A field study of natural ventilation in better insulated houses.

Describes air leakage and tracer gas (SF6) measurements made in 42 Scottish houses. Finds that leakage in the "test" (better insulated) houses are on average 10% higher than that in the "control" houses. About 40% of the total leakage rate (at a pressure difference of 50 Pa) flows into houses through thefloor boards and the air-bricks under the crawl spaces. Tracer gas measurements indicate that average leakage rates with closed windows lie between 0.52-1.65 air changes per hour. Opening a window can increase the number of air changes by a factor of 2 to 5. Window-opening observations show that there is a definite relationship between outdoor air temperature and the number of open windows, and "test" house occupants open twice the number of windows compared to the "control" house occupants in the heating season.