Ventilation air infiltration and building occupant behaviour.

The role of the occupant in buildings energy use has been evident in studies in many countries. Our experience since the early 1970's has indicated that energy use can vary by at least a factor of two solely on how the occupant operates the house or apartment. This often involves window use. For example, window and door openings, to cool an overheated dwelling, can take place at any time of the year. This paper describes work at Princeton which measured occupant ventilation behavior, and which provided feedback in an attempt to modify behavior. Experiments have been conducted about the effect of informing the occupant as to when outdoor temperature is low enough that window opening would be the better choice than employing mechanical cooling methods. A small blue light visible to the occupants was used to supply this guidance, in conjunction with feedback to the occupants about cost. In a large multifamily building, regular visual inspection of window openings, sometimes supplemented with infrared scanning, were used to identify the prevalence of these actions. Fan pressurization tests in the apartments indicated very tight construction with the windows closed. When comfort and perceived ventilation needs conflict with energy conservation, poor temperature regulation can be the culprit. In another study, data were collected through open-ended interviews and a survey in the same multifamily building. Interviews asked about beliefs concerning need for fresh air, stuffiness, and perceived thermal comfort. In this building, which most residents considered too warm in the wintertime, window or door opening was typically used to reduce indoor temperature. Blower door tests were used to estimate infiltration in a single apartment at differing window apertures while energy balance calculations based on measured energy consumption and temperatures were used to estimate infiltration for the entire building. Tenants' reports of their perceptions are used to interpret the observed and reported ventilation behavior. Tenant perceptions are also related to measurement-based estimates of air infiltration rates.