The effectiveness of range hoods and window fans in removing indoor pollutants is considered. Tests were conducted in a two-room test space with an infiltration rate less than 0.1 hr-1 using sulphur hexafluoride as a tracer gas. Range hood te

Based on the age concept, the performance of the following three principle ventilation schemes have been monitored (supply air terminal - extract air terminal), ceiling-ceiling, ceiling-floor, floor-ceiling. All systems used only air for both heating and cooling. Contaminants with both greater, less and approximately the same density as air were released at a point source. The tests were both carried out in an empty room and with a person (heated mannekin) in the room.

The indoor air quality depends on several different factors. One is the air flow or air movements within the building and through its external walls. These flows are governed by the type of leakage openings and the pressure differences across the walls and the air terminal devices. The pressure differences are caused by wind, thermal and fan forces. Mathematical models can be used to calculate the different air flow rates. A simple example is used to demonstrate magnitude and consequences of this air leakage for two different ventilation systems.

Minimising ventilation for energy conservation in buildings requires that ventilation efficiency be high. The common practice of locating supply outlets and return inlets in or near the ceiling creates an opportunity for air tobypass from the supply to the return without mixing in the occupied space. Equations are derived for calculating efficiency and stratification factor from tracer gas decay measurements.

The paper shows that age analysing techniques are an excellent tool to assess ventilation effectiveness. It is important to differentiate between air exchange effectiveness and contaminant removal effectiveness, having continuous generation of contaminants. Only when a source is homogeneous andpassive, are the age of the air and the contaminants in the room equal. However, the air exchange effectiveness accounts for the removal effectiveness of the contaminant left in the room when the generation stops.

Aerodynamic phenomena affecting the ventilation process, such as aerodynamic mixing, generation of secondary and slightly turbulent flows, roof contours, infiltration and convection and their connection with geometric parameters of the object and energy expenditure for ventilation are analysed.

Notes the contaminants which may be contained in room air - radon, solvents, tobacco smoke, formaldehyde, dust mites etc. Points out that no definitive threshold values have been established for contaminants representing health hazards. Points out that the reactions of various individuals to them differ widely, determined by a number of factors.

Examines evidence for relating sickness to the office environment. Notes research into the office building syndrome (obs) in various countries. Notes that although air conditioning goes back to the 1920s, obs has been in the news only during the last five years or so. Notes the contribution to this of energy saving regulations. Notes the complex nature of indoor air contamination. Points to obvious factors such as air conditioning systems unserviced for 30 years, occupational psychology, indoor architecture, climatic constance and air ionisation.

Looks briefly at current research into developing techniques for measuring and predicting natural ventilation and infiltration rates in buildings.

Notes that the information in the ASHRAE 'Fundamentals' volume on how much ventilation ought to be provided is based on work nearly 50 years old. Reports new work on permissible ventilation rates produced by H B Bouwman of the Dutch Research Institute for Environmental Hygiene of the Central Organisation for Applied Scientific Research TNO. The numerical purpose of the work was to find the rate of ventilation required to keep complaints from occupants of rooms about unacceptable smells to less than 5% or 1%.