English

Ventilation system has to be design in order to strike a balance between indoor air quality and energy requirements.So, the ventilation efficiency can be considered as a major issue to deal with this objective. In order to assess the efficiency of pollutant elimination from a room, a methodological approach using CPD has been developed. It is based both on local and global indexes. These indexes take into account the distribution of pollutant concentration inside room and the mean concentration at the exhaust with respect to the occupant location.

An equation is developed for predicting the combined effect of naturally and mechanically induced air flows in buildings and solved by a combination of analytical and iterative methods. The resulting two-dimensional formulation, implemented as a simple computer program, allows rapid, hourly simulation of infiltration in domestic-scale buildings with a range of ventilation strategies.

Air movement can provide desirable cooling in "warm" conditions, but it can also cause discomfort. This study focuses on the effects of turbulent air movements on human thermal sensations through investigating the preferred air velocity within the temperature range of 26°C and 30.5°C at two relative humidity levels of 35% and 65%. Subjects in an environmental chamber were allowed to adjust air movement as they liked while answering a series of questions about their thermal comfort and draft sensation.

This study involves comprehensive experimental measurements and CFD simulations in a mockup of a full-size classroom with realistic loads. Four different air distribution systems have been tested:

Ventilation requirements for vehicular tunnels in the Hong Kong Special Administrative Region are discussed. For vehicle emissions, carbon monoxide is considered to be important for vehicles running on petrol engines, and suspended particulates for diesel engines. Other environmental control parameters are temperature, air speed and air pressure. Codes, regulations and design guides for ventilation systems are reviewed. Different ventilation designs adopted in local vehicular tunnels are described.

The effects on pressure loss of the separation and orientation of closely coupled duct fittings in RVAC systems were investigated using computational fluid dynamics to analyse the pressure distribution in a system containing two 90° bends in two common configurations; an S bend and a U bend. Fittings that are separated by less than 8 to 10 hydraulic diameters· of the duce behaved in very different ways depending upon the orientation of the fittings in relation to one another.

19 university students were asked about their thermal comfort while attending ordinary lessons in a displacement ventilated test room of typical classroom size. Two different ceiling heights were tested. Both the general temperature level and the strength of the vertical temperature stratification in the room increased continuously during the lessons due to the presence of the students, however slower with the higher ceiling.

Researches into natural ventilation characteristics of courtyard buildings have been carried out extensively in climates very different from tropical climate. Nevertheless, courtyards have been incorporated for centuries in traditional shop houses and also adopted in many modern commercial buildings in tropical countries such as Singapore. This paper discuses a study to investigate the natural ventilation characteristics of courtyard buildings in Singapore. Four typical courtyard buildings are examined.