Pre-Occupant Departure Hvac Shutdown: A Strategy for Energy Conservation

Abstract

The human response to the thermal environment depends in part on the temporal nature of the exposure. One aspect of the temporal dimension includes ramps or drifts that are brought about when the heating or cooling system is turned off. When this occurs, the shape of the drift depends upon the outside temperature and wind velocity, the solar load; the building shell, the location of the occupant and the indoor thermal load including the occupant density and machinery. The Honeywell Corporation in Arlington, Illinois has developed a model that will predict the temperature drifts at various locations within the occupied space when the HVAC system is shutdown. This regulation of the office temperature before workers leave for the day represents an energy saving strategy. The purpose of this study was to examine the comfort response of humans when exposed to drifts that began 0.5 h and 1.0 h before the normal departure of the employees. Drifts were examined at 4 locations: interior, west side and north side; a control “no-drift” condition was also used. The results showed for the 1.0 h drift that no source of variance was significant for the Thermal Comfort votes. Location, however was significant for the Thermal Sensation votes. For the 0.5 h drift the only significant source of variance was the location x sex interaction for the Thermal Comfort votes. A discussion of the implication of the results as an energy conservation strategy is provided.