Cold Climate HVAC 2018

In Tuolluvaara, just outside Kiruna in northern Sweden, NCC has worked with Kiruna Municipality and Tekniska Verken i Kiruna AB to build the passive house project “Sjunde Huset”, a full-scale demonstration of a low-energy semi-detached dwelling for a sub-arctic climate. Based on NCC’s Cube concept for energy-efficient houses, the semis are built to FEBY12’s passive house criteria. The building serves as a test bed for the design, material choices, technical solutions and construction processes associated with energy-efficient construction in a sub-arctic climate. Features include a system for mechanical ventilation with heat recovery (MVHR). The building project has been prompted by the major social changes taking place in Kiruna and Gällivare and the newly tightened EU directives on energy consumption. This article presents the building and its energy-efficient solutions, along with measurements of the buildings heat loss factor (HLF), the ventilation system’s efficiency, and the specific energy consumption. We can report that Sjunde Huset meets FEBY12’s passive house requirements and that it is perfectly possible to build low-energy homes in a sub-arctic climate, with the potential to reproduce it at a lower production cost.

A structural insulated panel (SIP) demonstration house was commissioned in Iqaluit, Nunavut, Canada, along with instrumentation to assess thermal performance. Instrumentation panels were developed to perform in situ measurements. Laboratory testing was completed to confirm the accuracy of the instrumentation panels and measure the thermal resistance of the insulation panels at various mean temperatures. In situ testing confirmed the variability in R-value with temperature seen in laboratory testing. The thermal resistance decreases with decreasing temperature, which is of concern in this particularly cold climate. Regardless, the envelope thermal performance was consistently superior to a 2″ × 6″ (38 mm × 89 mm) wood stud construction with batt insulation. The in situ R-value of the SIP varied from approximately RSI 4.4 (R25) to RSI 5.3 (R30) between October, 2016 and April, 2017. The cumulative apparent R-value was also calculated according to the method defined in ISO 9869, resulting in values of RSI 5.07 (R28.8), 4.84 (R27.5), and 4.97 (R28.2) for the wall, floor, and ceiling modules, respectively.

A demonstration house was built and commissioned in Iqaluit, Nunavut, Canada. The purpose of this work is to evaluate the energy consumption of the high performance building, while considering the unique social, economic, and logistical challenges for such a remote location. At 4.5 m by 5.4 m internal dimensions, the building has approximately 24 m2 of floor area and is a 15 cm thick structural insulated panel (SIP) system with an R-value of 24 (RSI 4.23) at a panel mean temperature of 0 °C. A full year of monitoring has been conducted thus far, between April, 2016 and April, 2017. The cold climate required heating during all but a few hours of the year, with the outdoor ambient temperature ranging from −39 °C to +21 °C and a total of 9540 °C heating degree days for calendar year 2016. Daily heating energy consumption ranged from a peak of 30.4 kWh in the winter down to a minimum of 0.9 kWh for a small number of days during the summer when outdoor ambient temperatures neared 20 °C. The total heating electricity consumed for the period of April 25, 2016 to April 25, 2017, including electronics and lighting, was 4945 kWh. Based on the floor area, the building had an energy use intensity of 206 kWh per m2.

Energy savings with building’s automation is related to the functionality of the building’s automation system, equipment automation level, control algorithms and user-selected operating parameters. It is difficult and time-consuming process to customize each of these algorithms to a level, which would ensure the rational use of energy resources. To increase the adjusting quality that controls building’s engineering system it is necessary to implement new advanced methods, technologies and control algorithms within building’s automation system. This work presents the method of creating self-learning system, which is capable of detecting negative influences of different control algorithms. This self-learning system also provides error detection in engineering systems of the building. The system was designed in Matlab and Simulink programming environments. The article also describes the architecture of designing a complex wireless network system with real time (online) connection, including automatics and building’s engineering systems. This complex system is also capable of collecting data to perform an effective intellectual analysis.

As the newly built and renovated buildings consume less energy for heating needs, due to better and thicker insulation, the relative energy consumption for ventilation increases. This leads to necessity for increased effectiveness of ventilation systems, but such systems are more expensive in installation therefore the most economically feasible solution must be found in each case. A specific attention should be paid to such unclassified buildings as dormitories and barracks where occupancy profile and density differs from residential buildings which are already widely analyzed. This paper presents study results of cost analysis for different ventilation strategies for case study multi-story apartment building in Latvia and Estonia. The compared ventilation strategies include natural ventilation through windows, natural ventilation by having inlet valves with natural exhaust, hybrid ventilation with inlet devices in walls and mechanical exhaust, decentralized mechanical ventilation with room based heat recovery, decentralized mechanical ventilation with apartment based heat recovery and building based centralized ventilation system. For each of these system types installation costs are estimated, based on necessary equipment and actual market prices. Afterwards annual running and maintenance costs are calculated and obtained data compared to select the optimal solution. The results show that the most cost effective system in longer time period is centralized ventilation system which serves whole staircase. Although the simpler solutions like natural or hybrid ventilation systems with air inlets through walls and mechanical exhausts are initially cheaper the energy costs to heat up the incoming air are high and therefore cost inefficient in longer time period.

Compared with indirect-contact heat exchanger, gas-water direct-contact heat exchanger has superiority of decreasing metal heat-exchange surface, small temperature difference and volume, less investment and good antiseptic effect. This paper studies the droplets movement characteristics and performance of gas-water heat and mass transfer. The gas-water direct-contact heat transfer differential equation has been set up to obtain temperature distribution of flue gas and water. The main factors are also analyzed. In this paper, a direct-contact heat transfer model is established for a project, and the results of theoretical calculation and engineering operation are compared. The model has been verified.

Finland has around half a million summer cottages. An increasing demand exist for using these cottages also in other seasons. The influence of constant output heating is studied for energy saving purposes while avoiding moisture damage in the cottages. The proposed type of heating requires only a fraction of amount of electrical energy in comparison with conventional heating. Field measurements, which are presented in current paper, aim at indicating the actual moisture conditions in unoccupied Finnish summer cottages. Field measurements in seven non-insulated massive log walled cottages in Tampere region (Finland) have been performed during 2007–2009. Based on the values of indoor and outdoor RH (at one-hour interval) the monthly average differences between indoor and outdoor water vapour content were determined. Prevailing conditions of moisture deficit were found in summer cottage case buildings during the measurement period. These results oppose to the usual conditions of moisture excess in Finnish residential buildings. Despite the difference in moisture conditions the envelope structures in summer cottages and in residential buildings are often similar.

The main aim of this work is to analyse the energy saving potential and peak power impact resulting from the temperature setback approach. This paper analyses low energy buildings incorporating high-efficiency heating systems with limited power, as additional power for district heating and heat pump systems will need costly investments. The setback efficiency is estimated for different types of heating systems. Underfloor heating is compared to radiators both for limited and excess power. Based on estimated time constants, suitable heat-up time is calculated to minimise the time when temperatures stay below setpoint during occupancy. The energy saving potential of night-time and weekend setback periods in an office are analysed. It is found that the energy saving potential of setback is low under given constraints. Therefore, for modern buildings the cost-optimality has to be assessed separately for specific cases.

The reliable operation of Heat Recovery Ventilator (HRV) is critical for maintaining a healthy indoor environment to remove contaminants and moisture, however, it remains a challenge in the Northern Canada due to the frequent frosting under the extreme cold conditions. The heat generated by a building-integrated photovoltaic/thermal (BIPV/T) system can be used to pre-heat the incoming fresh air in HRV in order to reduce its defrost cycle, therefore, improving the reliability of HRV to provide adequate ventilation required. In this case, the BIPV/T needs to be designed for higher air temperature rise, which may not be optimum for the thermal energy and PV power generation. Therefore, system integration and optimization for coupling BIVP/T with HRVs is required. Depending on the level of thermal energy available and the outlet air temperature from the BIPV/T system, a control strategy needs to be developed to optimize the operation of HRVs. This paper presents the analysis of four different BIPV/T configurations and their integration with HRVs for a 120 m2 house located in Iqaluit, NU, Canada through modelling. Results show that the outlet air of a BIPV/T façade installation can be 14.8 °C higher than outdoor air on a clear sky winter day and that the defrost cycle can be reduced by 13%, up to 619 h annually.

The energy use for ventilation (heating and fan electricity) accounts for a large part of the energy use in residential buildings. For residential buildings, in many cases the building is occupied only part of the day, and further the pollution and moisture load generated by household activities varies during a day. Using demand controlled ventilation (DCV) has a great energy saving potential both regarding fan and heating energy. However, it is important how the ventilation is controlled in order to ensure an adequate indoor air quality, thermal comfort and avoid damages on the building. In this study different control strategies, control parameters, number of sensors and placing of sensors, number of zones are tested by modeling a single family house. Conclusions from the study are that the size of the energy saving depends on control strategy and system design and it is important to design and choose appropriate control strategy to obtain a good indoor environment.

According to the Energy Performance of Buildings Directive recast of 2010 all new buildings in European Union shall be nearly zero energy buildings from 2021 and onwards. However only very few of the countries in the Europan Union have to deal with very cold arctic climatic conditions, i.e. Sweden and Finland. Further, the required energy performance of a nearly zero energy building should be calculated on the basis of a methodology, which may be differentiated at national and regional level. This means that the definition may be quite different from member state to member state. This paper presents how different solutions regarding design of building envelopes combined with different heating and ventilation systems in single-family buildings can meet the energy requirements for nearly zero energy buildings. The main focus is on how the proposed Swedish building regulations for nearly zero energy buildings affects the possibility to build single-family buildings in the very north arctic part of Sweden. The main conclusions from this study is that the building envelopes in most cases need to be improved compared today existing standard and that direct electric heating will not be an option. Further, also with improved building envelopes solutions with extract air heat pumps will have difficulties in meeting the tougher energy requirements, especially in single-storey buildings. However geothermal heat pumps will meet the requirements even with existing building envelopes and even with only exhaust ventilation without heat recovery. Also air-water heat pumps combined with ventilation heat recovery can meet the requirement.

Green roofs are complex technology systems, adopting a vegetation layer on the outermost surface of the building shell. A proper design implement environmental and energy benefits. Green roof are aimed to reduce roof temperature and thus the summer solar gains, without worsening the winter energy performance. Most studies evaluating green roof performance have been conducted in warmer climates. There are very limited studies of green roofs in cold climate. Some research has investigated the thermal effect of the snow layer on green roof. But no study has so far evaluated the energy performance of green roof in sub-arctic climate. This study evaluates the heat flow and thermal effect on a green roof situated on a passive house building in the sub-arctic town Kiruna, Sweden for a period from 25th of October—4th of January. The ongoing measurements of temperature and heat flux is done on an extensive green roof and compared to the same roof covered solely by a roofing felt layer. The fluctuation in temperature was consistently higher for the roof with the roofing felt layer than for the green roof. But the surface temperature of both roofs was getting more and more align as the roofs are covered by snow during November and December. However during December month the green roof had a higher heat flux out of the building compared to the black roof.

As the operational energy use in buildings contributes highly to the total energy used and greenhouse gases emitted in the cold climate regions of Europe, buildings which are more energy-efficient and less carbon-intensive during operation are key to meet sustainability objectives in these regions. Yet, research shows that the practice of passive or low-energy buildings in the sub-arctic climate of northern Sweden is comparatively less than in the southern region. Moreover, previous studies did not explicitly examine the performance of low energy buildings in sub-arctic climate in relation to established building energy efficiency standards. Consequently, knowledge regarding the energy performance of low-energy buildings in such climate is limited. Therefore, the aim is to evaluate the performance, in terms of indoor temperature and energy use for heating, domestic hot water and electricity of a new-built passive house titled “Sjunde Huset” in the sub-arctic town of Kiruna. It is Sweden’s northernmost house designed to fulfil the Swedish passive-house criteria of a maximum heat loss factor of 17 W/m2 and a maximum annual energy use of 63 kWh/m2. The implemented passive design strategies include a highly insulated, compact and airtight building envelope with a vestibule, mechanical ventilation with heat recovery and renewable energy production through photovoltaic solar cells. The house is connected to district heating and is equipped with energy-efficient appliances to allow low occupant energy use. Ongoing performance evaluation is based on building simulation and measurements of energy and temperature in different zones of the building. Energy performance deviations between occupied and non-occupied zones are explored through internal heat gain evaluations. The indoor temperature is also evaluated to assess the temperature variations throughout the year. The ongoing research further evaluate a comparative simulated and measured energy analysis of heating, hot water and electricity based on both the international passive house standard and the Swedish passive house criteria “Feby 12”.

This paper studies the technical adaptability of energy-saving windows in green buildings based on thermal comfort and thermal defect for the severe cold climate region of northern China. Firstly, this paper makes statistics and analysis on the energy-saving window technology of green buildings in severe cold region. Secondly, this paper selects a representative public green building to tests its thermal comfort and thermodynamic disfigurement. The results show that the link between walls and window frames become weak links in technology. The large area of glass maintenance structure does not apply to the south side of the underground although it can save the lighting energy.

In 2013 a web-based questionnaire was sent out to residents living in apartments in multifamily housing areas with the aim to get their opinions on what renovation measures they prioritized and what they would be willing to pay in terms of percentage rent increase. On a neighbourhood level, the result showed that higher indoor standard followed by higher standard on the exterior façade and windows were on the top of the list followed by better light environment, parking spaces and waste rooms. On apartment level, the most important measures were renovation of kitchen and bathroom followed by a reduced noise from neighbours and increased thermal comfort. The willingness or ability to pay for these measures was however quite low. More than one third of the tenants could not accept any rent increase while nearly half of the residents could accept a rent increase of 1–10% and very few could accept rent increases above 10%. Considering the cost for implementing the desired measures, the rent increase would probably be considerably higher than 10%. This is why it is of crucial importance to have a close dialogue with residents at an early stage in the renovation process in order to find the most cost-efficient package of renovation measures that responds to the technical, environmental and social needs of the buildings and their residents.

The building sector has a key role to play in implementing the EU energy efficiency objectives. Around 40% of the energy consumption and a third of CO2 emissions comes from buildings. With the adoption of Nearly Zero Energy Buildings throughout the EU from 2020 onwards, these figures will be reduced in a perceptible and sustainable way [1]. To achieve such a significant reduction before 2030 with the current low new built rate, a comprehensive effort on upgrading existing buildings is necessary. Thus, we should aim for more optimized refurbishment solutions, in addition to building new and more energy efficient buildings. Upgrading existing buildings to higher energy standards is usually far more difficult than obtaining the same standards in new buildings. In many cases, upgrading to the nZEB-level [2] is unlikely to be cost effective. Thus, the Passive House Institute has published the international EnerPHit Standard for retrofit of existing buildings [3]. This article compares the Norwegian energy standards with the international EnerPHit Standard for retrofitting. The article also analyses the upgrade potential of a typical Norwegian wooden house from 1960 to 70 by following the EnerPHit Standard using the “step-by-step” method. Two different programs are used for energy simulation: The Passive House Planning Package and SIMIEN. Furthermore, the article briefly discusses how building automation can be used as a next step to increase energy efficiency. Upgrading of a typical Norwegian wooden house from 1960 to 70 is not free from challenges, but it is possible to achieve the EnerPHit Standard following the “step-by-step” method.

Adding exterior insulation as an energy saving renovation measure is not always possible for cultural heritage reasons. This study explores the energy saving that can be made if glazing instead is added to a heavy structure as a brick building creating a double skin façade. Extensive measurements have been made in a full-scale building. The building has then been modelled in IDA-ICE and simulations, validated by the measurements, have been made for both an outdoor climate representing the southern part of Sweden, Malmö and for one climate representing the northern part of Finland; Sodankylä. The annual heating energy savings have been calculated for various design combinations; different U-values and for both mechanical exhaust respectively mechanical supply and exhaust ventilation systems. The results show that an energy saving is achieved in the order of 8–38% depending on the design of the building; the glazing and the ventilation system. As both a southern and northern climate of Scandinavia are studied the results indicates how this type of renovation measure would perform in general in this part of the world.

The Swedish government aims to reduce total energy demand per heated building area by 50% until 2050. A large number of residential buildings, built within the so-called “Million homes program” in Sweden, need major renovations, which offers an opportunity to implement energy efficiency measures and thereby, reduce total energy demand. The best way to encourage the implementation of a major renovation is to demonstrate a practical method which reduces energy demand and provides economic benefits. Hence, this study aims to determine the most cost-effective energy solution in renovating a multi-family residential building. Multiple energy renovation measures were simulated on a case study to reduce the space heating and domestic hot water by 50%. The case study building was built within the “Million homes program” and is located in Växjö, Swedish climate zone 3. Design Builder software was used for analysing the pre-renovation energy performance of the building. The renovation measures comprised different insulation thicknesses of external walls, attic and ground floors, windows with different U-values, a mechanical ventilation with heat recovery system, and solar system for supporting space heating and domestic hot water. Later, a multi-objective optimization was accomplished for analysing every possible combination of renovation measures. The most cost-effective energy solution was obtained by calculating the net present value in a lifetime of 30 and 50 years and discount rate of 1, 3 and 5%. Comparing the implications of two different lifetimes on net present value with implications of three different discount rates on net present value shows that lifetime has more influence on net present value. Furthermore, the results show the capability of the multi-objective optimization method in analysing multiple renovation solution.

To achieve housing retrofit targets, traditional house-by-house approaches must scale. Neighbourhood retrofit also facilitates community participation. This paper aims to quantitatively characterise the heat energy demand of similar homes in a post-retrofit neighbourhood. The method employs the Modelica AixLib library, dedicated to building performance simulation. A modern semi-detached house is modelled as thermal network. The passive thermal network is calibrated against an equivalent EnergyPlus model. The developed Modelica model then generates time series heat energy demand to meet occupant comfort. This model separates heating for internal space and domestic hot water. Simulation results are gathered for a range of house occupancy profiles, with varying heating schedules and occupant quantities. The calibration results compare the time series of internal house temperature produced by the EnergyPlus and Modelica simulations. Modelica simulations of two heating schedules generate distinct annual demand curves against occupant quantity. As expected in a modern house, domestic hot water accounts for a relatively high proportion of heat energy. Over a year it ranges between 20 and 45% depending on occupant profile. Overall conclusions are threefold. Firstly, occupant profiles of a modern semi-detached house increase annual heat energy demand by 77%, and the coincidence of daily peak demand persists across occupant profiles. Furthermore, percentages of domestic hot water demand start from 20 or 24% and plateau at 39 or 45% depending on space heating schedule. A statistical distribution of energy demand by neighbourhood homes is possible. Its curve plot is not perfectly normal, skewing to larger energy demands.

A questionnaire survey investigates the conditions for future roof renovations, driving forces and incentives as well as barriers to install roof mounted or roof integrated photovoltaics (PV) among Swedish owners and managers of multi-residential buildings. Respondents were identified through a database hosted by the Swedish Energy Agency holding information about all projects that received subsidies for installation of PV between 2009 and 2016. The final sample comprised 77 organizations and the response rate was 36%. The questionnaire covers general information about the responding companies’ property portfolios; roof renovations in general; routines, motives, and driving forces for installation of roof PV; and planned roof renovations. Results show that the main cause for conducting roof renovations is end of life-time and improvement of energy efficiency. The initiative to install PV is mostly taken by the board of a Housing Association, the management team, or the board of a company. Standard PV modules mounted onto the roof is the predominant choice. Better profitability is needed to encourage more PV installations, for example, through higher subsidy levels and long-term security of the value of produced electricity. None of respondents asks for more appealing design of PV products, better internal organization, or improved knowledge about operation and management of the PV plant.

Energy saving is one of the driving forces in renovation of buildings. Ideally, energy savings should cover the cost of renovation. For purposes of cost efficiency, energy use before and after renovation should be known as accurately as possible. If the energy saving target is too ambitious, energy use after renovation could increase notably and, vice versa, if the target is too low, renovation may not be feasible. In this study we analyze how well the energy saving targets are achieved in renovated apartment buildings in Estonia. The analysis is based on measurements and simulations of indoor climate and energy use in 20 comprehensively renovated apartment buildings. A professional designer and consultant have made an energy audit and design solution before the renovation. Our task was to check the energy audit and compare target and real energy use. We found out that in most cases energy auditors have not assessed existing structures and ventilation correctly, and that basic energy audits should be more detailed in order to assess the existing buildings’ energy consumption. Energy saving targets after renovation were also overoptimistic. Based on our research the Estonian energy renovation grant scheme was upgraded.

This study applies an environmental return on investment approach to evaluate building refurbishment from a life cycle perspective. The used methodology focuses on the changes introduced by refurbishment, i.e. added embodied environmental impact and changed operational environmental impact, from a life cycle perspective with the technical service life of the refurbishment measure as a time limit. The methodology is applied to a case study in Umeå, located 455 km south of the Arctic Circle, with a unique set of data on reduction in operational energy. The result show the environmental impact, energy (Joule) and GWP (CO2-eq), in terms of environmental return on investment of the case study refurbishment measures. The case study shows that the methodology is a useable approach to compare refurbishment measures from a life cycle perspective. It is possible to use the methodology as a tool at an early stage in planning of sustainable building refurbishment from a life cycle perspective. For a widespread use of a tool based on an environmental return on investment approach, further research on guidelines for sustainable environmental return on investment values is required.

Considering the high share of residential buildings in the total energy use in Sweden, having the ambitious national energy and climate goals in mind, the real estate sector and its issues have been under a lot of attention during the past few decades. The Swedish real estate sector has often been identified with its ambitious public housing program during the record years (1960–1974). This was at the time the largest housing program per capita in the world where more than a million apartments were built in a nation with a population of 8 million. These apartments once being the pride of a nation, are facing a lot of problems today, ranging from vacancy and unacceptable physical condition to very poor energy performance. These buildings at the verge of their service/economic life are in need of extensive maintenance and renovation measures. Considering the technological development today, the problem with maintenance and renovation remains to be the financial constraints. These are what makes planning for maintenance and renovation complicated and cost inefficient. Although there are tools that can help property managers with maintenance and renovation planning, they all fail to address the complexity of the decision-making process in a multi-objective criteria under financial and time constraints. In this study, the focus is on the life cycle economy of the building components subject to energy performance improvements during renovation. A systematic approach has been proposed that can be used to budget and plan renovation with regard to energy efficiency under budget constraints. This approach utilizes a modified condition/deterioration model of the method Schroeder to simulate the maintenance effect on the condition state of building components in order to obtain the cost-optimal maintenance regime under given restrictions. This methodology can be used to compare the cost effectiveness of different energy-renovation scenarios and determine the optimal renovation plan for a single or a combination of buildings with regard to owners’ objectives and existing constraints. The results from this study illustrates how prioritizing action plans can affect the life cycle costs of building components.

The town of Kiruna, founded in 1900 in the northernmost part of Sweden, is nowadays in the middle of an impressive urban transformation: due to the impacts of mining activities a large part of the city center has to be moved or rebuilt. Among the buildings to be moved and kept in use are some of the so-called ‘Bläckhorn’ timber houses, designed by Gustaf Wickman in the early 20th century as residential units for the workers of the mining company LKAB and part of the original core of Kiruna. This has raised several questions on the sustainability of renovating historic buildings in a sub-arctic climate. In order to explore the challenge of increasing the energy efficiency of the Bläckhorn houses, data on their constructional and historical features as well as their thermal and energy performance have been collected. The paper addresses the following issues. Historic buildings are often blamed for their poor energy efficiency without considering their usually high constructional quality. What do we know about the real performances of these buildings? Energy retrofits in non-monumental and inhabited historic buildings are often guided by practical and operational needs rather than by their heritage significance. Can a value-based approach affect the improvement of energy efficiency? In a subarctic climate, even simple interventions can help to save a considerable amount of energy in historic buildings. To which extent the energy performances of the Bläckhorn houses could be increased without affecting their heritage values?

Swedish multi-family buildings constructed before 1945 constitute an important part of the national built heritage. However, the majority does not have a formal heritage protection. Part of this building stock has already been renovated, notably through earlier energy saving programmes where additional exterior insulation, new façades and windows were frequently installed with little consideration for the original architecture. Now, 40 years later, these buildings face new renovations. This provides opportunities to improve the energy efficiency, indoor climate and user comfort. At the same time, the original architectural and historical characters lost in previous renovations could be recreated. In this paper, an inter-disciplinary research team illustrates the challenges met in practice to reach a sustainable renovation based on three cases. The case buildings are so-called “Landshövdingehus”, constructed in the 1930s and owned by a public housing company. The relations between building physics, energy efficiency, embodied energy, and the effect on heritage aspects in renovation are studied. The results demonstrate the potential to reach 30% calculated energy efficiency without investing in ventilation systems. When comparing embodied energy to savings in operational energy a short payback time is achieved. However, focusing on the replacement of windows, the cases illustrate difficulties to recreate heritage values at same time as achieving an air-tight and energy efficient construction. In order to improve the results from the heritage point of view, there is a need for quality assurance of the renovation and building permit process.

High temperature district heating systems are connected to high losses, therefore, new district heating systems have lower temperatures. In Zero Emission Neighborhoods (ZEN) the heat demands are reduced and 4th generation district heating (4DH) solutions opens as a solution to provide the heating demands with lower transmission losses. However, district heating (DH) has to cover demands in new, renovated and old buildings connected to the supply. Therefore the supply temperature cannot be reduced without further consideration. One strategy to cover demands is to connect older buildings with higher temperature requirements on the supply pipe and the new/renovated buildings on the return pipe. A second strategy is to use local boosters (at building level), e.g. heat pumps or boilers, in a low temperature DH network, to supply the buildings that require high temperature supply (old radiators, leaky envelopes…). Either way, the fundamental constraint is what is the minimum heating supply temperature in different building types? In turn, this holistic approach will map the minimum DH supply temperatures that the heating demands of all the buildings forming the ZEN can be covered. This paper analyzes for the case study of residential buildings in Norway according to the archetypes defined in the Tabula/Episcope projects. The focus of this paper is on single-family houses of the seventies. Each case is subdivided based on energy performance (original, standard renovation and ambitious renovation). The buildings were simulated in IDA Indoor Climate and Energy (IDA ICE). The effect of renovation on the achievement of thermal comfort levels compared to minimum supply temperature is studied.

The QUB/e method is a dynamic measurement method developed to estimate the whole heat loss coefficient and local U-values of a building in a single night without occupancy. The ability of the method to provide reliable results was demonstrated experimentally in a climate chamber with controlled conditions in a previous work. This paper presents the findings from a series of in situ measurements carried out in a circa 1960s multi-family housing located in Stockholm area (Sweden). The U-values estimated with the QUB/e method were in good agreement with the quasi steady-state (ISO 9869-1) values (i.e., the relative differences were within the uncertainty bound of the measurement methods). It was thus demonstrated that the QUB/e method can deliver a good estimation of the thermal performance of building fabrics within just one night, significantly less than the 2–4 week period required for quasi steady-state methods.

There exists a building energy performance gap between theoretical simulations and the actual energy usage as measured. One potential reason for this gap might be a mismatch between predicted and measured values of the heat flux q through the building envelope. There is therefore a need to develop accurate and more cost-efficient methods for measurement of q. The standard ISO 9869-1 states that, at the outdoor surface, q = ho(Ts − Tenv), where ho is the overall heat transfer coefficient, including both convective and radiative components, Tenv is the environmental temperature, and Ts is the temperature of the building surface. It has previously been shown that the sol-air thermometer (SAT) could be used for convenient measurement of Tenv under dark conditions. In the present work, two SAT units, one heated and the other unheated, were employed for accurate outdoor measurements of ho in cold winter climate. Validation was performed by comparison of results from the new method against measurements, where previously established methodology was used. With current operating conditions, the measurement uncertainty was estimated to be 3.0 and 4.4%, for ho equal to 13 and 29 Wm−2K−1, respectively. The new SAT steady-state method is more cost-effective compared to previous methodology, in that the former involves fewer input quantities (surface emissivity and infrared radiation temperature are unnecessary) to be measured, while giving the same ho results, without any sacrifice in accuracy. SAT methodology thus enables measurement of both Tenv and ho, which characterizes the building thermal environment, and supports estimation of q.

Demand-Controlled Ventilation is emerging as a dominant ventilation strategy in non-residential buildings in Norway. The ventilation airflow rate is controlled between pre-set minimum (Vmin) and maximum (Vmax) values, based on the signal from room-sensors. The choice of Vmax is based on current knowledge about necessary airflow rate to reach an acceptable IAQ (indoor air quality) with maximum likely personal load and emission load from building materials. The choice of Vmin has an obvious impact on energy use, but there are few studies about its impact on IAQ. Vmin varies typically from 0.7 to above 2 (l/s)/m2 in Norway. In several buildings, Vmin is set to the upper range of this interval due to technical limitations of the specific equipment used. We have performed blind cross over intervention-studies with an untrained test panel to evaluate PAQ (perceived air quality) when entering 20 PAQ-rooms. All the rooms have low-emitting building materials, but extra pollution sources were introduced in some of the rooms for this study. Supplementary, intervention studies were performed in a dedicated test room to assess the impact of airflow rate on PAQ, performance and well-being during the first 20 min of occupation. We found that increasing Vmin has a significant positive impact on PAQ in rooms with extra pollution sources. This effect was not consistently present in the low-emitting rooms. Airflow rates did not noticeably affect PAQ, performance and well-being during the first 20 min of occupation. This indicates that Vmin above 1 (l/s)/m2 has limited benefit to IAQ in low emitting rooms.

In order to characterize and control a system properly, it is inevitably necessary to understand and define the interactions between various design parameters and the controllability of the system. This study experimentally investigates effects of three design parameters, including supply water temperature, fan speed, and room heat load, on the dynamic response of a fan coil system. The experiments have been performed in a mock-up of an office room equipped with a fan coil unit (FCU). A direct ground cooling system has been used to supply the FCU with high-temperature chilled water ranging between 15 and 23 °C. The dynamic response of the system to step changes in the design parameters has been studied using room operative temperature as an indicator. The results of this study indicate that the system behaves as a first-order system without a time delay. The results also suggest that the time constant and the characteristic of the dynamic response of the fan coil system are not affected by the initial room temperature. Among the design parameters, fan speed is observed to have the most significant effect on the dynamic response of the system. Supply water temperature and room heat load are both found to have insignificant effects on the dynamic response characteristics of the system.

In extreme cold climates, conventional single core heat/energy recovery ventilators experience major problems with ice formation on the extracted airside and frequently under-perform or fail. A dual core design could overcome the performance of single core design units and meet the rigorous requirement for operation in the North. The evaluation of the performance of a dual core unit was undertaken using dual environmental chambers capable of reproducing the typical outdoor and indoor conditions with regard to temperature and relative humidity. Experiments were conducted under a range of outdoor cold temperatures, and indoor conditions identified for housing in the Arctic. The dual core ERV was found to be capable of withstanding a temperature of down to −37 °C without deteriorating its thermal performance, and therefore was more frost-tolerant than conventional single core units. In conclusion, the dual core design system could be a feasible option for extreme cold climates.

In cold climates, the defrost strategies of the dominant conventional single core heat/energy recovery ventilators (HRVs/ERVs) involve the recirculation of exhausted (return) warm air across the heat exchanger core and back into the supply air for the house. In harsh cold climates, this type of defrost strategy can undermine ventilation performance. A dual core ERV design could overcome this issue by providing continuous ventilation. It has a potential to perform better than a conventional single core unit and meet the rigorous requirements for operation in the Canada’s North. This paper provides an experimental comparison of the efficiency between single and dual core ERVs using the twin houses at the Canadian Centre for Housing Technology (CCHT) as a test bed. The side-by-side testing also provided valuable data to measure the impact of the installation of a dual core ERV in a real residential application. Both houses were operated identically and monitored for a range of winter weather conditions. Changes in test house performance due to the innovative dual core design were observed and compared to the performance of the reference house. The parameters that were compared include: efficiency, airflow, indoor temperature and relative humidity, and energy consumption. This paper discusses the effectiveness of the dual core design ERV, energy use of the house and the ventilation rate.

Application of ground source heat pumps (GSHPs) in extreme cold climates can be challenging due to the long heating season even with heat pumps designed and marketed for colder climates. One challenge (of several) is design of the ground heat exchanger under conditions where the desired minimum heat pump entering fluid temperature (EFT) is close to the undisturbed ground temperature (UGT). Furthermore, ground heat exchanger (GHE) models used for design purposes and/or energy calculation purposes don’t usually incorporate freezing and thawing of the soil. This is the case whether the freezing/thawing is induced by surface conditions or by heat transfer between the ground heat exchanger and the surrounding soil. A recently developed model (Xing and Spitler in Sci Technol Built Environ 23(5), 809–825, 2017, [1]) implemented in a simulation-based ground heat exchanger design tool (Oklahoma State University in GLHEPro 5.0 for Windows—Users’ Guide. Stillwater, 2016, [2]) incorporates the effect of surface-condition-induced freezing/thawing when calculating a 2nd-order harmonic approximation for the undisturbed ground temperature. This paper examines the suitability of this harmonic model in GHE design applications by comparing the predicted GHE design to the actual design of a GHE at the Cold Climate Housing Research Center (CCHRC) in Fairbanks, Alaska. Field measurements of UGT and GHE performance are used to examine the limitations of the harmonic model.

The solar-assisted heat pump devices have attracted ample attention as potential alternatives to the conventional technologies for domestic hot water production. Precise COP estimation of the hybrid system is a prerequisite prior to conducting any effort to design and install as well as a necessity for market support and optimal system assurance. Here, to develop a model along that has a high precision and reliability, but less complexity and computational time, the ability of soft computing approaches for predicting the performance of a solar-assisted heat pump system for domestic hot water production is reported. The experimental data gathered from a real project in China and different intelligent models are developed based on the measurements. First, owing to the complexity of our studied system and the high number of influential parameters, a novel and unique multi-objective optimization technique based on NSGA-II optimization method is proposed to determine a set of optimum variables with the highest influence on the desired output. Based on the Pareto frontier, seven input variables out of forty eight are considered for the desired output. The reliability of the developed models is evaluated via statistical and graphical error analyses. It was inferred that integration of the MLP-ANN with the suggested variable selectin algorithm outperformed the other methods by introducing an R2 = 0.9951 and RMSE = 0.0917. The current investigation can aid as a gear in the direction of improving the precision in estimation of performance of solar-assisted heat pump devices.

In the future, most buildings will be nearly Zero Energy Buildings (nZEBs). Heat pumps are frequently used as heating system in Swedish single family buildings, but in most cases they are used in buildings with higher heating demand than the nZEBs of tomorrow. In this study, operation parameters such as heating water and brine temperatures were analyzed in real operation in two different nZEBs. The results show that the measured supply temperatures coincide in some cases well with what is described in the standard developed to be harmonized with the ecodesign and energy labelling regulations—EN14825, but in some cases they were higher. However, the brine temperatures were often considerably higher than the test conditions described in EN14825. The results also show how interconnection of a tank affects the operating parameters of a heat pump system. Another finding was that in order to reach the highest overall energy performance the heat pump and the heating system must be optimized together and not separately, which often is the case today.

Conventional air-source heat pumps (ASHPs) experience rather poor performance in cold climate areas. The heating capacity and efficiency of conventional ASHPs decrease significantly as the outdoor temperature decreases. The major R&D challenges are to limit this ASHP heating capacity and efficiency degradation at low and extremely low ambient temperatures. Vapor injection (VI) compressors are able to provide better efficiency and larger capacity at low ambient temperatures. A prototype air-source cold climate heat pump (CCHP), using tandem vapor injection (VI) compressors and inter-stage flash tank, was developed. The CCHP has two identical VI compressors in parallel, which works with a two-stage indoor blower and two-stage thermostat. At moderately low ambient temperatures, only one compressor is called, and at extremely low ambient temperatures, both the compressors are used. The prototype was installed in Fairbanks, Alaska and underwent field testing for six months. The CCHP successfully operated down to −30 °F (−35 °C) and was able to meet the building heating load with good efficiency in a wide range of ambient temperatures. At −30 °F (−35 °C), the CCHP delivered 75% heat pump capacity, relative to the capacity at 47 °F (8.3 °C), and the heat pump COP was 1.8. This paper will introduce the CCHP development and field testing results.

Enabled by the advancement and incorporation of inverter-driven compressors and controls, cold climate air source heat pumps (CC-ASHP) are being introduced in the Canadian marketplace. Such systems are capable of efficiently meeting space heating loads at much colder ambient temperatures in comparison to single speed compressor air source heat pump (ASHP) technologies and are additionally capable of efficiently modulating to meet heating loads at warmer ambient temperatures without cycling on/off. Coupled with their lower capital costs than ground source heat pump systems, significant interest in these systems has been generated; however their widespread adoption is hindered by the unknown performance and lack of tools to evaluate their energy saving potential. This paper presents the results of detailed performance tests measuring the heating output and power input of two types of CC-ASHPs popular in the Canadian residential marketplace; a centrally ducted 3 ton split ASHP designed for whole house heating and cooling and a 1 ton ductless split ASHP designed for displacing zone heating and cooling requirements. The tests are completed by varying the outdoor temperature and indoor load (or compressor speed/capacity depending on the test approach) in climate controlled test facilities. The test results validate the systems’ capability of efficiently heating at low ambient temperatures as well as modulating to meet more moderate part load conditions. However, several factors including the operating mode of the system as well as built-in protection controls for discharge temperature and pressure can serve to limit the maximum available heating capacity. Defrost settings can have a substantial impact on total system performance at cold temperatures. At mild ambient temperatures, relatively small heating load requirements can result in short cycling. The results highlight the importance of properly sizing and commissioning these heat pump systems for their application and indicate the type of data required to better simulate the performance and properly evaluate their energy saving potential.

Ice rinks have a simultaneous cooling and heating demand to maintain the ice slab and providing the required heat to different needs in the ice rink facility. This provides a potential for utilising a heat recovery function, which is used in many ice rinks with traditional ammonia (R717) systems, however using carbon dioxide (R744) as a refrigerant in a trans-critical system can provide a fully self-sufficient ice rink in terms of heat. In R744 systems more heat is available at higher temperature levels, whereas in R717 systems the largest heat portion is present at condensing temperature level, which does not fulfill high temperature heating demand. In this study energy saving potential with heat recovery systems in ice rinks is evaluated. A system solution is developed, modelled and evaluated. One objective is to look at using R744 as refrigerant in ice rinks, however, focusing on the heat recovery aspect. In order to check the applicability, a R744 system with heat recovery is compared to traditional R717 refrigeration system with a propane (R290) heat pump. Data from an ice rink in operation is used to map the heating demand during season and to increase credibility. The results show that heat recovery performance in ice rink with R744 direct refrigeration system uses 47 MWh less energy than in indirect R717 systems with R290 heat pump, which constitute to 16%.

The increased use of electric vehicles (EVs) calls for new and innovative solutions for charging infrastructure. At the same time, it is desirable to improve the energy flexibility of neighbourhoods. This paper presents state-of-the-art for smart EV charging systems, with focus on Norway. Norway is a leading market for EVs, with more than 110,000 EVs and 2000 charging stations. The paper describes how charging stations can interact with the energy need in buildings and neighbourhoods, local energy production and local electric and thermal energy storage. Examples of commercial smart EV charging systems are described. Smart EV charging systems have the potential to improve energy flexibility in a Zero Emission Neighbourhood (ZEN). Such EV charging systems can also interact with heating loads in neighbourhoods. Piloting of new technologies and solutions can provide more knowledge about smart EV charging systems, and how they can participate in matching energy loads in buildings and infrastructure with local electricity generation and energy storage.

A renewable method to mitigate the slippery condition on road surfaces is to use Hydronic Heating Pavement (HHP) system. The HHP system starts heating the road when the surface temperature is below both of the dew-point and the water freezing temperatures. Furthermore, in order to improve the anti-icing performance of the HHP system, it is necessary to pre-heat the road surface. The aims of this study are to evaluate the effects of: (i) pre-heating the road surface and (ii) varying the fluid temperature, when the road is pre-heated, on the anti-icing performance of the HHP system. The road surface was pre-heated by adding a temperature threshold (from 0 to 1.6 °C) to the freezing and dew-point temperatures. A two-dimensional numerical simulation model was developed using finite element method in order to calculate the annual required energy and remaining hours of the slippery conditions on the road surface. The numerical solver was validated by an analytical solution associated with an infinite region bounded internally by a pipe with a constant temperature. In order to evaluate the anti-icing performance of the HHP system, the climate data were selected from Östersund, an area in middle of Sweden with cold and long winter period. The results showed that running the HHP system by considering the temperature threshold of 0.1 °C for both freezing and dew-point temperatures led to approximately 110 h shorter slippery conditions on the road surface, compared to the conditions without pre-heating.

Residential construction and land use planning are changing in many countries around the world. There is a clear need for comprehensive, energy-efficient, cost-effective and CO2-neutral concepts meeting the latest energy and climate policy goals. This opens up new opportunities for the industry. Northern Finland has strong expertise in the field of wooden architecture and wood construction industry. By combining the existing high-tech expertise of enterprises, and strengthening the cooperation between SMEs, new value networks with significant international business potential can be created. This paper presents the Life City-concept, a holistic approach for smart and sustainable built environment, which is being created in the ongoing Life City-project. The concept consists of energy-efficient and modern wooden buildings in CO2-neutral neighborhoods and includes decentralized energy infrastructure with multiple renewable energy sources and smart networks. Life City-concept is a comprehensive export concept that adapts to the local climate conditions, but also considers the social needs of different communities. Other targets of the Life City-project include enhancing the export business knowledge and technical prerequisites of the collaborating SME companies. In cooperation with the companies, the project aims to develop new design, manufacturing and construction methods that enable improving the cost-effectiveness, environmental impact, energy-economy, microclimate and other living comfort issues of wooden buildings in different climate zones, taking also the climate change and resiliency issues into account. Preliminary project results show that the wood construction industry in Finland is not quite ready for exporting holistic concepts such as the Life City-concept, as more product development, knowledge and resources for export are needed. This finding applies especially to SME companies in the industry.

Due to stricter building energy requirements, future buildings will be characterized with low base loads and occasional high peaks. However, future building areas will still contain existing and historical buildings with high energy use. Additionally, there is a requirement that future building areas have to get energy from renewable energy sources, while existing buildings need to make transition to the renewables. The aim was to analyze different energy systems and technologies that can help to reduce CO2 emissions in the future building areas in Norway. In this study, different methods were combined: detailed building simulation, energy supply technology simulation, heat demand aggregation, and data post-processing. The results showed that the energy pathways would be very dependent on the CO2-factors for the energy sources and it is hard to tell which CO2-factor is correct. An increasing housing stock development would slightly increase the CO2 emission towards 2050, even though the new buildings used half the energy than the existing buildings and the existing buildings undergone energy efficiency improvements. A constant housing stock would decrease the CO2 emission by around 22–27% depending on energy supply systems. The results showed that the influence of implementing stricter building codes had a lower impact on the total CO2 emissions, compared to the influence of the CO2-factors and energy supply technologies. Regarding the existing buildings, the requirements such as: limited use of direct electric heating, requirements on the service systems, and definition on hot tap water use should be emphasized.

Several concerns about energy have been discussed during recent decades, such as the shortage of traditional energy resource, increase of energy price and destruction of the living environment. To solve these problems, sustainable development of energy become a preferential task all around the world. Under current circumstances, applying energy saving measures and using renewable energy resource are two of the best choices. The goal of this study is to assess the potential of applying energy saving measures and adding renewable energy resource for the campus of Lund University in Sweden. Energy consumption simulations towards representative buildings were performed for both current and future climatic conditions, meanwhile, investigating the potential of adding solar and wind energy. For energy saving perspective, results show that adding insulation material to old walls, adjusting heating and cooling set points, applying high-efficient heat recovery system, and adding shading devices would have significant effects. Effects of future climatic conditions on heating and cooling energy consumption are considerable. From adding renewable energy resources perspective, results show that the campus of Lund University have enough potential to applying solar and wind energy resources by installing PV systems and small-scale wind turbines. Besides, future climatic condition would not have huge or certain influence on renewable energy applications.

Dynamical model identification is an essential element in the implementation of a model predictive controller. In this work, a control-oriented first order model was identified in a dedicated experiment on a super-insulated single-family house. First, parameters resulting from CTSM and the MATLAB System Identification toolbox were compared. Then, a comparison of model predictions and measurements showed that this simple model captures well the main dynamics of the building-averaged indoor temperature, after one week of training on rich data with sample time below 15 min. It was also observed that this prediction performance was not affected by the configuration of internal doors.

Since the antique the Vitruvian virtues three basic qualities, solid, useful and beautiful is central themes when judging architecture. Although the themes have remained, the conceptual idea of these qualities has shifted. In today’s modern society, sustainability requirements are an integrated perspective, often expressed as a balanced consideration of ecology, economy and social aspects. There are numerous approaches to measure and evaluate sustainability. Often the perspective of the evaluator’s model is predominant. An alternative approach is to ask architects or designers to describe the sustainable idea. This is an approach used to identify alternative perspectives. In this work, we introduce a multiple case study. The scope, to investigate sustainable architecture based on the architects or designers own drawings. The aim is not to define sustainability in architecture but rather to illustrate articulated examples of integration of sustainability issues in architecture. The study is limited to a selection of 22 buildings, proposed as exceptionally sustainable in public media. The northern subarctic and artic regions here are the geographical boundary. The cold climate description used as the background for illustrating a variety of sustainable concepts. We propose that descriptive information, interpreted from the architect or designer perspective, has important contributive factors in the understanding of sustainable housing. We argue that the architect or designers design critique influences the result of conceptual meaning. The attention given to sustainability is the founding architectural factor in these studied buildings, expressed in various forms.

The global climate agenda has challenged the construction sector and led to a significant use of technology in buildings. At the same time, new technologies like Internet of Things, Big Data and Artificial Intelligence are beginning to fit into the buildings’ technical systems. Knowledge is available about the technical side of the “intelligent building” however, there is insufficient practical experience and knowledge about the competencies that are required in order to interact with the intelligent building. The purpose of this analysis is to elucidate competence requirements in connection with the dissemination of building automation in large buildings. The study is based on qualitative interviews of six industry organizations and four organizations that in different ways relate to the operation of large buildings. They are strategically chosen whereas they represent four different models of building operation. In the study, building automation is related to the construction sector’s need for finding optimal solutions and methods that ensure knowledge transfer across building operations and construction projects. The results indicate that (1) building operation can be configured in many ways, (2) the different building operation models work towards optimization of operation using building automation (3) the different building operation models use different strategies for transferring knowledge from operation to building project. The recommendation is that a forward-looking competence strategy can benefit from building on a system understanding of building automation, rather than a sole focus on technical specialization. The analysis also points to the need to explore building automation as a socio-technical system, thereby supplementing the technical research of the past.

The regulation “Obligatory Ventilation Control, OVK” has been into practice since 1991 in Sweden. The role of the regulation is to control the ventilation in premises, multi-family houses and single and two-family houses (with certain ventilation systems). The control is done before the ventilation system is taken in operation and after that on regular intervals (except for single and two-family houses). The purpose of the OVK is to secure that the indoor climate is good and that the ventilation system is functioning. This paper will present results on how the OVK works today, both in theory and in practice and, by stakeholders, identified wished development of the OVK. To get a broad picture of how the OVK works, interviews were carried out with persons related to the OVK; building owners, OVK controllers, administrators at the municipality, legislators, organizations etc. Based on this, suggestions were made for how the OVK could develop to better suit its purpose. Results from the interviews show that an approved OVK is not a guarantee that the indoor environment is satisfactory, since the current use of the premises isn’t taken into account. Further, the legislation for ventilation is not adapted to new technology such as demand control ventilation, and different authorities’ legislation also differs regarding for example reduced/shut off ventilation. The study also shows that the follow up of the OVK from the municipality often are inadequate. Further, energy-saving measures that should be included in the OVK are handled very differently and the level varies considerably.

A vertical temperature stratification normally exists in rooms during the heating season in cold climates. An expression of the gradient in apartments heated by hydronic radiator heating systems with exhaust ventilation has earlier been developed assuming a dependency of the outdoor temperature. The expression was used by a public real estate owner when re-calculating measured indoor temperature at 2.1 m above floor to 1.2 m above floor representing the occupancy zone and used for individual metering and billing of space heating cost. To validate the suggested expression temperature measurements have been made at four heights in living rooms in apartments built in the 70’s. The heights includes 0.0, 0.1, 1.1 and 1.7 m above floor. The theoretical expression has been compared to the full-scale measurements and in general the expression overestimates the vertical temperature gradient. The measured gradients are generally very low. The thermal comfort in the aspect of vertical temperature gradient is good for the studied period.

There is a major need of cost-effective renovation that leads to lower energy consumption and better environment. This article shows the results from a pilot case of a newly developed prefabricated building system. It is an industrially prefabricated insulated wooden element adapted to renovation and upgrading of building envelopes. The renovated building is a one-story office building located in Skellefteå in the north of Sweden. Energy performance, thermal bridges, risk of moisture problems, LCA, applicability of the renovation method and assembly time were evaluated during the planning and execution of the renovation. Results from this case show that the elements were very light and easy for one person to handle at the building site. There is a great potential to reduce assembly time with improved joints and element sizes adapted to the building as well as improved batch packaging from the factory. With 100 mm insulation, the renovation gives a certain energy savings, and LCA calculations show that the reduction of climate impact due to reduced heating energy used during a service life 50 years corresponds to the climate impact of the renovation measures. The risk of microbial growth can be regarded as small.

Mold- and moisture problems have damaged and prevented the use of many buildings in Finland; typically, the problems have existed in school buildings, but also in other public buildings like health centers and day care buildings. Even relatively young buildings have had those problems. The reasons are caused roughly by three factors: design errors and deficiencies during construction and use. The learning environment has deteriorated. Both pupils and teachers have had various symptoms, in some cases they have been unable to use the building anymore. The situation has led mostly to a continuous repair cycle—the indoor environment and conditions have not always reached the satisfactory level. In this presentation, firstly, the reasons and solutions for indoor air problems in different cities are introduced, and then is described, how the service life of two school buildings has been extended. The existing problems are described and what measures are needed to carry out that the indoor environment would reach a safe and healthy level. In both cases the recent condition and situation are analyzed, and then reported some realized renovation works based on monitoring and measurements, which are briefly described. After modifications and repairs the buildings have been monitored during 2 years. The aim was to keep both buildings in use during a limited time period. The use of the other school building was discontinued and the other school will change the use. In both cases the community authorities decided to try to extend the service life instead of a new school building. Massive and deep renovation operations were excluded because of the high costs; there should be a way to find how to have more time for planning and financing new schools without using temporary spaces or substitute premises. The other building was overpressurized after repairs, which is not normally used; in other building targeted repairs were done. In this presentation, the research and monitoring program, starting point, renovation measures and monitoring results are presented. Special attention has been paid to ventilation systems and also to the typical reasons for indoor problems—very often one cannot name just one factor, but the performance is depending on more than one factor. The performance of a building depends on how well the building systems are integrated to operate together—envelope, heating, ventilation and automation systems—and also performance depends on the use, users and weather conditions.

Net Zero Energy Buildings constitute one measure to reduce energy use and increase use of energy from renewable sources. Hence, it is important share knowledge and experiences from completed projects. This case study show that it is possible to build Net Zero Energy Buildings with existing techniques. However, a common strategy to prevent or limit the build-up of ice and frost in ventilation heat exchangers, Supply fan shut off, were not suitable this project, since it is air tight buildings. After occurring problems in the first winter, ventilation pre-heater were installed to prevent the build-up of ice and frost. Thanks to placement of temperature sensor after the pre-heater, the increased energy use for pre-heater may be expected to be low, roughly 1 kWh/m2a.

Thermal bridges influence the thermal standard of a building envelope. They are taken into account in the linear thermal transmittance or Ψ-value, and can be estimated from tabulated values for standard building details or from numerical modelling. However, these methods are not applicable for existing buildings with unknown structure. In these cases, in situ measurement of the Ψ-value is necessary. In this study, a methodology to measure the actual thermal bridging performance is developed. The methodology is based on a infrared thermography technique, which can be used on any existing thermal bridge. To ensure high accuracy, temperature-dependent surface heat transfer coefficients are calculated using the surface temperatures recorded by the infrared camera. The methodology has been validated under steady state conditions in a hot box apparatus with very good agreement.

Thermal mass has the benefit of regulating energy in buildings and generates potential savings in energy and CO2 emissions. Window and local shading can provide shelter and reduce the severity of overheating during the year and mostly during the summer period. The aim of this study was firstly to evaluate the influence of window shading to reduce overheating and secondly to assess the thermal mass benefits in the presence of shading devices to alleviate the impact of overheating. This study was based on dynamic thermal simulations to analyse the performance of different window and local shading devices to avoid overheating. Twenty building simulation models were performed using the Energyplus plugin in DesignBuilder to evaluate the effect on the thermal mass behaviour to mitigate overheating according to different window shading devices. This study confirmed, as expected, that the use of window shading helps to alleviate the overheating hours in the test room and as such, improving the thermal comfort and reducing the need for cooling. Furthermore, when the window shading devices are coupling with thermal mass and night ventilation, the reduction on overheating hours achieved will reach a reduction of over 50% with respect to not exposing the thermal mass. In conclusion, exposing the thermal mass coupled with a night ventilation strategy provides a reduction on overheating hours, which is increased by using different window shading devices. Exposure of the thermal mass provides a good strategy for reducing the need for cooling and increasing thermal comfort.

Swedish building regulations require proof that a building fulfills a specific energy use during the design stage. This is done by doing an energy calculation. The result of this calculation is always reported to the nearest integer, for example an energy calculation of a building might predict that it should use 89 kWh/m2 year when the building regulation limits the actual energy use to maximum 90 kWh/m2 year. This can lead to conflicts if the measured energy use is greater than the calculated energy use. With the currently available energy calculation tools, if you want to see which risks are associated to the design and material properties, you need to do a parametric study. These types of studies are usually time consuming. Investigations of different buildings show that energy measurements can vary significantly in identical houses. To take into account these differences and avoid costly parametric studies, it is common to add an uncertainty factor to the calculated results. In the project, “Calculation method for probabilistic energy use in buildings” two commercial energy calculation programs developed in Sweden were modified to use Monte Carlo simulations. This method was then tested using a passive house design which was used in the Vallda Heberg passive house development. The calculation results were then compared with the actual measured energy. The results show that a variation of 15 input parameters could explain most of the difference between measured energy use and calculated energy use. The results from the probabilistic energy calculation even showed that the original energy calculation was on the high-end of the calculated energy distribution. It showed that the probability that the measured energy use would fulfil the Swedish building code was over 95%.

Using wood stoves is a common space-heating strategy in the Nordic countries. Currently, the lowest available nominal power of wood stoves is significantly oversized compared to the design space-heating load of highly-insulated houses. This oversizing might deteriorate the indoor thermal environment by causing overheating and a large vertical temperature stratification. Modelling the indoor thermal environment of rooms heated with a wood stove with acceptable computational time and accuracy, however, is a complex task. The purpose of this study is to analyze the accuracy of a new IDA-ICE zonal model currently under development and to calibrate it against measurements. For this, several experiments were conducted in a test cell, which was heated by an electric stove mimicking a wood stove with a nominal power of 4 kW. Room air temperatures in various positions were measured, while the stove that was placed in the middle of the room was run in cycles with different durations and surface temperature profiles, leading to a thermal stratification of 0.5–2.2 K/m. The zonal model could reproduce the temperatures at the bottom and top layers of the room with good accuracy. However, the model still needs further development and validation to reach good agreement with measurements in the middle layers of the zone. Nevertheless, already at this stage, the model could be used to roughly assess thermal stratification in rooms heated by wood stoves.

TEKNOsim is a simple and user-friendly program for analyzing thermal indoor climate and performing annual hourly simulations. The program was originally developed to calculate heating and cooling demands, and indoor climate conditions of a single zone building for peak winter and summer design days. However, TEKNOsim version 6 has been revised to incorporate several new features including annual energy and multi-zone simulations. These features greatly enhance the functionality and the ability of the program. Their implementation in TEKNOsim 6, however, entails a validation procedure to test the accuracy of the new algorithms. This paper presents preliminary results of the ongoing testing and validation of TEKNOsim 6 according to CIBSE TM33 tests for software accreditation and verification. The test results indicate that the new database libraries implemented in TEKNOsim 6 can be easily customized to precisely represent the actual building conditions. The results also show that the program can accurately calculate the total steady-state heat losses for all test cases of CIBSE TM33. The peak cooling loads calculated by TEKNOsim 6 are also in good agreement with CIBSE TM33 for most test cases. Some discrepancies are however observed between TEKNOsim 6 and CIBSE TM33, especially for test cases involving certain building elements. Nevertheless, TEKNOsim 6 is shown to be a fast and reliable program for performing early-design stage simulations.

The presented study describes developing a method for observing building occupants’ activity. Once their activity is registered, such data can be used to identify typical patterns in their behaviour. The collected information will support development of an occupant-behaviour-energy-related model in residential buildings. Data registration was done with the use of the Microsoft Kinect device as a depth registration camera. This research explores an innovative approach to investigating residents’ living and working habits. It supports the already existing thermal comfort models by delivering high resolution information about occupants’ activities. The obtained solution and its output will be used in the next stage of developing a dynamic metabolic rate (D-MET) model that will simulate the MET value. With proper data, it will be possible to estimate the real impact of occupants and their behaviour on energy consumption of buildings.

Here, we explore key input parameters and common assumptions for energy balance analysis of residential buildings in Sweden and assess their impacts on simulated energy demand of a building. Our analysis is based on dynamic hour-by-hour energy balance modelling of a typical Swedish multi-storey residential building constructed in 1972. The simulation input parameters studied are related to microclimate, building envelope, occupancy behaviour, ventilation, electric and persons heat gains. The results show that assumed indoor temperature set points, internal heat gains and efficiency of ventilation heat recovery systems have significant impact on the simulated energy demand. For microclimate parameters, the outdoor temperature, ground solar reflection and window shading gave significant variations in the simulated space heating and cooling demands. We found that input parameter values and assumptions used for building energy simulation vary significantly in the Swedish context, giving considerably different estimated annual final energy demands for the analysed building. Overall, the estimated annual final space heating demand of the building varied between 50 and 125 kWh/m2 depending on the simulation dataset used. This study suggests that site-specific parameter values may be appropriate for accurate analysis of a building’s energy performance to reduce data input uncertainties, as such factors may have a significant impact on building energy balance and energy savings of retrofit measures.

Different building energy modelling programs exist and are widely used to calculate energy balance of building in the context of energy renovation of existing buildings or in the design of energy performance of new buildings. The different tools have unique benefits and drawbacks for different conditions. In this study, four different types of building energy system modelling tools including TRNSYS, Energy Plus, IDA-Indoor Climate Energy (IDA-ICE) and VIP-Energy are used to calculate the energy balance of a recently built six-storey apartment building in Växjö, Sweden. The building is designed based on the current Swedish building code. The main outcomes of the software include hourly heating and cooling demands and indoor temperature profiles. We explore the general capabilities of the software and compare the results between them. For the studied building with similar input conditions such as weather climate data file, infiltration and ventilation ratio and internal heat gain, IDA-ICE modeled the highest space heating demand while the TRNSYS the lowest due to the simplification of thermal bridges. The main advance feature of VIP-Energy is the detail thermal bridge analysis while the main drawback is the complexity of using the model. EnergyPlus and TRNSYS can be used for energy supply system integration with the ability to add mathematical sub-modules to the models.

Energy efficiency aware building owners are facing a massive amount of different retrofitting options. However, a quantitative assessment of the different options requires a high level of technical expertise. In this contribution, a fast and novel simulation platform for the assessment of different residential heating system configurations is presented. This platform enables dynamic simulations of the complete heating system, calculating energy/heat consumption and comfort indicators for different heating systems during a full year in less than 5 s on a recent laptop. Another key feature of the platform is the inclusion of a large variety of different heat sources (oil/gas/biomass/carbon boilers, air/brine-water or sorption heat pumps), sensible thermal heat storages, as well as building models. Shortly, this system will be the core of a platform enabling interested users to calculate the energy consumption of different retrofitting options accurately. To validate the system models, the energy consumption of the three reference buildings (single family houses with an annual heating energy demand of 15, 45 and 100 kWh/m2) as per the IEA SHC Task 44 is calculated and compared with reference simulations from established simulation frameworks. The energy consumption of these buildings matches the reference values up to 5% for a full year simulation requiring calculations times between 3.3 and 3.7 s on a recent laptop.

A detailed multi-zone building model of an existing zero emission residential building (ZEB) has been created using the software IDA Indoor Climate and Energy (IDA ICE). The model will later be used for investigating control strategies for the heating system to activate the building energy flexibility. The main purpose of this paper is to show how reliable the model reproduces the short-term thermal dynamics and the temperature zoning of the building. This is of particular interest for the control of heating, ventilation and air conditioning (HVAC) systems in order to provide meaningful insights of active demand response (ADR) measures. The model has been validated using data sets from seven experiments. Two dimensionless indicators, the normalized mean bias error (NMBE) and the coefficient of variation of the root mean square error (CVRMSE) were applied in order to evaluate the trend of the average indoor temperatures. The first approach considered standard operating conditions, where the measured indoor air temperature was used as input for the control of the electrical radiator and the total electricity use of the radiator as an output. Excitation sequences have been used in the second approach, where the electric power of the radiator has been imposed and the operative temperature taken as the output. The model shows good agreement between the temperature profiles from the measurements and the simulations based on the NMBE and CVRMSE remaining below 5% for most cases.

Airing can be a solution to introduce extra ventilation in large single zone buildings, especially where there are large aggregations of people such as churches or atriums. In naturally ventilated domestic and ancient buildings, opening of a window or door can introduce extra fresh air and remove particles and other contaminants emitted from people and other sources such as lit candles in churches. However, the energy use might be an issue in cold climates, where airing might lead to waste of heated air, at the same time as indoor air temperatures can be uncomfortably low. In the present study, the energy loss and ventilation rate due to airing in a large single zone (church) building is investigated via IDA-ICE simulation on annual basis in cold weather conditions. The results can be used in order to prepare airing guidelines for large single zone buildings such as atriums, churches, industry halls and large sport halls. According to the results, one-hour of airing in the studied church building resulted in 40–50% of exchanged room air and, if practiced once a week, an increase of around 1% in heating energy.

In order to calculate building energy usage, apart from the technical characteristics, user related factors needs to be determined. Unless the user related factors are determined by specific project, the idea is to apply a standardized list of input data for a normal operation during a normal year, so the calculated energy value does not depend on variation of these factors. Such list was issued by Boverket (The Swedish National Board of Housing, Building and Planning) in a document named BEN1 in 2016, and updated in BEN2 in 2017. A disadvantage of this list is that, the part about schools is based on references that are rather older and sparse and needs to be updated. This paper investigates the user related input data in 10 newly built low energy schools in Sweden and compares those to BEN2. It also compares the schools’ calculated energy performance to the BBR25 requirement, the latest national building codes and recommendations. The schools are investigated in this research as there is a demand for about 1000 elementary schools to be built in Sweden in the coming 10 years. The paper shows significant user related effect to energy usage and importance for the standardized user related input data for energy calculations. Future research aims to verify these calculations and user related input data with measured data for the chosen schools.

This paper investigates the conceptual framework and impacts of business models in model predictive control (MPC)-based geothermal Thermally Active Building System (Geo-TABS). The analysis is done by compiling technical, political, economic, social and environmental analytical frameworks of MPC Geo-TABS. The elements of the business model Canvas are identified and analyzed in this application. Theoretical bases of business model generation are verified by substantiating arguments and potential profit analysis for stakeholders via four demonstration buildings. The focused building types/cases involve office building, schools, elder-care houses and multi-family house. Methods to verify the proposed value propositions in the business model are given special interests. The results show that correctly sizing and combining the four major components: MPC, geothermal, TABS and suitable building types, are the core in both technical and business development perspectives. Complete design guidelines are crucial for promoting MPC Geo-TABS business in its service chains. Transforming the conventional economy-oriented business development method to holistic sustainability-oriented profit matrix can further strength the value propositions of MPC Geo-TABS. The findings aim at supporting decision-makers and further improving engineering guidelines in implementing MPC based Geo-TABS in a larger scale in Europe.

The design concept of conditioned atria receive growing popularity in both commercial and service buildings all over the world, but still not common in the residential sector. This study used a psychological framework to examine if building design with enclosed heated atria in apartment buildings can enhance sense of community and social interactions in Nordic climates. A qualitative study was conducted to understand the perception of residents living in apartment buildings with heated atrium. One of the few examples in Sweden. This was compared to the experience of residents in a “traditional” apartment building without an atrium. The questionnaire was comprised of six parts: (i) socio-demographic aspects; (ii) information about the apartment; (iii) social activities within the building; (iv) social interaction with neighbours; (v) information about principles in life; and (vi) sense of community linked to their homes. The results showed significant social differences between the residents of the atrium and “traditional” buildings, which could not be explained solely by differences in preferences and principles in life. A large proportion of the social differences between the buildings could be explained by the building design, as the common and semi-private areas within the atrium building provide opportunities to establish social interactions. The residents in the atrium building was found to have greater sense of community and higher frequency of interactions, which are both parts of social sustainability.

The successful implementation of energy efficiency measures in the residential sector will depend to a large extent on the attitudes and perceptions of the end-users since they are the final decision maker. The tenure of the housing could influence the building occupants’ perspectives on energy issues. In this study we conducted a comparative evaluation of perspectives on energy use of three categories of households: those living in single family houses, tenants and owners’ of apartment. The analysis is based on responses to a mail-in questionnaire by approximately 650 residents in Umeå, Sweden. Majority of the respondents believed that their annual household energy use is less. Residents in single-family houses, as compared to the other two types of tenure of the housing, were more likely to believe their heat energy use as high and likely to take actions to reduce the energy use. Financial incentives such as subsidy or lower interest rate were preferred by most of single-family homeowners (45%) to motivate them to take actions to reduce energy use. While personalized information to reduce energy use and lower interest rate and reduced rent are preferred by more residents in the other two categories. The implications for promoting energy efficient measures based on housing tenure is discussed.

Energy efficiency measures in residential buildings typically include changes in ventilation and heating systems, and increased thermal insulation of the building envelope. The expected energy efficiency is not always reached, despite large knowledge and professional implementation of each separate measure. There is a lack in understanding of how technical systems interact, and how the occupants are influenced by and in turn influence the systems by their behaviour. A holistic view and a transdisciplinary research approach are needed to understand relevant interactions and propose integrated energy efficiency measures. The aim of this paper is to reveal challenges in transdisciplinary research projects that include real world studies on both humans and technical systems with measurements before and after renovation of multifamily housing. It is based on experiences from the PEIRE-project (People, Environment, Indoor, Renovation, Energy) carried out by a research team with expertise on environmental psychology, human behaviour, interaction design, universal design, building physics, building services, thermal comfort, aerosol technology, exposure assessment, acoustics, daylight, and complex thinking. Differences in theoretical bases and methodology needed to be dealt with. Metatheory building could help with the transition from a multi- to a transdisciplinary understanding.

Indoor air quality affects human health. These effects can be either positive of negative. Straw bale building has been claimed as a sustainable way of building. The aim of this study was to evaluate indoor air quality in two of Estonian straw bale houses and provide solution of monitoring for indoor air quality and hygrothermal conditions of boarders as complex. Samples were collected between October 2014 til March 2015. Sampling media and procedure was designed according to ISO standard 16000-18: Detection and enumeration of moulds—Sampling by impaction. Data loggers for collecting the data about CO2, temperature and humidity were also used. Two of them (recorded temperature and humidity) were installed inside the wall (depth ~20 cm), the third logger was used as a desktop logger. We also collected some straw samples inside the wall to see which kind of microorganisms are living on them. Samples were plated, total colony forming units were counted and identified from the isolated colonies. The results from air samples (CFU) were in one house higher than in the other one. Temperature, humidity and CO2 levels were also higher in one house. This is probably affected by the different building characteristics (one of the houses is modular wall straw bale house, the other one is timber frame straw bale house). Species, which we found, were similar in both houses. The most fungal genes isolated from samples were Aspergillus, Penicillium, Alternaria and Cladosporium.

There has been a lot of research over recent years on children’s thermal comfort, which highlighted the different needs of young children compared to adults. These findings pose a challenge to designers on how to best meet these needs. This paper focuses on recommended temperature zones and assumptions used in standards through a case study in a grade school in Gothenburg, Sweden. Six classrooms were investigated in three buildings of the same school. The indoor temperature was measured using small-scale data loggers programmed to log at 5-minute intervals for a period of 5 months (mid-December to early-June). Thermal comfort questionnaires were also distributed to children throughout the monitoring period. A total of 45,000 temperature readings corresponding to assumed occupied hours and approximately 2000 thermal sensation votes and clothing insulation values are used in the analysis. Results indicate that assumed occupancy schedules may differ to real use, leading to overestimation of time when indoor environmental parameters are outside recommended ranges. Children’s clothing insulation was found to be lower than assumed in standards in both winter and summer. Omitting to account for such differences may lead to misinterpretation of indoor environment assessments and design solutions.

Everyday thermal environments affect people’s comfort and wellbeing, with extreme conditions affecting human health. A strong focus on avoiding the extremes along with the introduction of tight thermal comfort criteria over the years has led to design strategies and behaviors that promote thermally stable indoor environments. However, recent research has shown that indoor temperature variation has significant health benefits, e.g. it could help tackle diabetes and obesity. These findings suggest that it is important to investigate not just the average temperature levels in households but also their distribution and variation over different periods. In Sweden, indoor temperatures are considered to be on average high and constant due to a combination of the heating provision mechanism and the high building standards compared to other countries. This paper investigates the temperature distributions in Swedish households using detailed 15-minute indoor air temperature measurements from the 2008 BETSI-survey, provided by the Swedish National Board of Housing, Building and Planning (Boverket). Approximately two million measurements from 1306 households taken during two-week periods in winter 2007/08 are used in this investigation. Indoor temperature variation is investigated in two levels: (i) over the 2-week monitoring period and (ii) within-day. Results showed a considerable range in average dwelling temperatures of 9 K, highlighting a substantial variability between homes in heating temperature and most likely in thermal comfort preferences. Regardless the different temperature levels, the majority of dwellings maintain stable thermal conditions, as demonstrated from the very low temperature variations found. Differences in daily temperature patterns were also observed.

Use of massive wood has increased during the last decade. The concept of massive wood, mainly as cross laminated timber elements (CLT), has become a popular building method for new constructions, both in public and private sector. Massive wood elements take advantage of wood as building material, also as an indoor climate buffer. Moholt 50|50 is a new student-housing project in Trondheim, Norway, which consists of five mass timber towers. Each of them with eight stories built in CLT on top of a concrete storey. Apart from the student homes, the buildings host facilities, such as activity center, kindergarten, commercial areas and a library, also built in CLT. This makes Moholt 50|50 a significant wooden living lab in Trondheim. The building technique follows the development from the first Norwegian CLT student housing built in Ås in 2012, and reproduced later on in similar patterns in other Norwegian cities, as Tromsø, Haugesund, Drammen, Fredrikstad, Halden, Hønefoss, Porsgrunn and Trondheim. Research on comfort and operation cost coupled to indoor surfaces are included in project Moholt 50|50. The towers are built according to Norwegian low energy standards. All surfaces are treated with water solvent varnish, apart from two stories in one of the Moholt timber towers. Four stories are instrumented to document the difference in the behavior of untreated and treated wooden surfaces. Measurements show a different indoor climate of the stories with untreated surfaces. The measurements presented give preliminary results of a measurement period which, when finished, will include one year of inhabited studios from the date of moving in.

Black carbon (BC, soot, elemental carbon) is a component of airborne particulate matter, which has been linked with negative effects on respiratory and cardiovascular systems. BC is considered an indicator of combustion related component of particulate matter, which can be emitted from both outdoor and indoor sources. Pollution control measures focus mainly on outdoor concentrations, whereas control of indoor levels seem to be neglected despite the fact that we spend on average 90% of our time in indoor environments. The aim of this study was to assess the differences in BC concentrations inside and outside occupied residences during weeklong real time measurements in ten residences. BC concentrations were measured simultaneously indoors and outside of ten occupied residences using two microAeth® AE51 (AethLabs, USA) instruments. Continues measurements inside and outside lasted at least seven consecutive days in each residence. Comparisons of BC concentrations were conducted for the times when occupants were present at home and when there was no one in the residence. Average concentrations of BC during occupancy time were comparable between indoors and outdoors. However, a significant contribution of indoor sources to measured BC was observed. High concentrations of BC indoors were due to cooking and candle burning. Concentrations of BC during non-occupancy time were higher outdoors than indoors as expected, as there were no indoor activities which may have contributed to observed levels indoors. Obtained results indicate that in order to minimize exposure of occupants to BC concentrations, efficient control measures of indoor emissions might be as important as prevention of outdoor pollution infiltration to indoor environments.

The aim of our study is to investigate whether it is necessary to adjust the ventilation requirements according to different user groups. This study is focusing especially on teenagers, who might have a higher odour load than children due to increased hormone and sweat production during puberty. The odour intensity (OI) and the perceived air quality (PAQ) were evaluated in four classrooms in Oslo, Norway. Two control classrooms of 9–11 years olds (children) were compared with two case classrooms of 12–15 years olds (teenagers). A sensory panel of 18 untrained people visited the four classrooms three times during a three-hour period and were asked to evaluate PAQ and OI upon entering the classrooms. The classrooms were supplied with a constant ventilation rate of 7 l/s per person, with no additional ventilation for building materials. We found that the classroom with children had a significant better PAQ-score than both classrooms with teenagers. Furthermore, although the ventilation rate per person was reduced, the percentage of panellists dissatisfied with OI and PAQ was lower (<20%) than expected. Our results indicate that children and teenagers have different sensory pollution loads, and therefore might need differentiated ventilation rates if the ventilation rates were to be optimised. However, more research is needed.

Many Japanese people are dissatisfied with the coldness of dressing rooms and bathrooms. It is well known that accidents due to changes in blood pressure during bathing may lead to casualties, particularly in elderly people. However, measurements of blood pressure changes along with evaluation of the thermal environment in residential buildings are very limited. This study aimed to survey the influence that the thermal renovation of the dressing rooms and bathrooms has on the health of elderly residents during winter in residential buildings in Hokkaido, a cold northern region in Japan. Three detached residences built before the 1990s, whose residents were over 60 years of age, were renovated. Bath units were replaced, or additional thermal insulation was added to the openings and floor of the dressing rooms and bathrooms. Before and after the renovation, the thermal environment around the bathroom was evaluated and the blood pressure of residents during bathing was measured. From undressing in the dressing room until dressing after bathing, blood pressure was measured sequentially by the residents themselves using a handy-type hemadynamometer. After renovation, the increase in the highest systolic blood pressure during undressing time and the range of the blood pressure change during the whole bathing process were lower than those before renovation. Systolic blood pressure decreased with the increase in dressing room temperature. Correlation analysis showed that systolic blood pressure decreased up to 20 mmHg when the dressing room temperature increased by 10 °C.

This study aims to assess the effects of using wood stoves on indoor air quality (IAQ) regarding fine PM, ultrafine PM, CO2 and relative humidity in Norwegian residential houses. Measurements were performed in an old natural ventilated house and a new mechanical ventilated house. Three locations for PM measurements were selected: close to the stove opening, in the middle of the room and at the supply air inlet, with original installed stoves typical for the buildings’ time of construction. Each measurement lasted 3 h, which includes monitoring of the background concentration, the light up process, the burning and the refill processes. The results show peaks of fine and ultrafine PM emissions during the light up and refill phases, connected to opening of the wood stove door. The ultrafine PM peaks were higher and occurred more frequently than the fine PM ones, indicating that not only the opening of the wood stove door caused these PM peaks. Significant differences were found between the two houses regarding the relative distribution between fine PM and ultrafine PM. Peak concentrations of ultrafine PM took longer time to fall back towards background levels compared to the fine PM concentrations. No clear correlations were found between the load of the stove and PM emissions, and further research is required to assess why. Yet the situation was not alarming as the 24 h mean PM2.5 concentration in both houses was below the WHO guideline. CO2 emissions in both houses were on average always at a healthy level.

To assess how people are influenced by relative humidity (RH) in cold climates, a study was conducted in an open office landscape in Oslo, Norway. The study took place during three cold days in February 2017. Fourteen subjects were blindly exposed to different levels of RH in the order of low (14 ± 1%), high (38 ± 3%), and medium (24 ± 4%). The subjects received emails twice a day (at 12:00 and at 14:30) with a link to a webpage where they were asked to: (1) assess perceived air quality (PAQ), (2) respond to a questionnaire about indoor environment quality and symptoms. The subjects performed normal office activity in between the two sessions. We found no significant impact of the level of RH on PAQ. Nevertheless, there were significantly more complaints about dry air at low RH than at medium and high RH. Furthermore, the air was perceived to be significantly more stuffy and heavier at high RH than at medium RH. There were no significant differences in thermal comfort at different RH, yet more people complained that it was cold on the day with low RH and warm on the day with high RH. Generally, there were few complaints related to symptoms at different RH. There were however significantly more complaints of itching and burning in the eyes at low RH than at medium and high RH.

This study was conducted to assess how different filter types in the ventilation system affect the indoor NO2 concentrations. Measurements were carried out in two classrooms and air intakes in a primary school located in Oslo, Norway. A regular F7 particle filter and an F7 combination filter with activated charcoal lining were compared. NO2 concentrations were measured for five weeks during winter 2017 in a cross-over study design to compare: (1) NO2-levels in classrooms with regular filter (RF) versus combination filter (CF); (2) indoor/outdoor ratio with regular filter versus combination filter. One-hour average concentrations are reported during operating time of the ventilation system (6:00–23:00) and during hours with high (>40 µg/m3) outdoor NO2 concentrations. The measured average NO2 concentrations in both classrooms with an RF were significantly higher than with a CF. The median CF/RF ratios for the two classrooms were 0.50 and 0.81 during hours with high NO2 concentrations, and 0.48 and 1.00 during the period the ventilation system was operational. During hours with high NO2 concentrations, the median indoor/outdoor ratios for the two classrooms with an RF were above 1.00, while the corresponding ratios with a CF were 0.78 and 0.75. Our results demonstrate that a combination filter is more efficient than a regular filter in reducing NO2 concentrations in classrooms during hours with high outdoor concentrations.

Engineering methods of determining the position of the maximum moisture zone in enclosing structures have been theoretically justified. Calculation formulas have been determined with the use of moisture potential. This method has been used for studying positions of the maximum moisture zones in a enclosing structure wall made of aerated concrete blocks, with facade composite thermal insulation, external plaster with various layer thicknesses. It has been calculated that with the thermal insulation thickness over 37 cm the maximum moisture zone is located in the internal layer of the aerated concrete blockwork. The phenomenon has been called “the over-insulation effect”.

The use of timber structures in tall buildings increases the demand of moisture safety in facades. Moisture in the facade could result in unwanted consequences such as mold, decay and distortions in wood materials. This might have impact on the indoor climate and the building quality. The aim of this study was to evaluate the moisture safety regarding the composition of the façade and connection details such as windows and balconies. Scenarios with possible damages were evaluated with LCC (Life Cycle Cost) and LCA (Life Cycle Assessment). The scenarios were developed based on experiences from manufacturers and insurance companies and on research investigations of damages. LCC and LCA includes replacement of damaged building materials, transports of new materials and damaged materials for recycling or energy recovery and the use of energy for drying of moisture in the structure. Both light frame structures and CLT (Cross Laminated Timber) structures were included. Improvements of detail connections to increase moisture safety were also evaluated regarding risk of damage, costs and environmental impact. The results show that even small and inexpensive improvements will increase the moisture safety and significantly reduce the risk of damage.

Eight different clay-sand plaster mixtures were studied. Mineral content and particle size distribution were estimated for all specimens. Hygroscopic sorption properties were determined (in climate chamber) at temperature of 23 ± 0.5 °C. The specimens were weighed at 1, 2, 3, 6, 12, 24 h until stabilisation at RH level of 30, 50 and 80% Moisture uptake (kg/m2) and moisture uptake rate kg/(m2h); moisture content and; points at sorption curve were monitored. There were large differences in sorption properties depending on clay type and plaster recipes. Total uptake of moisture at 30, 50 and 80% of RH for 2.5 cm plaster was 9.4–301.1, 17.5–465.9 and 41.6–744.9 g/m2 accordingly. Standard (EN 1015-19) procedure was followed. Water vapour diffusion equivalent air layer thickness Sd = 0.08–0.12 m was declared. Strong positive correlation was found between the amount of calcite and sorption properties of plasters.

The test house with special timber structure was built by the department of rural building of Estonian University of Life Sciences. The hygrothermal properties of sawdust and cellulose, used as insulation materials in building envelope, were investigated in long term. The test was carried out during four winters. The wind and moisture-vapor barriers were not applied in the first testing period. In the second testing period the wall was covered inside with the moisture barrier and outside with the wind barrier and the layer of OSB plates. In wintertime the test house was heated with electric batteries to keep the indoors temperature stable. The aim of this research was to measure and determine the thermal transmittance of differently insulated wall sections. To fulfil the task the devices to measure relative moisture and temperature were placed in five different positions (in three depths inside the insulation) and indoors and outdoors. The heat flux plates were applied on the inner surface of the wall. Data were recorded with 10 min interval. The analysis of these test periods was carried out and presented in this paper.

It is a well-known fact that the built environment in Europe is responsible for approximately 40% of the overall energy end usage and that this has to be reduced drastically for the building stock to be sustainable in the long term. A prerequisite to meet the EU 2020 and 2030 targets is significantly increased ambition among property owners regarding energy-efficient renovation. However, it is not easy to regulate that large-scale energy-efficiency measures should be included in the ordinary renovation of buildings. In order to design the right policy instruments to influence property owners towards energy-efficiency-oriented renovation, deeper knowledge is needed on how property owners act and argue today. This study reviews several recently performed studies with the aim of obtaining an overview of how the decision-making process is conducted, and it makes comparisons between different categories of buildings. The aim is to allow conclusions to be drawn on whether a financial incentive is important to bringing about energy-efficiency renovation and, if so, how such an incentive should be formulated. The study shows that direct and simple subsidies are needed to bring about major energy-efficiency improvements in housing in connection with renovations, especially when it comes to additional insulation for facades. For non-residential property, there is little need for financial support, while other forms of support are needed. Current energy-efficiency improvements in connection with renovations are modest and a long way off the technical potential.

To continue to be an effective guidance tool for the property and construction sectors and to meet the environmental quality objectives, the Swedish certification system Miljöbyggnad needed to be developed. Over the years, new research results have been published and political decisions made that affect sustainable building and construction. What was rated as ‘best available technology’ ten years ago has now become standard. In this project, industry and academia have collaborated to implement research findings into practice. Miljöbyggnad considers requirements of energy, indoor environment and material use. The criteria give high scores for low heating power need, low heating loads from the sun, energy efficiency, high share of renewable energy, good sound levels, low radon exposure, good ventilation performance, moisture safety, indoor comfort in winter and summer, good daylight, low risk of legionella, documentation on material used, avoidance of hazardous substances and evaluation of the framework’s life cycle effects on climate change. Compliance with the criteria in Miljöbyggnad improves the potential for sustainable building design. The criteria give special consideration to fitting in with the outdoor climate throughout Sweden as well as Swedish building regulations and practice in the property and construction sectors. The work to evaluate and improve the criteria in Miljöbyggnad has taken two years and involved over 250 people from research and industry. The criteria are based on scientific values and can be verified, and they all support meeting different environmental objectives.

Normalisation of measured energy use in buildings is important in order to verify their performance in user phase. Two methods for normalisation have been presented in Sweden, static and dynamic normalisation. The static normalisation considers deviating hot water use, indoor temperature, internal loads and external climate. The dynamic normalisation is based on repeated simulation, meaning that the initial simulation, carried out during the design phase, is repeated with updated conditions regarding actual use of the building and exterior climate. The ratio between the first and second simulation is used as a factor for normalisation. A pre-study has been initiated in Sweden to enable further development of the two methods. This paper present the two methods, the initiated pre-study, and some early findings. The early findings show that there is need for further development of the methods presented.

Existing classification systems linked to the environmental performance of buildings provide limited added value for practitioners. A survey among Swedish construction entrepreneurs showed that there is a real demand for better formulated criteria and clearer guidance. At the same time, critical investigation of requirements based on fixed average values for primary energy factors (such as in the EU Environmental Performance of Buildings Directive) shows that they are insufficient to provide guidance towards environmental sustainability building practices. They fail to take into account a number of methodological issues, including seasonal and hourly variability of energy supply and demand, and the future evolution of energy mixes. This is illustrated in the case of Sweden. The outline of an Open Classification System, currently under development, is then presented. This system focuses on methodological transparency and validity, as well as ease of use for practitioners. It addresses specifically issues where other existing systems were found to be lacking, and its methodology will be assessed to ensure that it provides optimal guidance towards environmentally sustainable practices. The system is based on three criteria: the energy resource index and global warming potential, calculated with attributional and consequential life cycle approaches, and a heat loss factor to assess the building’s energy performance independently from the supply side.

The paper describes a statistical analysis of a mathematical model for calculation of the melting and freezing of snow on roofs. Parameters are roof length, overhang length, heat resistance of roof and overhang, outdoor and indoor temperature, snow thickness and thermal conductivity. If the snow thickness is above a limit value, then part of the snow will melt. This gives water flow to the overhang. Part of the water will freeze on the overhang and a part will drip from the roof. If the water flow is small, then all the water will freeze on the overhang otherwise there will be dripping and icicles. The paper uses sensitivity analysis with the Morris method to find parameters that are negligible, linear or non-linear. The Sobol sensitivity indices are also calculated. By means of sensitivity analysis, it is possible to determine, which parameters are the most important e.g. the thickness of the snow or indoor and outdoor temperatures and roof thermal resistance. In practice, some parameters are difficult to change, but the analysis shows where the effect is most efficient.

In 1997, in accordance with the UN framework Convention on climate change (UNFCCC) the Kyoto Protocol was adopted. In the Committee on adaptation (2012) States the need for all countries participating in the UNFCCC to develop national plans and programs for adaptation to conduct a technical study of the process of adaptation in different spheres and primarily in energy-intensive industries such as construction and operation of residential and administrative buildings. Based on the numerical solution of the differential equation that determining one-dimensional heat transfer under nonsteady conditions with constant coefficients, the method of calculation of the temperature distribution over the cross section of the enclosing structure was developed. On the basis of the developed method of determining the number of cycles of freezing and thawing of moisture in the cross sections of the outer wall of the building are calculated. The developed method was tested in the experiment on the exterior walls of operated buildings. The results showed good convergence of the real and calculated temperature values. The calculation of the number of cycles of freezing and thawing on the cross section of the outer wall of the building according to the developed methodology and the experiment showed the same results. The method of numerical assessment of the impact of global climate change on the enclosing structures was developed. The concept of temperature intensity of the year was introduce. The method uses meteorological data of outdoor air temperature for the previous period and the results of calculation of temperature regime of the enclosing structures. The use of this method allowed to calculate the number of cycles of freezing and thawing in cross sections of the outer wall at any time interval, and, therefore, more accurately predict the durability of the enclosing structures.

The Canadian North is experiencing several building engineering problems which must be addressed now to avoid worsening problems in the future. The permafrost layer is retreating downward in the Canadian North. This is resulting in many unstable homes in the 14 villages of Quebec’s Nunavik. Current tripod adjustable footings, while the most popular, are not the way of the future. Several other methods such as concrete footings on bedrock, or on deep permafrost, exist. When bedrock is very deep, steel piles represent a good way to stabilize buildings. Some cases require add freeze piles when bedrock is too deep to reach economically. Lattice truss systems on tripod footings have also been used. This report explores the most prominent solutions of the future and reinforces which methods are believed to best perform going forward.

The recent Norwegian passive house legislation has raised concerns as to whether the building industry was able to build cost-efficient buildings, without overspending tax payers’ money and having negative consequences for peripheral areas in particular in the very north part of the country. This paper aims at exploring and analyzing how these challenges created by the new legislation has been met during building of a new hospital block in Tromsø, the A-wing. Building on sustainable transition theory which identifies several recombinant dynamics, both public and private, we define the building of passive houses as a societal development encompassing dynamics like company development, personnel competences, as well as architectural, engineering and production methods. The empirical material draws on interviews, analysis of documents relative to the project and public media material. The case study revealed a mixture of recurrent, and specific cold climate challenges: some are directly related to passive house technologies, such as issues with the façade, others indirectly, such as Tromsø being a remote market for material and labour. The project encountered delays, shift in contracts and cost augmentations. Competences had to be developed and combined to achieve the standards of passive house building and the local workforce was complemented by adding workers from other regions and markets; the south and middle Norwegian, Nordic, Baltic and East European countries. Accordingly, the project was not isolated in the northern part of Norway and its challenges appeared to be rather organizational and managerial than technical.

A small Swedish architectural firm performs a strategy to internationalize in Sweden, Denmark and Norway, even into the most northern parts, Lofoten and Svalbard. These countries and areas exhibit similarities and differences, providing opportunity and barriers for architectural businesses to expand. Three strands of literature are used, business of architectural firm, internationalization, and strategy. The empirical material from the Swedish architectural firm, is gathered through semi-structured interviews and desktop research. The findings indicate that, when the firm executes its business outside local boundaries, three dimensions of strategy must be performed: (1) firm’s services are required by international clients. (2) Opportunity has to be provided and firm must response with flexibility. (3) The service, finally, is executed through an international project where synergy and customization are performed. The strategizing should inseparably relate to the multifaceted situation.

Recent years have seen considerable advancements in Demand Controlled Ventilation (DCV) systems aimed to improved energy efficiency and indoor environmental quality in buildings. A significant aspect of DCV systems is their impact on the acoustic comfort in buildings. This study is part of the Urban Tranquility project with a focus on innovative DCV systems. The objective is to add more understanding about communicating the acoustic performance of innovative HVAC solutions during the diffusion phase of the innovation. The research method is a case study on an innovative DCV system that shows how the acoustic performance of the system is communicated with the stakeholders and in what ways the applied methods can be improved. Data collection has been performed through reviewing relevant technical documents and software as well as semi-structured interviews with different stakeholders. The data has been analyzed with reference to three types of knowledge about an innovation. The results indicate that the acoustic performance of this new DCV system has not been effectively communicated due to inconsistent methods of expressing the information. This has revealed the need for developing a systematic method of communicating the acoustic information on DCV systems with the key stakeholders.