Opportunities for Demand Controlled Ventilation

M ODERN HOUSES HAVE been built more airtight in order to reduce drafts, to avoid condensation damage, and to reduce energy use. However, the increased airtightness has resulted in increased levels of pollutant concentration from building materials and from occupant-related activities. Continuous ventilation is used to improve the indoor air quality in these tightly built houses. However, this continuous ventilation results in high heating and cooling energy losses and high operating energy use due to fans. The high heating energy losses can be reduced if heat recovery is used, however, the heat recovery systems are quite expensive to install. In order to break out of this cycle of creating problems with each new solution, we need a better understanding of the problem. Solutions should be developed that have minimal impact on other systems. The problem consists of two parts: ~ high levels of building airtightness, which, at times, result in inadequate amounts of fresh air being supplied by natural means, to dispose of the missions from ~ pollutant sources A significant fraction of new conventional houses in Canada are sufficiently airtight that some pollutant concentrations are exceeding safe levels [1]. The new National Energy Code for Houses and energy efficient housing programs are encouraging even tighter houses. Houses in the R-2000 pro-