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Über dieses Buch

This book includes the most recent outcomes from research and professional practice in the ventilative cooling field, gathered by the selected panel of authors. It provides essential contents to face and reduce the rise of space cooling and ventilation energy uses in buildings by alternative ventilation and cooling solutions. The book is organised into three parts which include a detailed description of ventilative cooling boundaries and implications (working principles, KPIs, standards, comfort models, control techniques) and of principal techniques (night ventilation, controlled natural ventilation, hybrid solutions, PCM and mass activation, evaporative cooling, earth-to-air heat exchangers) along with an updated analysis of the background to the topic. Furthermore, the last part of the book defines a unique practical and theoretical framework to include ventilative cooling solutions in different building typologies along with their principal implications.



Chapter 1. Innovations in Ventilative Cooling: An Introduction

This chapter introduces the book’s contents and its structure. It also includes a short description of why Ventilative Cooling (VC) is increasing in importance in a scenario where building cooling needs are growing. The building sector is responsible for about 40% of primary energy consumption; space heating, cooling and ventilation have proved to be the main consumers. Even though great efforts have been made to reduce energy needs for space heating, much less has been done for space cooling and ventilation. However, this situation is bound to change given that energy consumption for cooling is expected to supersede that for heating between 2050 and 2100. The main features of this growth are analysed in consideration of the international style of buildings, the growth in comfort expectations and changes in comfort culture, the growth in internal heat gains, increasing air temperature and urban heat island, as well as the side effects of the advancement in building envelope optimisation to reduce winter consumption (solar gains, airtightness). In order to face these new developments, which are linked with local increases in air temperature due to the thermal by-product of conditioners and related Green House Gas emissions, natural and hybrid solutions are needed. This book focuses on Ventilative Cooling techniques which aim to be a complete and reliable reference for designers and engineers who are working in the field of environmental design and renewable energy in the building sector. In this book Ventilative Cooling boundaries including all relevant information, background issues, techniques and applications are discussed based on the work of an internationally recognised group of experts. This chapter contains a short description of the contents of each part of the book.
Giacomo Chiesa, Maria Kolokotroni, Per Heiselberg



Chapter 2. Ventilative Cooling Principles, Potential and Barriers

This chapter introduces the main principles of ventilative cooling and the key performance indicators (KPI) to evaluate performance. It also presents and discusses the application potential and limitations as well as includes a critical discussion of barriers to ventilative cooling usage. The chapter is based on the outcome of the international research Annex 62—Ventilative Cooling developed under the Energy in Buildings and Communities (EBC) Programme of the International Energy Agency (IEA).
Per Heiselberg

Chapter 3. Ventilative Cooling and Comfort Models

This chapter focuses on the description of comfort models for Ventilative Cooling. In particular, the adaptive comfort approach is described in full practical detail with an eye to related standards and regulations and designing buildings which will allow occupants to make themselves comfortable.
Fergus Nicol

Chapter 4. Ventilative Cooling in Standards, Legislation and Compliance Tools

The use of VC is strongly related to standards, regulations and national compliance tools. The chapter describes the current status and future recommendations for better implementation of ventilative cooling in standards, legislation and compliance tools. The content of the chapter is based on the extensive review of EN standards, ISO standards and national standards, as well as national legislation and national compliance tools. Information is also obtained through questionnaires answered by experts from 11 countries, all of which participated in the IEA EBC Annex 62. Study reveals that ventilative cooling is not well-integrated in standards, legislation and compliance tools. It also reveals that there is a broad field of evaluation methods for ventilative cooling, ranging from very simple to detailed, which can support a better integration of ventilative cooling in the near future.First in this chapter is presented status in: standards, legislation and compliance tools. Respectively the status is followed with recommendation on each.Chapter finishes with conclusions.
Christoffer Plesner, Michal Pomianowski

Chapter 5. Ventilative Cooling and Air Pollutants

The majority of office and other non‑domestic buildings use mechanical cooling and ventilation, even when an optimized natural ventilation (NV) system could meet cooling and fresh air requirements. However, in most large cities, the outdoor environment is contaminated with a combination of noise, fine particles, heat and toxic gases. This contaminated environment has a detrimental impact on naturally ventilated buildings due to their lack of filtration and outdoor noise attenuation systems. This chapter presents a numerical analysis of the effect of fine particle pollution (PM2.5) on the NV potential of office buildings in California, Europe and Asia. Several years of measured weather and PM2.5 concentration data were used to perform dynamic thermal and airflow simulation analysis. Detailed simulation results show that a hybrid NV system can reduce the air‑conditioning and ventilation electricity consumption of a well‑designed office building by up to 83% (which can be increased to up to 93% by the availability of personal comfort systems), in comparison to an office using, during all working hours, a mechanical cooling and ventilation system equipped with a high‑efficiency particle filter. Unfortunately, in this hybrid approach, high levels of outdoor PM2.5 penetrate the indoor environment, increasing occupant cumulative exposure by up to six times. To overcome this problem, two exposure control approaches were tested. Using NV only during moments of low outdoor PM2.5 concentrations limits the exposure increase to up to three times but at the cost of reducing energy savings. Equipping NV openings with an electrostatic filter would result in a similar exposure reduction, but at a very low energy cost, taking full advantage of NV’s saving potential.
Guilherme Carrilho da Graça, Nuno R. Martins

Chapter 6. Ventilative Cooling and Control Systems

Robust control systems are essential to guarantee an efficient usage of ventilative cooling. The most important challenges of controlling natural ventilative cooling are the outdoor environmental conditions like wind, rain, noise and pollen; security and interaction with and satisfaction of the user. The main control strategies and components of natural ventilative cooling, including actuators and sensors are described. From case studies, the following lessons are learned. The main driver for control of natural ventilative cooling systems is thermal comfort and outdoor weather conditions. Optimization and commissioning of ventilative cooling control is critical to maximize the cooling potential as well as to prevent overcooling. Conclusions on the interaction of the user with the ventilation cooling control are twofold. On the one hand, automatic control is preferred to manual control of ventilative cooling. On the other hand, the user should be able to overrule this automatic control. Suggestions for design are formulated. The users and their expectations of controllability play a central role. Moreover, the future maintenance of the actuators have to be taken into account in the design phase.
Hilde Breesch, Bart Merema



Chapter 7. Ventilative Cooling in Combination with Passive Cooling: Thermal Masses and Phase-Change Materials (PCM)

This chapter first describes the relation between the potential of ventilative cooling to reduce building cooling loads and the role of thermal storage to achieve this; thermal storage could be sensible in the form of exposed thermal mass embedded in the structure of the building or latent in the form of phase change materials embedded in the structure or decoupled from the structure but coupled with the ventilation system. The principles of how thermal storage contributes to passive cooling are described with examples from materialised case-studies. The chapter includes results related to the use of phase change materials in combination with ventilative cooling from an operational system.
Maria Kolokotroni, Thiago Santos

Chapter 8. Ventilative Cooling in Combination with Other Natural Cooling Solutions: Direct Evaporative Cooling—DEC

This chapter analyses the potential combination of ventilative cooling solutions with direct evaporative cooling (DEC) systems. The focus is on passive downdraught evaporative cooling (PDEC) towers, whose performance is described based on the analysis of monitored results. The main design aspects of PDEC towers are explained, including basic relationships and support tools for system optimization. A series of case studies is reported, illustrating different integration strategies and providing a series of examples for designers. Finally, a simulation-based approach to analysing the local potential of PDEC to reduce thermal discomfort in naturally ventilated buildings is introduced, providing a method by which DEC systems can be integrated in building projects from the early-design phases.
Giacomo Chiesa, David Pearlmutter

Chapter 9. Ventilative Cooling in Combination with Other Natural Cooling Solutions: Earth-to-Air Heat Exchangers—EAHX

This chapter focuses on the potential combination of ventilative cooling solutions with ventilative ground cooling systems. Horizontal low-enthalpy buried pipes which use air as heat fluid, for example, earth-to-air heat exchangers (EAHX), are focused on in particular. EAHXs may reduce energy consumption for space heating and cooling thanks to their potential to pre-heat and cool an airflow. This chapter describes this technique and includes design suggestions for the application of EAHX in buildings. This solution may be coupled with mechanical VC systems, or be used in naturally-ventilated buildings with the potential support of a fan system to ensure that sufficient airflow is passing through the buried pipes. Finally, a simulation-based approach to analyse the local potential of EAHX to reduce thermal discomfort in naturally ventilated buildings is introduced, thus providing a method for early-design purposes.
Giacomo Chiesa

Chapter 10. Ventilative Cooling and Urban Vegetation

The chapter analyses the potential usage of vegetation in cities to provide cooling effect due to plant evapotranspiration, shading and air flow control, discussing how lower temperatures, pressure differences and air flows can favour natural ventilation to improve comfort and reduce energy demand. Due to the urban heat island phenomenon, which is connected with the lack of green areas and the amount of surfaces with low albedo, cities face discomfort issues and higher energy demand for air conditioning. Urban greening, green roofs and vertical greening systems, depending on plant species, material used and climate, can improve environmental quality: at city scale mitigating urban heat island, improving outdoor comfort and providing additional benefits; at building scale, reducing the energy demand for cooling and favouring natural ventilation. In order to deeply address these aspects, the chapter comprises the analysis of case studies and monitoring activities related to urban greening, green roofs and vertical greening systems.
Katia Perini, Gabriel Pérez



Chapter 11. Ventilative Cooling in Residential Buildings

This chapter describes how to integrate and use ventilative cooling (VC) in residential buildings. A large set of case studies is introduced and classified in order to better define solutions for different climate and residential building typologies. Furthermore, the potential effect of ventilative cooling is analysed while design choices and techniques used are outlined.
Paul D. O’Sullivan

Chapter 12. Ventilative Cooling in Tertiary Buildings: A School Demo-Case and Parametric Analyses Under Swiss Climate Conditions (Central Europe)

This chapter focusses on the description of a school nearly-zero energy building (Minergie® labelled), which was designed to include ventilative cooling strategies to guarantee summer comfort conditions. This building includes a gym, classrooms, and office facilities. The gym, 11 m in height, uses a cross ventilation strategy, exploiting the strong stack effect, while classrooms and office spaces use single-sided ventilation. This building acted as reference building for the International Energy Agency (IEA) research project Annex 62. A one-year monitoring campaign was conducted to calibrate the simulations performed with the software DIAL + to carry out a parametric analysis on main variables that are able to influence ventilative cooling performances. Although, this building does not include in its final configuration a dwelling-unit for the school keeper, the architect designed a fictive apartment within the building, to perform parametric simulations. In this chapter it is, in fact, also reported a parametric analysis covering the following building usages: school, office and residential. This analysis allows on the one side analysis of the main issues influencing ventilative cooling performances, and on the other side verification of ventilative cooling resilience under climate and microclimate changes, showing very good resilience to both climate changes and heat waves.
Flourentzos Flourentzou

Chapter 13. Historic Practices of Ventilative Cooling a Case Study on the House of Parliament, 1836–1966

Ventilative cooling is a concern of contemporary practice, but research into the design of historic buildings has illustrate that the use of ventilation for cooling has been a much more longstanding practice. It was widely utilised in public buildings throughout nineteenth century and first half of the twentieth century, often in conjunction with other historic techniques. This chapter provides a critical examination of ventilative cooling as a historic practice, using the House of Lords as case study. This provides a setting where the challenges of cooling buildings before the introduction of mechanical refrigeration and air conditioning can be studied. Inside the two debating chambers ventilation was utilised for cooling purpose in three different ways. In addition to (1) reducing the indoor air temperature, ventilation was utilized to (2) harness the cooling effect of air movement, (3) and also to cool the architectural fabric, following the principal of night-purge ventilation. Focusing on the period from 1835 until 1950 and taking a realist perspective this chapter re-examines the experience and knowledge that users, scientific researchers and technical staff had acquired, illuminating the practical challenges of achieving thermal comfort through ventilative cooling, covering both mechanical and natural methods. This shows that historic practices not only engaged with the technological but also managerial and user-experience perspectives.
Henrik Schoenefeldt
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