This paper derives some new analytical solutions for buoyancy-driven natural ventilation in buildings with three openings. The new solutions are used to analyse the effect of the middle opening height and area on the natural ventilation performance. The criteria for flow direction switching for the middle opening is established. It is also proved that the neutral plane level in the three-opening buildings depends only on geometrical parameters. Natural ventilation of buildings with two openings affecting by supply- or exhaust-only mechanical systems are also investigated analytically.

The instantaneous temperatures close to a diffuser for displacement ventilation have been measured by using a whole-field measuring method. The air temperature was measured indirectly by using infrared thermography with a digital infrared camera and a measuring screen. By moving the measuring screen the whole field around the diffuser was measured. A method has been developed for combining the tow-dimensional measurements to produce a three dimensional representation.

This study investigates the impacts of the three different types of carpark namely open (on surface), multistory and integrated carpark. The 1:200 scaled models were used in wind tunnel to gather pressure distribution data on the exterior surface of surrounding housing blocks. The data were collected from testing the various wind directions on different types of carpark. Using pressure coefficient (Cp) values, the ventilation performances represented by air change rate (ACH) in the selected units were calculated using CONTAM.

Indoor air contaminants may be grouped into four categories: microbial contaminants; respirable particles; gaseous contaminants, and vaporous contaminants. Conventional filters like HEPA filters can only be useful for bioaerosols and respirable particulate. Absorbers such as activated adsorbed can be useful for almost all gases and vaporous contaminant, but eventually they will lose efficiency. Photocatalysis can remove all VOCs and bioeffluent, but not very useful for gases contaminant such as ammonia.

This paper presents the feasibility of predicting the transient CO2 levels in a classroom. Air measurements in the classrooms were taken to determine the fresh air change rate and ventilation effectiveness by means of tracer gas method. The fresh air change rate, effectiveness, occupancy, and outdoor CO2 levels were used as inputs for prediction of indoor CO2 concentration. The general profiles of predicted CO2 concentrations are quite similar to that of the measured values. The ventilation rate is often overestimated.

One of the reasons for using displacement ventilation is that it may provide better indoor air quality in the occupied zone than conventional mixing ventilation. It is therefore important to understand the importance of the system on this aspect. A validated CFD model was employed to generate concentration distribution data for CO2, radon and moisture in a Hong Kong shop with displacement ventilation. Analysis found that the concentration distribution affected by factors such as the source type and location, its associated plume strength and human body convection, etc.

A research initiative, aimed at obtaining status-quo measurements of Indoor Air Quality (IAQ) and ventilation characteristics in air-conditioned office buildings in Singapore, has resulted in an extensive database, which details are presented in this paper. An integrated IAQ audit methodology developed during the course of the research will be presented and its application to nine buildings will be discussed in chemical, biological and particulate dimensions as well as the thermal comfort parameters.

The indoor environment is by far the most important environment from a health perspective. Allergies, airways infections, lung cancer etc. are associated with indoor air quality (IAQ) in developed countries and they are related to the use of energy for buildings. The main problems related to buildings, energy conservation and health in the developed world concern 'dampness' and inadequate ventilation. It is well established that if there is no 'building dampness' and if the ventilation is adequate then the risk of IAQ-related diseases is low.

Apart from Government's legislations and regulations, standards and guidelines, administration and publicity, ecological design [1-3] is a necessary approach to a clean environment. The fundamental rationale is to minimize the detrimental impact on our ecological environment. The study illustrates urban design and city planning are one of the "tools" and approaches to achieving the goal of a cleaner air quality, energy conservation and good, natural ventilation.

Recently the air quality has caused people's great attention, and the appraisal of the air quality has become a hot issue in the worldwide. This paper assets that the age-of-air should be an important index to evaluate the air quality. Since the architecture place becomes more and more complicate and diversity, the traditional searching method has a lot of limitations. With the development of computer technique, the superiority of computational fluid dynamics (CFD) method becomes more and more obvious, thus the CFD begins to be applied to the HVAC.