The occupants of buildings are exposed to a range of aerosol contaminants, of both indoor and outdoor origin; at present, filtered mechanical ventilation is the only effective means of airborne particulate control in polluted urban areas. Significant energy costs may be incurred, however, through the large pressure drops associated with membrane filtration. An alternative to filtration might be the enhancement of aerosol deposition on a protruding surface which is parallel to the incoming airflow direction, but which does not significantly retard the airflow.

Microbial monitoring of the indoor environment can be performed in several ways and with the aid of different techniques. Knowing the limitations of the chosen system is of vital importance for the correct evaluation and interpretation of the results. The number of Colony Forming Units (CFU) detected by one method can not be directly compared with results from another method. The paper presents an evaluation of commonly used instruments for the collection and counting of airborne viable particles.

Several studies have shown that the lowest concentrations of contamination in operating theatres are achieved by using fabric covered laminar airflow systems. These systems are distinguished due to the low turbulence intensities in the protective areas. An examination in a special designed test facility was done to get further information about the relation between the turbulence intensity and airborne contaminations. In a first stage the dispersion of airborne contaminations was examined.

A new experimental set-up to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust related problems in rooms, there is a need for better understanding of the mechanism of dust deposition and resuspension.

The process of air exchange can be described through both planar and spatial network system. It depends on a few random variables (those related to climate) and also on controlled variables (i.e. those like arrangement, etc.). Consequently, the air exchange problems are solved only approximately. In order to avoid that, a neural model was applied as well as estimation in the so-called learning process with simultaneous weight correction. On the basis of comparison with experimental data it can be claimed that solutions presented in the paper demonstrate high result congruence.

This paper introduces the infrastructure of Microflo CFO modelling system in conjunction with the virtual simulation environment. The theoretical basis is described and particularly the graphical user interfaces for pre and post processing are described in detail. Features of the Microflo system are further demonstrated through its application in the design projects.

Improvement in methods of air flow pattern scale modelling in large enclosure requires above all, précising the conditions necessary in the model in order to maintain Reynolds number independence of the mean flow, as well as defining ways in which the flow turbulent structure could be simulated. The paper presents the results of experimental analyses of air velocity fields in scale models in the range of Reynolds number 1850 to 98000. The field maps of air velocity mean value were tested.

Cheap 3D models for visualization of room ventilation applications are now available. VRML (Virtual Reality Modelling Language) is found to be a good format to describe buildings, rooms and furniture. A 3D model in VRML can be placed on an World Wide Web www page and others can see the model in "Walk Through" mode. Use of VRML is described with examples as for instance in planning of measurements and as a basis for geometry in CFD calculations. The advantage of 3D and VRML is that it is much easier to see, find and correct problems than using traditional drawings.

Previous full scale experiments gave us a global and qualitative understanding of the gas circulation in a ventilated room in case of fire. In order to go thoroughly in the knowledge of these phenomena, we have built a scale model to perform more precise temperature measurements and more complete tracer gas experiments. The results show the existence of two zones when the air inlet is near the floor. At the opposite, when it is near the ceiling the room can be considered as a one single zone.