English

The aim of that study was to establish a methodology to quantify the ozone emission rate from electronic air cleaners, along with the ozone decay parameter. For that experiment 3 different portable ionisation-type air cleaners were used . The leakage rate of the stainless steel environmental chamber was measured by a tracer decay gas method. The results and conclustions are presented.

The most recent initiative taken by the Hong Kong SAR government to improve IAQ in various facilities is fan IAQ certification scheme for offices and public places. This paper outlines the key elements of the scheme , discusses the suitability of the IAQ criteria, and identifies the difficulties in meeting the prescribed measurement protocols.

Stacks can enhance the natural ventilation of buildings. They can drive ventilation in floors where there is little heat load. In this paper, the use of stacks for second ventilation has been investigated with laboratory experiments and supporting quantitative models. Results and conclustion are presented.

Do multiple solutions of natural ventilation exist in complex buildings and what are the physical mechanisms that can lead to a such existence ? To answer that question the authors have examined a simple one-zone building with four openings using the simple macrocospic method of thermofluid modelling and have made a simulation of the four-opening building with a conventional network modelling computer program .
The results show a good agreement between the predicted ventilation flow rates by the network modelling method and the simple analytical solutions.

The evaluation of a quantitative method for culturing particles on HVAC filters is the aim of this research. Two phases for that study : first, a case study comparison of two HVAC filters from a building with a history of IAQ concerns and secondly remediation efforts in the same building. This limited study has been carried out for prelimimary assessment of the use of a filter quantification method to evaluate relative airborne fungal load.

This paper studies particle diffusion of a wide range of particle sizes compared with the diffusion of passive contaminant under the same conditions. A numerical model was validated then simulation of diffusion of particles in 2 different clean rooms was made. The results show that ventilation mode, particle source location and air exchange rate have an influence on the particle distribution.

A new concept, called Integrated Accessibility of Contaminant Source (IACS), has been proposed to consider simultaneously the positioning of a contaminant source, the distribution of occupants along with the overall airflow pattern. 84 cases with different combinations of contaminant sources and ventilation style in a full-scale room have been investigated numerically for that study. From the results obtained, some rules are proposed to advise the best ventilation strategies for different situations.

For that study, numerical simulations along with full-scale laboratory experiments have been carried out to investigate the influence of the porous screens on the temperature fields, flow fields and ventilation rates within the kitchen.The air exchange rate and the age of the air in the kitchen were measured with the tracer gas concentration decay method. Concerning the understanding of the temperature and flow distributions, a CFD analysis was performed.

The modified T-method can be applied to the prediction of the flow distribution in multi-fan duct systems. The method has been tested on the single-fan duct system presented in the ASHRAE handbook, the results obtained were in adequation with those published. So a symetry of a two-fan duct system has been investigated. It worked well. In order to evaluate the capability of the modified T-method simulation for multi-fan duct systems, a bathroom ventilation system in a 20 storey residential building was tested . The results are satisfactory.

For that study CFD models have been developed to simulate the transport of infectious droplets and bioaerosols in a hospital ward. Those models will help for the design and control of a local exhaust ventilation (LEV) system. Details of the CFD models are reported in this paper along with the analyses of the distribution and suspension time of droplets and bioaerosols with respect to their size, emission direction and emission speed.