Air infiltration and heat exchange.

Air-to-air heat exchangers were evaluated as a method of maintaining indoor contaminant concentration levels below acceptable levels. A mathematical simulation of air infiltration and indoor contaminant generation was used todetermine the distribution of contaminant concentrations at various average intervals including hourly and yearly. Both spot generation such as from unvented combustion, and diffuse sources, such as from materials, were considered for four contaminants, nitrogen dioxide, carbon monoxide, carbon dioxide and formaldehyde. The results of the simulations were compared to indoor contaminant concentration guidelines developed from outdoor standards and indoor recommended levels. Alternate strategies of direct exhaust of contaminants at the source and loose house construction for increased natural ventilation were also considered.