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.

In order to study the impact of the outdoor air on the indoor environment, suspended particulate matter were simultaneously sampled indoors and outdoors of a typical residential house in the Al-suwayq area. The resullts showed that the concentration of the indoor suspended particulate matter was heavily dependent on outdoors.The information obtained in this study appears to be the only data for indoor atmospheric dust collected in Oman.

A subjective study is reported in that paper concerning a field environmental chamber (FEC) equipped with a displacement ventilation system (DV). The aim of that work was to investigate effects of temperature gradient and room air temperature on local discomfort due to air air movement at different thermal sensations.