The use of openable windows by the occupants of offices.

Describes the results of a series of observations of window opening by occupants of 200 small offices in 5 buildings. Shows a high degree of association between the number of windows open and weather-related parameters. Estimated ventilation rates based upon the proportion of windows open, indicate levels substantially in excess of those required for indoor quality control, for a large part of the heating season. Discusses results in relation to predicted thermal performance of the 5 buildings considered, taking into account factors such as window size, area of glazing, orientation and thermalproperties of the structure.