Passive ventilation to maintain indoor air quality

Abstract

The results of a three-year project to measure the effectiveness of passive ventilation for houses are presented. The feasibility of using passive ventilation was studied to provide a simple maintenance-free alternative to the mechanical ventilation systems that are required by Canadian Standards Authority and American Society of Heating, Refrigeration and Air Conditioning Engineers standards to maintain acceptable indoor air quality for occupants. It was found that most detached single story and two-story houses are adequately ventilated in winter by natural air infiltration with no passive vent openings. Townhouses, with two walls common to adjacent units are usually not adequately ventilated by natural infiltration. Even with several large ground-level passive ventilation openings houses cannot be adequately ventilated in summer and spring/fall seasons in light winds without using large open area vents that cause over-ventilation in winter. The major obstacle to adopting passive ventilation is an inlet damper control that is regulated not only by outdoor temperature but also by windspeed. Such windspeed sensitive controllers are not commercially available, and are likely to be expensive and prone to malfunction if they use existing wind speed sensors. 40 refs., 51 figs., 65 tabs.