This paper evaluates the suitability of humidity-controlled house ventilation system to determine (i) the effectiveness of relative humidity as a sensing element, and (ii) the operating and performance characteristics of such ventilation strategy. The ventilation system consists of continuously running "mechanical" air extractor units and "passive" air inlet units equipped with humidity sensors. The ventilation system was installed in two single storey houses which were monitored during November 1989 to April 1990.
The indoor climate and ventilation were measured in 50 dwellings with various ventilation systems. The health and comfort of people living in the dwellings were studied with a simultaneous questionnaire. The ventilation rates measured with a tracer gas using the decay method varied from 0.1 to 1.2 m³/hm³, with an average of 0.5 m³/hm³. The ventilation rate in the bedroom was usually lower than the mean ventilation rate of the dwelling. The ventilation rates measured in a two-week period with the passive perfluorocarbon method varied from 0.2 to 1.9 m³/hm³, with an average of 0.8 m³/hm³.
In this paper a short term testing methodology is developed to evaluate the performance of ventilation systems with respect to control of indoor air pollutants. Two efficiency measures, displacement efficiency and removal efficiency, are defined based upon analysis of mass transport into and out of a specified control volume. These new efficiency measures are applied to the analysis of a ceiling based ventilation system and comparisons are made with age of air and pollutant removal effectiveness concepts.
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