Relating actual and effective ventilation in determining indoor air quality

Abstract Ventilation is both a mechanism for removing indoor air pollutants, and a potential energy load on the heating or cooling system of a building. Quantitative estimates of the ventilation rates, important for both of these applications, necessitate determining time-averaged quantities. The time-averaged ventilation rate appropriate for indoor air pollution, however, is different from that associated with energy load. We derive ventilation efficiencies for well-mixed, homogeneous, time-varying concentrations and corroborate findings with field data from a test house in Edmonton, Alberta, which indicate that monthly ventilation efficiency ranges from 79% to 92% with an annual average of 80%, and that hourly temporal ventilation efficiencies vary over a much larger range than time-averaged quantities.