Evaluation tool of climate potential for ventilative cooling

… -AMERICAN SOCIETY OF …, 2002

European residences to control indoor air quality and provide thermal comfort. Increasingly, European building designers have turned to natural ventilation to control air quality and cool commercial and institutional buildings as well, hoping to take advantage of the potential of natural ventilation systems to conserve energy associated with mechanical cooling and fan operation. Encouraged by the early successes of the past decade, European building designers have advanced natural ventilation technology, introduced promising hybrid ventilation technologies that combine mechanical and natural means, and developed analytical tools for the design of these systems. These systems may be adapted to the North American context, but much work will need to be done to realize the full potential natural ventilation may offer to North America. The needed work includes modeling studies that may require advanced simulation tools to adequately model the complex coupled thermal and airflow dynamics.

2011

2008

Objective of this study is to compare the cooling potential of diverse passive cooling techniques linked to ventilation: controlled thermal phase-shifting (a recently discovered phenomenon), air-soil heat exchangers, evaporative cooling, and direct night cooling. The potential of these techniques is investigated for the case of an administrative building located in a moderate climate, with a specific attention to urban versus rural location, as well as normal versus extreme summer (of type 2003). Simulated building response is analyzed for a variety of constructive and operational configurations (solar protection, thermal mass and insulation, internal gains), in free floating mode as well as with auxiliary cooling backup.

2014

Higher insulation and air tightness levels of buildings, increase the risk on overheating. Ventilative cooling as passive technique can limit overheating and decrease cooling energy consumption. The national energy performance regulations (EPBD) determine whether, how and under which requirements ventilative cooling can assist to reduce cooling demand and overheating. Therefore, those regulations are a key factor in the market uptake of ventilative cooling. Without a realistic and achievable approach, ventilative cooling will marginally be applied in buildings. In this study, actual and possible requirements imposed on devices or systems for ventilative cooling are described. Besides, a sensitivity analysis is performed to assess the impact of parameter variation on the ventilative cooling effect. One reference dwelling is selected and introduced into the EP software of Belgium, The Netherlands and France. In that way, differences in buildings characteristics between countries on the output are ignored. Of course, the presented results are only valid for the selected reference dwelling. In the three countries ventilative cooling by means of openable windows can be taken into account, in Belgium and France as a percentage of openable windows, in The Netherlands as present or not. Burglary resistance and water tightness of ventilative cooling devices are requirements (for The Netherlands) or have an impact on the performance of the ventilative cooling device (for Belgium). In France, openable windows are not allowed in case of active cooling. When there are openable windows in France, they are supposed to be opened during the heating season as well, resulting in an increased heating demand due to ventilative cooling. As can be expected, ventilative cooling always decreases the cooling demand (26 to 96% in Belgium, 10 to 35% in The Netherlands), especially in combination with mobile solar shading. Similar to the cooling demand, the risk on overheating in Belgium decreases by applying ventilative cooling. In France, summer indoor temperature can be strongly reduced by using openable windows, although the fraction openable windows has no effect. Next to ventilative cooling, thermal capacity as well as solar shading can have a considerable impact on summer comfort and should be considered as complementary means. The overall primary energy consumption of the reference dwelling is lower when ventilative cooling is applied (5 to 12% in Belgium, up to 4% in The Netherlands) except for France where openable windows remarkably increase the heating demand (up to 38%). The lowest primary energy consumption is achieved by applying ventilative cooling in combination with sun shading.

2014

International audiencePassive cooling through window airing presents a promising potential for low energy houses in order to avoid overheating risks and to reduce energy consumption of air conditionners. One barrier against this solution is the complexity of evaluating air flows, which limits the use of natural ventilation during the design phase of a building. This study aims at analyzing a characterization and modelling process allowing natural ventilation to be accounted for in the evaluation of energy performance and thermal comfort of a single-family house. The evaluation of summer comfort and passive cooling performance will be compared to measurements performed on a zero energy house Maison Air et Lumière, located near Paris. Window characterization, on-site air flow measurements, as well as ventilation evaluation method will be described in this paper; the accuracy of the evaluation method (ventilation flow rates and thermal comfort) will be assessed thanks to a specific mea...

Energy Conversion and Management, 2013

Energy consumption for cooling is growing dramatically. In the last years, electricity peak consumption grew significantly, switching from winter to summer in many EU countries. This is endangering the stability of electricity grids. This article outlines a comprehensive analysis of an office building performances in terms of energy consumption and thermal comfort (in accordance with static-ISO 7730:2005-and adaptive thermal comfort criteria-EN 15251:2007-) related to different cooling concepts in six different European climate zones. The work is based on a series of dynamic simulations carried out in the Trnsys 17 environment for a typical office building. The simulation study was accomplished for five cooling technologies: natural ventilation (NV), mechanical night ventilation (MV), fancoils (FC), suspended ceiling panels (SCP), and concrete core conditioning (CCC) applied in Stockholm, Hamburg, Stuttgart, Milan, Rome, and Palermo. Under this premise, the authors propose a methodology for the evaluation of the cooling concepts taking into account both, thermal comfort and energy consumption.

Fluids

Energy consumption due to cooling and ventilation of buildings has grown significantly within the last two decades, and therefore advancement in cooling technologies has become imperative to maximise energy savings. This work numerically investigates the performance of vapour-compression unitary and centralised cooling systems for high rise buildings using an office case-study in the United Arab Emirates (UAE). Energy modelling, thermal comfort and indoor air quality analyses have been carried out using the Integrated Environmental Simulation Virtual Environment (IES-VE). Using the benchmark system based on fan-coil units, the findings have indicated that attaching a Variable Speed Drive (VSD) fan can reduce the overall energy consumption of the building by 8%, with 20% reduction in the cooling loads. The unitary cooling system operating on variable refrigerant flow principle achieved an energy reduction of approximately 30%; however, this system is not recommended in high-rise buil...

Proceedings: Indoor Air (2002), Monterey, CA, 2002

Increasingly, European building designers have used natural ventilation to control air quality and cool commercial buildings to conserve energy compared to mechanical cooling and fan operation. These advanced natural and hybrid ventilation systems may be adapted to the North American context, but work is needed including consideration of the broader diversity of climates. An approach to the analysis of climate suitability is presented and applied to a number of North American climates. The climate suitability method presented offers an approach to predesign analysis for ventilative cooling that is climate specific and accounts for the expected level of internal and solar gains for a building. The climate suitability analysis also yields estimates of ventilation rates that are likely to be needed to achieve either a direct ventilative or night cooling design strategy.

Architectural Engineering and Design Management, 2019

This paper evaluates the use of advanced natural ventilation (ANV) strategies in a range of climatic conditions from four cities in the UK using dynamic thermal simulation. A prototype ANV system was proposed, through which design changes were made to determine the most effective case in mitigating overheating among the changes considered. The most effective case was then assessed under identical simulation conditions for all four ANV strategies. The overheating criteria used in the research include the single temperature criterion from the Chartered Institute of Building Services Engineers' (CIBSE) Guide A and the adaptive thermal comfort overheating criteria from BS EN 15251. Both the current and future 'Design Summer Year (DSY)' weather data were used to examine the thermal performances of the proposed design. The findings show that shading, night cooling and heavy weight structures (ceiling) were all useful in mitigating overheating, with night cooling being identified as the most effective measure. The work assessed the use of ANV in both current and future scenarios to quantify the limits of outdoor environmental conditions under which natural ventilation is an effective strategy for achieving thermal comfort. The adaptive thermal comfort overheating criteria were proved to be easier to meet compared with the CIBSE single temperature criterion. With the adaptive overheating criteria, the given design is predicted to not overheat until 2050 in London Heathrow; and for other places evaluated in the UK (Edinburgh, Manchester & Birmingham), the design passes these criteria. However, with the single temperature criterion, the design fails for all London Heathrow weather data and some of the Manchester weather data. The Centre-in ANV strategies proved to be more effectives than the Edge-in strategies for space cooling due to the extended structure thermal mass. To make designs future proof for overheating in the southeast of the UK, hybrid or mixed ventilation may be needed in the foreseeable future.

The thermal comfort of the residential buildings Sunlighthouse in Austria and LichtAktiv Haus in Germany are investigated with a particular focus on the summer situation and the role of solar shading and natural ventilation. The houses have generous daylight conditions, and are designed to be CO 2 neutral with a good indoor environment. The thermal environment is evaluated according to the Active House specification (based on the adaptive method of EN 15251), and it is found that the houses achieve category 1 for the summer situation. It is found that ventilative cooling through window openings play a particularly important role in maintaining thermal comfort in the houses and that both window openings and external solar shading is used frequently. The occupants have reported their thermal sensation daily during most of a one-year period. The thermal sensation votes show good correlation with the thermal comfort category.