Since the beginning of this decade, natural ventilation in office buildings is receiving specific interest. There are two sorts of application. Natural ventilation can be a strategy for indoor air quality control. Besides it can be used as night ventilation during warm or hot periods. In this case the objective is to cool down the thermal mass and improve the thermal summer comfort. The EC JOULE NatVent project wanted to identify the barriers to the application of natural ventilation in office-type buildings in moderate and cold climates and to provide solutions.
This paper describes the results coming out of the European Commission supported THERMIE Target Project Energy Comfort 2000. This was the first Target project, containing eight non-domestic buildings, started in July 1993 and to be completed at the end of 1998. The project aimed to design and construct buildings which use less than 50% of the energy of a traditional equivalent, by using passive methods, particularly to avoid the need for air-conditioning. High quality internal conditions were to be achieved.
Natural ventilation can be a part of a strategy for a good indoor air quality. It can also be a way to realise night time ventilation during warm periods. In this latter case, the aim is to cool down the thermal mass of the building to obtain a better thermal comfort during daytime. Night time ventilation requires high ventilation rates and sufficient accessible thermal mass. The ventilation openings have to be well designed to avoid undesirable effects like rain, pollution and burglary.
The present research applies the N3S 3D finite element CFD code to the air flow simulation on a well-known dwelling building located in South of Switzerland, the " Maison Ronde " of the architect Mario Botta. The summer night refreshing effect is examined when crossing ventilation due to the wind creates indoor air motion and for cooling walls and ceilings surfaces. To be realistic, the simulation takes simultaneously into account the three main aspects of the problem: - determining boundaries conditions.
In 1993, the Open University in Milton Keynes, UK, refurbished the open-plan first floor Design Studio in their Publishing Department to use natural ventilation to keep the interior cool. At the same time the third floor, which was not suitable for passive cooling, was fitted with mechanical comfort cooling units and the intermediate floor was not changed. This paper compares tl1e thermal performance of the three floors and discusses the results of a staff-satisfaction survey conducted among the occupants.
The objective of this study is to propose a simplified characterization of thermal inertia, as part of the installation of a system of summer refreshment by means of nighttime cooling ventilation. On the basis of a previous study, conducted by relying upon a modal analysis, the interactions between the thermal inertia of a building and the variation of the air exchange rate have been explained.
The present paper aims to investigate, in a systematic way, and by using both experimental and theoretical tools, the potential of night ventilation techniques when applied to full scale buildings, under different structure, design, ventilation, and climatic characteristics. Also, to investigate the impact and the limitations of night ventilation techniques regarding the thermal behavior of various types of buildings. Real scale measurements in three buildings operating under free-floating and air conditioning conditions have been performed.
Natural night-time ventilation is often used to pre-cool low energy buildings, but can lead to security risks and weather damage. A prototype night ventilator has been built to combat such problems, but how has it performed in field tests?
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