Center for the Built Environment

Moving air has long been used to provide comfort in warm environments. Provision for indoor air movement was one of the wellsprings of traditional architectural design in warm regions, affecting building form, components, and equipment over millennia. However, this design option has faded from practice since the advent of air-conditioning, in which the focus has been on controlling temperature and humidity. Despite the fact that air movement can be an energy efficient alternative to air cooling, it became viewed more as a possible source of undesirable draft, and comfort standards came to set room airspeed limits very low, even for temperatures as warm as 26ºC (79ºF). An exception was granted if the airspeed source was under personal individual control, such as a window in a private office, or a desk fan, but only above 26 ºC (79ºF).