In order to provide comfort in a low energy consumption building, it is preferable to use natural ventilation rather than HVAC systems. To achieve this, engineers need tools that predict the heat and mass transfer between the building's interior and exterior. This paper presents a method implemented in some building software, and the results are compared to CFD. The results show that the knowledge model is not sufficiently well described to identify all the physical phenomena and the relationships between them.

This paper describes a concept of probability-based design and its application in the field of ventilation. The path of probability-based design is followed with the help of examples concerning the air change rate caused by natural and mechanical forces. The object of this study is a low-rise building situated in two different climatic zones. Evaluation of the probability of failure gives a background for probabilistic design.

Earth heat exchange (EHX) through buried horizontal air ducts (EHXair-hor) can be an effective passive/hybrid system to reduce heating and cooling loads in temperate climate zones. This paper shows the results of field testing, by the authors, of a buried pipe system for a single family dwelling and the design development of a large EHXair-hor system for a High School building. The monitoring plan for the latter is also described. Considerations on critical aspects, such as the terrain warming effect of EHXair-hor systems are also outlined.

Night cooling is promoted worldwide as an effective tool to reduce refrigerative cooling demand. However it is clear that, as long as the potential for night cooling is not standardised and integrated into building energy performance calculations, its application will be strongly hampered. In this paper the practical experiences of night cooling in an office located in Belgium are first discussed.

This paper presents an experimental and numerical analysis of building cooling using night-time coldaccumulation in phase change material (PCM), otherwise known as the free-cooling or passive-cooling principle. The phase change materials were used in ceilings and floors. The free-cooling principle is explained and some of the types of PCMs suitable for summer cooling are listed. An experiment was conducted using paraffin with a melting point of 22 C as the PCM to store cold during the night and to cool hot air during the daytime in summer.

The cooling effect of indoor air movement from circulator fans has been discounted in many strategies for increased energy efficiency. Standards such as ASHRAE 55-2004 clearly provide thermostat offset guidance for indoor air movement to maintain the comfort of sedentary occupants. The Standard is ambiguous on the cooling effects of air movement for non-sedentary activity. US utility company Exeloncorp, has indicated that each 1C increase in summer thermostat setting will save 5.4% to 7.2% of cooling costs.

In France there is an increasing demand for energy efficient and environmentally friendly buildings of high thermal comfort. Balanced ventilation systems with heat recovery on the exhaust air and earth to air heat exchangers (EAHEX) are interesting techniques which can reduce the heating and cooling demand of buildings, and improve internal thermal comfort. A numerical study was carried out to evaluate the impact of these two systems on the energy performance and internal thermal comfort of a dwelling, with respect to the French climate characteristics.

The objective of heating, ventilating and air conditioning (HVAC) systems is to satisfy users when it comes to health, indoor air quality (IAQ), and thermal comfort. Air conditioning systems employed to provide thermal comfort and indoor air quality consume a significant part of building energy requirements. Any effort to minimise energy consumption improves cost effectiveness and economics. A variable air volume (VAV) system is a choice in that direction. In this research, a relative energy consumption analysis of a constant air volume (CAV) system and VAV system has been performed.

Natural ventilation using open windows is an energy efficient and effective method of providing a good indoor air climate in schools. However, open windows not only let fresh air into the building but also external noise. The availability of automatically controlled windows enables precise control over the window opening distance in comparison with manually operable windows. This paper considers the benefits of using small opening distances to provide sufficient ventilation for a good indoor climate as well as attenuation of external noise.

Active thermal mass strategies can be used to enhance the performance of thermal mass through integration with the heating, ventilation and air conditioning (HVAC) systems. Dynamic thermal modelling is required in most cases to accurately determine the performance of its integration with the environmental systems of the building. This paper describes the use of a commercially available dynamic building thermal program to construct models for active thermal mass strategies and compare the results with monitored temperatures in buildings incorporating the strategies in the UK.