The present paper reports on tracer gas measurements performed in five large buildings during normal operating conditions. In all buildings air was supplied through ceiling diffusers and returned through a ceiling plenum. The measurements were taken during summer with the systems in cooling mode, i.e. the supply temperature was lower than the room temperature. The global air change effectiveness and the occupied zone average air change effectiveness were calculated based on the age-of-air concept.

Avery largeelectronics factory had beencompletely refurbished, and new mechanical ventilation systems installed. In an area of the factory where the principal activity was the bench assembly of small components, there were persistent complaints of eye nose and throat irritations, and absenteeism among the workforce was excessive. Careful examination of the environment had failed to identify any significant contaminants in the air. The situationwas similar to the SickBuilding Syndrome in office buildings.

This paper describes a method for measuring tbe dispersal of airborne contaminants by light-sheet illumination of aerosol tracen and digital image processing techniques. The goals of the research were twofold: to use field-portable and safe equipment to make near-instantaneous measurements of tracer aerosol concentrations over arbitrarily positioned two-dimensional planes of near-mom dimensions; and to carefully define similarity conditions under which aerosol dispersal can be considered an accurate surrogate for passive molecular dispersal.

This paper deals with the problem of the weather influence on ventilation rate for naturally ventilated buildings with purpose provided openings and vertical shafts. Hitherto, it has not been possible to predict the ventilation rate or to extrapolate it for other weather conditions than the measured ones, without performing a heavy calculation exercise by means of running a computer program. In the paper a prediction as well as an extrapolation procedure is outlined . The procedures are based on generalised output data from a single zone infiltration and ventilation model (AIDA).

Airtightness deficiencies of building envelopes and weaknesses in the ventilation systems can disrupt the operation of heating and ventilation systems. This can lead to an insufficient level of air quality and higher energy consumptions. In order to assess the performances of buildings and ventilation systems, CSTB has designed and developed different experimental devices for field testing. In a first step, an equipment was produced to measure the envelope air leakage. This apparatus is mainly used for research purposes.

The classification of outdoor (ambient) air as fresh for the purposes of ventilation is not always appropriate, particularly in urban areas. In many cities of the world, urban air frequently violates health-based air quality standards due to high ozone concentrations. The degree of protection from exposure to ozone offered by the indoor environment depends on the relationship between indoor and outdoor ozone levels. Existing concentration data indicates that indoor/outdoor ozone ratios range between 10 and 80%.

The purpose of this study was to carry out a mathematical modelling analysis of the effect of indoor pollutant source strengths and ventilation rates on the concentration of pollutants. These concentrations are then compared to various human exposure limits and targets. The modelling was carried out for a variety of ages of residential detached housing for a range of Canadian climatic conditions. Although a literature search was performed, pollutant source strength data for housing was not generally available.

The occupant's behavior with respect to window opening may greatly affect the ventilation system, the energy consumption orland the indoor air quality. In order to quantify the magnitude of opening times, many surveys have focused on climatic parameters and concluded to the temporal correlation between the timelength of opening and the outside temperature or the solar irradiation. In this paper, we study the influence of sociological and technical parameters on the average time of opening during the winter.

This paper reports the results of humidity and ventilation measurements in occupied residential buildings to study the effect of airborne moisture movement on condensation risks. The dwellings have been fitted with a cooker hood and an extractor fan (both with variable speed control) in the kitchen and an extractor fan in the bathroom.

Ventilation systems in dwellings should not only maintain the quality of the air, in other words limit pollutant concentration whatever the origin, but protect the structure, that is, limit condensation and the storage of excessive humidity in existing materials. Domestic ventilation represents a significant element of energy loss. It is a function that should be provided at minimum cost in terms of energy and therefore be directly dependent on fresh air requirements. Hence the introduction on the market af socalled hygro-adjustable ventilation systems.