should be selected to improve ventilation efficiency. The investigation shows this scheme is an effective wind energy technology to realize the active utilization of wind energy in underground engineering ventilation.

Yuling Wu, Ziyun Wang, Runsheng Qi
Study on Re-Independence of Flow Structure in a Flat Large-Space

Locomotive inspection and repair shed and underground garage belong to typical flat large-space on which there are few studies about Reynolds number independence (Re-independence). In order to provide theoretical basis of scale experiment for such subjects, in this paper, a 1:40 reduced scale models of a flat large-space are numerically established, and Re-independence of flow pattern are investigated using a Computational Fluid Dynamic (CFD) method. The main content includes: (1) Based on the reduced scale model, the vertical profiles of dimensionless velocity are compared with Reynolds number increased from 85 to 12,750. (2) A dimensionless number, relative change rate of velocity (RCRV), and a criterion of RCRV less than 5% are proposed to quantitatively calculate critical Reynolds number (Recrit). The results show that the suggested Recrit of the flat large-space studied is 5950.

Xuehai Zhu, Lu Feng, Ran Ju, Di Mu, Naiping Gao
Experimental Study and Techno-Economic Analysis of Household PVT Heat Pump Poly-Generation System

The PVT heat pump poly-generation system has become a research hotspot in the field of building energy conservation and renewable energy utilization, due to its high efficient and stable time-sharing distributed poly-generation characteristics. In this paper, the household PVT heat pump system is selected as the research object, aiming to meet the building’s various energy demands for heating, cooling, power and hot water, by establishing one set of PVT heat pump poly-generation system. The system operating principles and the design method of roll-bond-PVT unit are introduced in detail. The experimental investigation on the PVT heat pump system was carried out, and the main poly-generation performance during summer was given. The concept of electro-thermal number is proposed to illustrate the design principle and configuration method of household type system. In addition, the techno-economic analysis of the household PVT heat pump poly-generation system was developed. The key economic indexes were proposed, and the technical economy of the system was analyzed and compared. The research results of this paper are of great reference value for the future application of the household PVT heat pump poly-generation system.

Chao Zhou, Jili Zhang, Ahmad Riaz, Ruobing Liang
Repair Method of Chiller Power Consumption Monitoring Data Based on Multiple Linear Regression Model

With the gradual advancement of energy-saving work in public buildings, the number of energy monitoring systems continues to increase. However, due to the low level of information management, quality problems are common in monitoring data; there are cases where data is missing or abnormal, which hinders the well progress of energy conservation. Therefore, the method for quickly and accurately repairing problem monitoring data needs to be studied. The core part of the power consumption of HVAC is the freezing station, in which the power consumption of the chiller occupies a major part, needs to be concerned. This paper proposes to repair the data by establishing energy consumption model. The research object is the chiller of a campus education office building. Firstly, the factors that affect the power consumption of the chiller are mastered. Then, the operating parameters are simulated by e-Quest software, and a multivariate regression model of power consumption with meteorological parameters is established. Finally, the model is used to repair the problem data. The results show that the correlation coefficient between the leaving supply temperature of water and power consumption is about 0.9, which has the greatest impact and is of great significance to the retrofit of the systems. And, the repair accuracy for missing data reaches 2–3%, indicating that the method is fast and effective and can be applied online.

Zhuyue Chai, Tianyi Zhao, Liangdong Ma, Jili Zhang, Mingsheng Liu
Investigation on Energy Saving Potential of a Vertical Greening System in Hot Summer and Cold Winter Areas in China

As a new type of greening method, vertical greening can not only solve the problems of shrinking green space, poor air quality, reduce the heat island effect on urbanization, but also affect the annual building energy consumption. In this paper, the energy saving potential of vertical greening in China’s hot summer and cold winter regions is investigated through comparative experiments between a vertical greening room and a reference room. During winter, the total power consumption of the reference room is 1.22 times that of the vertical greening room. The energy saving rate of the vertical greening system is concluded to be approximately 18%. During summer, the total power consumption of the reference room is 1.33 times that of the vertical greening room. The energy saving rate of the vertical greening is approximately 25%.

Hang Tan, Zhuoyu Yang, Xiaoli Hao, Qingwei Xing, Yaolin Lin, Xianping Liu, Jinhua Hu
Study on Effect of Different Wall Insulation Structures on Building Energy Consumption in Low Latitude Region: A Case Study in Qionghai, China

Qionghai is located in the low latitude region where the solar altitude angle is high. It is a typical climate with high temperature, high humidity, intense solar radiation, and small daily temperature variation. Under such climate conditions, designing optimal wall insulation structures is critical for achieving building energy saving. This paper takes a hotel building as a case, to simulate energy consumption of the building with different wall insulation structures in Qionghai by EnergyPlus software. The results show that building envelope insulations have obvious insulation effect, and the energy saving effect of external insulation and sandwich insulation is better than internal insulation. Internal insulation decreased the cold load index of 10.34%, while external insulation and sandwich insulation, respectively, reduce the cold load index of 12.21 and 12.34%. The energy saving effect of the three wall insulation structures would decrease with the increase of autoclaved lime-sand brick layer thickness.

Chenrong Yu, Jingchao Xie, Peng Xue, Jiaping Liu, Ying Ji
Research on Electricity Consumption Characteristics of Centralized Air Conditioning Units for Data Restoration of Building Energy Consumption Monitoring Platform

The air handling unit (AHU) is an indispensable end device in the central air conditioning system; its true continuous energy consumption data has important reference value for energy-saving renovation and is a key part of building energy efficiency. However, the AHU operating electricity consumption of the current energy monitoring platform generally has problems such as data loss and data anomalies. To this end, this paper analyzes the correlation of the electric characteristics of AHU and establishes the characteristic curves of the staff rate, the same moment outdoor temperature, and unit electricity consumption. It lays the necessary preconditions for obtaining the acquisition parameters and improving the energy consumption monitoring platform.

Terigele Ujeed, Tianyi Zhao, Liangdong Ma, Mingsheng Liu
Prediction of Building Stock Energy Demand

Recent years witnessed an increasing interest in the prediction of building energy demand at large-scale. The prediction of large-scale building (or building stock) energy use is essential for energy policy development, energy management, urban development decision, and distributed power generation. However, it is not a simple task to estimate large-scale building energy consumption because of significant uncertainties in building information for a variety of critical characteristics. Modeling every single building within a building stock is impractical, and proper methods are hence inevitable to reduce modeling efforts and simulation time. This study presents a stochastic building stock energy modeling approach using archetypes and Bayesian calibration. The paper introduces the procedure of the proposed method and then demonstrates and validates the method with a campus-scale application with 80 buildings. The predicted campus-scale building energy demand matches the measured energy data and provides much comprehensive knowledge on the building performance with estimated stochastic distributions of building energy usages.

Hyunwoo Lim, Zhiqiang (John) Zhai
Uncertainty Analysis of Urban Building Energy Based on Two-Dimensional Monte Carlo Method

Energy performance of urban buildings is affected by a number of inherent uncertain factors, including weather conditions, internal heat gains, occupant behavior, and HVAC systems. These uncertain variables lead to variations of energy use in urban buildings. Therefore, this paper implements a two-dimensional Monte Carlo method to properly assess variations of energy performance of urban buildings by considering two types of uncertain factors (aleatory and epistemic). In this study, aleatory uncertainty refers to inherent randomness of input variables in building energy analysis; whereas, epistemic uncertainty refers to retrofit variations to improve energy efficiency for urban buildings. The results indicate that the two-dimensional Monte Carlo technique can consider two types of uncertain factors to quantify the variations of energy performance in urban buildings. It is also found that the aleatory uncertainty of energy performance is larger than the epistemic uncertainty of energy use in this study, which indicates that more attention should be paid on aleatory uncertainty to reduce its influence on energy use.

Xing Fu, Wei Tian, Yu Sun, Chuanqi Zhu, Baoquan Yin
Research on Energy Consumption Data Characteristics of Office Building VRV Air Conditioning Outdoor Unit Based on Energy Consumption Monitoring Platform

For VRV outdoor unit, the energy consumption models of air conditioning are not preferably fit for the identification and repair of data in the energy consumption monitoring platform. New characteristic models are established to provide useful assist in the identification and repair of data in this paper. Firstly, the energy consumption data of VRV outdoor unit are classified into different energy consumption modes. Secondly, the relation between data and the influencing factors of VRV outdoor unit is analyzed and the correlation coefficients are calculated. Then the influencing factor in which correlation coefficient is greater than or equal to 0.3 is selected as input variables in characteristic models. Finally, the characteristic models are established and calculated values are reckoned. The maximum average relative error between calculated value and the actual energy consumption value is within acceptable limits under different energy consumption modes.

Liangdong Ma, Fengmei Lu, Jili Zhang, Yiying Xu
Evaluation Methods and Index System for Data Quality of Public Building Energy Consumption Monitoring Platforms

The process of the constructing and operating building energy consumption monitoring platforms (BECMPs) has last for more than a decade in China. In the meantime, a lot of problems occurred, such as data loss and data anomaly. However, there is lacking method to automatically measure the data quality of BECMPs. Most data problems can only be discovered by human checking, which is often delayed, and the severity is often unclear, resulting in restriction to further data utilization. Based on previous research on the causes of data loss and data anomaly, this paper put forward an index system to evaluate the data quality of BECMPs. The index system targets the data quality itself as well as the designing, constructing, debugging, operating and maintaining process of BECMPs, which enable the maintenance personnel to have a clear knowledge of the data quality and help them keep the system in an optimal state.

Huiyu Yan, Liangdong Ma, Jili Zhang
Energy-Saving Effect and Mechanism of Heating Setting Temperature Decreased by 1 °C for Residential Buildings in Different Cities

Heating setting temperature (HST) is a key and controllable parameter affecting total heating energy usage. In this paper, characteristic temperature method (CTM) is used to pre-estimate the heating load of a residential building for seven cities under different climatic conditions when the HST decreases by 1 °C. The energy-saving effect is discussed to clarify the internal mechanism of the difference between the energy-saving amount (ESA) and ratio (ESR) from two perspectives. The results show that when the HST drops by 1 °C, ESA and ESR will vary widely. The colder region is, the higher ESA can reach, but the lower ESR will be. Although heating hours differ by three times in different regions, the overall trend is that the hourly load reduction rate increases rapidly with the increasing outdoor dry bulb temperature, while it increases exponentially with the decreasing hourly heating load. This study can provide reference for standard determination and building energy saving from the resident behavioral aspect.

Shurui Guo, Hanyu Yang, Yin Zhang, Enshen Long
Comparative Analysis of Air-Cooled Precision Air Conditioners and Water-Cooled Precision Air Conditioners

This paper compares air-cooled and water-cooled precision air conditioners used in computer rooms from six aspects: energy-saving measures that can be adopted, system safety, system investment, system operation and maintenance, load change adaptability, and system energy efficiency. Results showed that the air-cooled precision air-conditioning system has excellent performance in terms of safety, initial investment, operation and maintenance requirements, adaptability to load changes, and energy efficiency compared to water-cooled precision air-conditioning systems; air-cooled precision air conditioners cannot adopt integrated energy efficiency measures for cogeneration. This paper offers a reference for the selection of precision air conditioners for data centers.

Huifang Liu, Zhixian Ma, Mingsheng Liu
Evaluation of Radiant Heating and Cooling Terminals Based on Structural Thermal Resistance

Radiant heating and cooling terminals have different structural forms that can significantly influence its heat transfer performance. However, the existing methods evaluating thermal performance of radiant terminals did not reflect the effects of the structures. This study uses the concept of average thermal resistance based on heat transfer model. Four common radiant ceilings were tested under temperature conditions of 26 °C and 21 °C through laboratory experiments. Their structural thermal resistance values were calculated. The results show that structure thermal resistance can reflect the influence of terminal structures on the heat transfer performance. The error is less than 10%, which is good enough to meet the engineering application requirements.

Xiang Zhou, Yunliang Liu, Shaochen Tian, Maohui Luo, Lili Zhang, Yongli Yuan
Carbon Performance Evaluation of Urban Buildings Using Machine Learning-Based Energy Models

Because of the large number of buildings and the complexity of influencing factors in urban building energy analysis, the computational cost of large-scale energy models for urban buildings is high. Hence, this paper implements a machine learning-based approach to assess carbon emissions of urban buildings. A campus in China is used as a case study to demonstrate this approach, including four steps: automation of construction of engineering-based energy models in a geographic information system (GIS) environment, construction of a matrix of input and output data, creating machine learning models, and sensitivity and carbon emission analysis of urban buildings. The results indicate that this method can effectively assess carbon emissions for urban buildings with different energy-saving measures based on machine learning energy models. The accuracy of machine learning models should be carefully evaluated before implementing them in carbon emission analysis for urban buildings.

Yunliang Liu, Wei Tian, Xiang Zhou
Study on the Degree and Mechanism of Solar Shading Impacts from Rooftop Structures in the Solar Collector Layout Area

The authors defined four physical quantities’ shading rates, namely the time integral of insolation area, the direct solar radiation, the diffuse solar radiation, and the incident solar radiation. Taking a practical project’s roof in western Sichuan as an object, this paper studied shading rates from roof structures on the solar collector layout area in the heating season and quantified shading impacts from different time dimensions. The results show that shading rates are maximum in the coldest month, December, and that is smaller in the early and late of the heating season. In December, shading rates of the time integral of insolation area and the incident solar radiation are 53% and 30%, respectively, which indicate that shading effects of roof structures cannot be ignored in the heating system design. The research results are of great reference value for the installation optimization of collectors and the reasonable matching of the heating system.

Luting Xu, Enshen Long, Xuefei Xiao, Ziyun Wang
The Effect of Internal Load on the Selection of Heat Radiator

The selection of heat radiator has a non-negligible impact on the heating effect of the building. The rationality of the radiator selection will directly affect the project cost and actual heating effect. Building load calculation is an important part of radiator selection. The goal of this paper is to investigate the effect of internal load on the selection of radiator. Taking the terminal heat radiator in one dormitory room in Beijing as the example, the simulation was performed using DeST-h software based on the actual outdoor meteorological parameters. Room heat loads considering the room’s internal load disturbances and not considering the room’s internal load were calculated separately, by which the radiators were selected, respectively. The designed supply-return water temperature is 75/50 °C. Then DeST-h software was introduced to simulate the heating effect of the room. It was found that the room temperature after heating in consideration of room’s load disturbances can meet the comfort requirements, and the indoor temperature without considering the internal load disturbances in the room may be excessively high. For the rooms located in the north and south directions, the radiator’s area can be saved by 18.9 and 20.3% when considering the room’s internal loads. The significance of this research is that it has an important role in the correct selection of the radiator, which can save the project cost, reduce the heating energy consumption, and provide a comfortable indoor thermal environment.

Guoyi Xu, Yiwen Jian
Experimental Study on Albedo of Solar Radiation in Different Underlying Surfaces in Western Sichuan Plateau

In this paper, the albedo of several common underlying surfaces in the western Sichuan Plateau is tested experimentally and the solar radiation albedo of different underlying surfaces is obtained by analytical calculation. The results show that the surface albedo of grassland, cement brick land, and sandy land is directly related to the instant total solar radiation received on the underlying surface. The greater the total solar radiation received on the surface, the greater the solar albedo is, and vice versa. While the albedo of water surface is negatively correlated with the total solar radiation intensity, that is, the smaller the total solar radiation intensity is, the larger the albedo is, and vice versa. The average albedo of grassland, cement brick surface, sandy surface, and water surface was 0.32, 0.47, 0.49, and 0.33, respectively. The research results fill the gap of basic data of active and passive solar energy applications in plateau area.

Qiancheng Shan, Enshen Long, Yin Zhang, Fei Gao, Ziyun Wang
High Energy-Efficient District Cooling System and Its Engineering Applications in India

This paper introduces the studies and experience learned in district cooling project development in developed countries and adaptation process in India for city-level rapid assessment. There are five pilot Indian cities chosen to go through all the process of rapid assessment so as to outline the barriers, challenges, and potential to develop high energy-efficient district cooling system. The paper also instructs the tech-eco analysis tools for rapid assessment, which is developed by the UNEP District Energy in Cities Initiative and adapted in India. According to the results, the economic and technical boundaries of implementing district cooling systems are outlined.

Zhuolun Chen, Lily Riahi, Benjamin Hickman
Comparison of Nuclear District Heating Technologies in Russia and China

This paper presents the comparative analysis of nuclear district heating (NDH) development in Russia and China, including background and recent development of NDH, comparison of main technologies in the field of NDH, and countries’ development strategies of NDH. Even though USSR had the ambitious plans of NDH development, Chernobyl disaster and the dissolution of USSR were the main reasons of ex-USSR and Russia NDH development cease. By now, NDH in Russia is mostly presented by steam extraction from turbines (SET) of nuclear power plants (NPP). To reduce the high air pollution in northern China, it is essential to seek for alternative clear energy source to substitute coal, which is mostly used for country’s district heating (DH). One of that new energy source can be NDH. For rational development of NDH, it is necessary to analyze and compare NDH technologies in different countries.

Aleksandr Solomykov, Jinling Zhao
Sensitivity Analysis on Influence Factors of Comprehensive Energy Planning for Low Carbon City in China

In order to alleviate the pressure of urban energy and environment, more and more attention has been paid to the comprehensive utilization of energy in the process of urban planning. In this paper, according to Delphi method, a questionnaire of influence factors is designed. Sixteen major influence factors are extracted from dozens of preliminary influence factors by expert research. Sensitivity of the sixteen influence factors is analyzed using R data analysis software, including importance analysis, correlation analysis, and cluster analysis. Hierarchies of the sixteen influence factors in planning and design field, technology field, and management field are established respectively. The results show that sixteen influence factors are all divided into four levels in three fields; influence factors in the first three levels vary with the professional background of experts; however, low carbon energy saving policy and low carbon concept and technology are all included in the first level; especially the fourth level contains the same factors. Based on the results, relevant countermeasures and suggestions on comprehensive energy planning for low carbon city in China are put forward: Firstly, stress on the study of policy and master planning; secondly, formulate the planning idea of “Multiple Plans Integration”; thirdly, control low carbon indicators in construction, transportation, and industry; fourthly, ensure the continuity of compilation, implementation, and management of comprehensive energy planning.

Li Zhu, Jiqiang Zhang, Yang Yang, Zhexing Yan, Qi Liu, Yong Sun
Influence of Air Curtain Characteristics on the Capture Performance of Range Hood

Range hood is a common ventilation appliance applied in a kitchen for maintaining healthy environment. This paper numerically studied the effect of air curtain on capture performance of a range hood, which was equipped in a residential kitchen chamber of 3.5 m * 2.7 m * 2.4 m. Two key parameters of air curtain, air-supply velocity and angle were investigated for improving the capture performance with CFD methods. Only when both the air-supply velocity and angle were well defined simultaneously, could the range hood have a good capture performance. When air-supply angle is 4°, air-supply velocity is recommended at 2.0–2.5 m/s. When air-supply velocity is 4.5 m/s, air-supply angle is recommended at 10°–14°. In the above situation, the range hood has better capture performance. The findings showed that the air curtain with reasonable air-supply velocity and angle could effectively improve the capture performance of range hood and protect the cook.

Lipeng Lv, Changsheng Cao, Jun Gao, Yongzhe Meng, Xishun Ai, Qigao Gai
An Improved Model for Optimal Design of Building Integrated Photovoltaic Thermoelectric Systems

Photovoltaic and thermoelectric modules can be incorporated together to realize better energy solution for building. The optimal design of building integrated photovoltaic thermoelectric systems (BIPVTE) becomes an important issue and previous methods cannot capture the dynamic feature and exact optimum point of the system. This study proposed a new and improved model which can locate the optimization design point with explicit way and considered the solar energy variations. Numerical results revealed that these method and model are effective and helpful for the design of BIPVTE systems.

Xiaosong Su, Ling Zhang, Yongqiang Luo, Zhongbing Liu, Yongwei Luo, Jinbu Lian, Jing Wu, Zhenghong Wu
Experimental Study on a Facade-Built-in Two-Phase Thermosyphon Loop for Passive Thermo-Activated Building System

A novel facade-built-in thermosyphon loop (TPTL) for passive thermo-activated building system was proposed in this paper. The feasibility and effect of the filling ratio as well as the heat source temperature on the operation performance were investigated through the experimental method. Results show that the filling ratio has a great impact on the performance of the facade-built-in TPTL. There exists an optimal filling ratio to achieve a better heat transfer performance under different operation temperatures. The filling ratio of 88% is found to be the optimum filling ratio for the prototype based on the performance indicator of the total heat transfer resistance. Under the optimum ratio condition, the heat transfer rate of the facade-built-in TPTL could reach up to about 132–300 W when heat source temperature maintains at 35–55 °C.

Li Zhu, Yang Yang, Jiqiang Zhang, Sarula Chen, Yong Sun
Study on the Influence of Different Positions of the Air Inlets in the Kitchen on the Air Supplement Effect

When the hood is working, closing the kitchen doors and windows, using organized natural ventilation, can reduce part of the kitchen energy consumption and is more conducive to the discharge of kitchen pollutants. This study placed a natural air vent on the kitchen ceiling. In the case of the same hood exhaust volume and air supply port area, the choice of air supply port position has a great influence on the airflow organization of the hood. In this paper, several kitchens that installed air inlets at different positions were used as simulations in the CFD software. For the turbulent flow of indoor airflow, the turbulent standard k-ε model is selected. And with the hybrid meshing method, control the finite volume method is used to discretize the calculation region. The study found that in the kitchen model of this study, the air filling effect was the best when the air inlet was 1 m from the reference wall. When the distance is long, the airflow of the air supply port has little interference to the hood. When the distance is relatively close, the airflow of the air supply port promotes the capture of the pollutants, and the superposition of the two effects determines the final air filling effect.

Dan Yi, Lianjie He, Lipeng Lv, Jun Gao
Evaluating Thermal Performance of Oval U-Tube for Ground-Source Heat Pump Systems from in Situ Measurements and Numerical Simulations

A new-shaped U-tube with an oval cross-section has been developed to boost the heat transfer inside the borehole heat exchanger and to reduce the heat exchanger depth and the drilling cost. In addition, it could fit efficiently inside tight boreholes, so it is fitting for installing GSHPs at urban areas. This research evaluated the effectiveness in situ by thermal response tests at total 20 borehole heat exchangers in three sites, Japan. The in situ borehole thermal resistances were about 10–30% smaller with the oval U-tube than the circle U-tube. However, the spacers had an imperceptible impact probably because of the soil pressure to the U-tubes. Also, transient numerical CFD simulations were carried out to calculate the long-term performance of a household GSHP system with oval U-tubes. It indicated that the required lengths of a borehole heat exchanger could be reduced by about 14% in the fine soils and 15–19% in the coarse soils.

Yoshitaka Sakata, Ahmed A. Serageldin, Takao Katsura, Motoaki Ooe, Katsunori Nagano
Development and Experimental Validation of a Finite-Difference Frequency-Domain Model for the Exhaust Air Insulation Wall

The exhaust air insulation (EAI) wall is a new type of external wall which is mainly composed of an air-permeable porous material, a ventilated cavity, and an exterior protection structure. The EAI wall can reduce the cooling/heating load through the wall by recovering the low-grade thermal energy of exhaust air. A finite-difference frequency-domain (FDFD) model was proposed to predict the thermal response of the EAI wall. The computation time of the FDFD model is lower than that of the finite-difference time-domain (FDTD) model. The experimental test of the EAI wall was conducted in a full-scale test cell under predefined boundary conditions. The experiment results were compared with the calculation results by the FDFD model. Results indicated that the temperatures of the EAI wall calculated by using the FDFD model show good agreement with the measurement data.

Liao Li, Chong Zhang, Jiaqi Hu, Wenjie Gang, Jinbo Wang
Experimental Study on Electrical Power Generation and Natural Daylighting Illuminance Due to Building-Applied Photovoltaic Façade Application

Office buildings consume a huge amount of energy which is responsible for greenhouse gas emissions as well. On the other hand, the photovoltaic systems play a copious role in building energy load reduction and at the same time supply clean electrical energy to the building. In this study, south-facing applied photovoltaics system was built to the exterior of the existing office building with a 0.5 m air gap having 13 m × 4 m dimensions with 8 × 4 of array layout to form building-applied photovoltaic (BAPV). The thermal response of this BAPV system was studied under real outdoor conditions for Dalian. Moreover, the daylighting illuminance (lux) was measured at the working plane inside the office room due to the effect of BAPV façade construction. The 19.8% of power generation efficiency was found for such custom-made PV modules. In addition, the daylighting illuminance was found to be 300–500 lx till 14:30 and afterward led to decrease and have to switch on the artificial daylighting for indoor comfort.

Ahmad Riaz, Jili Zhang, Chao Zhou, Ruobing Liang
Train-Induced Unsteady Airflow (TIUA) Characteristics in Subway Ventilation Network

Nowadays, subway is rapidly developing globally; meanwhile, it costs huge energy. Train-induced unsteady airflow (TIUA) takes a crucial influence on the environment and energy consumption of subway. In the present study, 1D simulation was conducted using IDA tunnel software to analyze the TIUA characteristics of various components in subway ventilation network, such as platform, piston vent shaft, and bypass duct. The results demonstrate that the platform had the diverging and converging effect on the TIUA, and the converging effect was more outstanding with the piston vent shafts and bypass ducts closed condition. Moreover, bypass ducts at the upstream tunnel of subway stations mainly exerted a diverging effect on the TIUA, whose time-average diverging coefficients were approximately 0.16. In addition, piston vent shafts and bypass ducts at the downstream tunnel primarily took a converging effect on the TIUA; the time-average converging coefficients of the piston vent shaft were approximately 0.18 with the bypass ducts open and approximately 0.29 with the bypass ducts closed, respectively; and the time-average converging coefficients of the bypass duct were approximately 0.40. In addition, this study will provide meaningful design guidance for designer and enormous energy-conservation potential for subways.

Xin Zhang, Jiangyan Ma, Angui Li
A Simulation Study on the Hydration of Magnesium-Based Thermochemical Heat Storage System for Residential Buildings

Thermochemical heat storage system has a great potential due to its advantages of high heat storage density and long storage time. In this paper, a thermochemical heat storage system is designed based on Mg(OH)2/MgO and a two-dimensional mathematical model of exothermic process of the thermochemical energy storage reactor is established, which can be applied in residential buildings. The heat storage and exothermic processes of the heat storage units (HSU) are investigated by numerical simulation. The third boundary condition is adopted and the temperature change of the heat transfer fluid (HTF) in the channel is considered. After modeling the whole system, some parameters of the system are optimized, including the size of HSU, the inlet temperature of HTF, and the pressure of reaction bed, which is helpful to guide the design of thermochemical heat storage equipment in future. In addition, the results reveal that the reaction limit is in good agreement with previous literature and the energy storage density of magnesium-based thermochemical energy storage system is much higher than ordinary phase change materials such as paraffin. The heat storage system is expected to be a new type of heat storage system.

Yi Wang, Zhenqian Chen
Research on Evaluation Index System of District Energy Systems

With the rapid development of district energy system, a relatively perfect evaluation system becomes a top priority in making a promising system with multiple complementary functions recognized by the government and the public. Based on the characteristics of district energy, the district energy evaluation index system is established from energy efficiency, economy, and environment. Traditional evaluation indicators have been filtrated and optimized. The indicators adopt an improved analytical hierarchy process to determine the weights. The reference district energy system grading standard is presented in view of the score of the relevant energy system. Finally, the proposed evaluation system is used to assess an actual project. The results show that the proposed evaluation system has good maneuverability and can guide the optimization of the system.

Tianjie Liu, Wenling Jiao, Lemei Ren, Xinghao Tian
Research on Thermoelectric Coupling Model of Photovoltaic Wall Based on Equivalent Circuit Model and Its Thermal Characteristics

This paper provides a method for thermoelectricity coupled simulation of the photovoltaic wall. Based on the equivalent circuit model and the relationship between the operating temperature of photovoltaic modules and the thermal characteristics of photovoltaic wall, a one-dimensional unsteady heat transfer model considering multiple boundary conditions is established, and the operating temperature of the photovoltaic module is calculated, then the value is again coupled into the dynamic power model of photovoltaic modules to achieve the accurate simulation of the photovoltaic power generation performance and the heat transfer process of photovoltaic wall. The above decoupling and recoupling processes between heat transfer and power generation performance fully consider the effects of multiple environmental factors and multiple boundary conditions on the power output and unsteady heat transfer of the components, as well as the coupling between thermal and electrical properties. By simulating the power generation performance and thermal performance of photovoltaic wall in winter and summer in Nanjing, the correctness of the proposed method was preliminarily verified, and the problems of photo-electricity-heat combined simulation of the solar photovoltaic wall are solved.

Wenjie Zhang, Shengbing Ma, Ziqiang Huang, Bing Bai, Xiufeng Tian
Space Heating Management for Solar Heating System with Underground Pit Storage

The solar heating system coupled with seasonal thermal energy storage (STES) is a promising solution to solve the seasonal mismatch between the solar energy supply and heating demand. A pilot solar heating system integrating with a 3000 m3 underground pit seasonal storage (UWPS) was built in Hebei, China. A TRNSYS model was established to analyse a new space heating management coupling with the mature district heating methods considering the outlet temperature of the UWPS. The simulation results showed that on the basis of maintaining the set indoor temperature 18 ± 1 ℃, the application of proposed space heating management to the UWPS-solar heating system is good and the solar fraction is 85.6% at the mean heat load of 40 W/m2, with the management of the fluctuation of the heat source, ambient temperature and the heating load.

Xiaoxia Li, Zhifeng Wang, Jinping Li, Ming Yang, Yakai Bai, Longfei Chen
Metadata
Title
Proceedings of the 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2019)
Editors
Prof. Zhaojun Wang
Prof. Yingxin Zhu
Prof. Fang Wang
Prof. Peng Wang
Prof. Chao Shen
Prof. Jing Liu
Copyright Year
2020
Publisher
Springer Singapore
Electronic ISBN
978-981-13-9528-4
Print ISBN
978-981-13-9527-7
DOI
https://doi.org/10.1007/978-981-13-9528-4