English

The acceptance and appreciation of ventilation systems is mainly determined by the perceived indoor air quality, thermal comfort and noise. Noise in relation to ventilation systems can be divided into three categories: outdoor noise (entering the dwelling through ventilation openings, cracks, mechanical supply and exhaust openings etc.); noise generated by components of the ventilation system; the impact of ventilation systems on sound reduction of partitions (between dwellings, rooms etc.). Depending on the type of ventilation system, one or more of these aspects are of concern.

The research community as well as the design and construction practice is spending a lot of efforts and investments in developing systems which optimise the energy use for achieving certain specified air flow rates. For example, improvements in efficiencies of 10 % in heat recovery systems would be considered as remarkable. At present, one observes a tremendous difference in the ventilation requirements in various countries as well as at the European level.

The LTEE laboratory of Hydro-Quebec, in collaboration with Canada Mortgage and Housing conducted an indoor air quality study involving 30 single family detached houses heated with electric baseboard heaters in the vicinity of Trois Rivières during the 1993-94 heating season. The houses were selected according to the measured air leakage at 50 Pa, so as to have a sample distribution similar to the distribution of air leakage of houses in the province of Quebec.

The effect of recirculation on the age of air is described. A new effectiveness measure called the relative air-change effectiveness is defined in such a way that the air distribution pattern in a room may be quantitatively characterized even when the age of the supply air is non-zero. This admits the evaluation of air distribution patterns in single-zone systems that recirculate air, and also multizone systems with or without recirculation.

This paper reports the findings of a pilot field study carried out to investigate the internal and external air pollution levels of two adjacent buildings, one naturally-ventilated and the other air-conditioned in an urban area, to investigate their relative attenuation of external pollution levels and to compare internal levels with existing air quality guidelines. Concentration levels of sulphur dioxide, nitrogen oxides, carbon monoxide and carbon dioxide were monitored.