Thermal comfort in an office with intermittent air-conditioning operation

An effective way to reduce A/C energy use is to switch off air conditioning during unoccupied periods. The main concern is, however, whether occupants' thermal comfort is sacrificed. This paper reports a study of the impacts of switching off A/C during unoccupied hours in an office on thermal comfort of occupant after returning to office and resuming the operation of A/C system. Site measurements for both indoor thermal environmental parameters and energy consumption of A/C were carried out and the thermal comfort of occupants was assessed. Measurement and assessment results indicated that up to 11% of annual energy consumption of A/C for the office could be saved, but the level of thermal comfort of occupants was not greatly degraded. Practical applications: Intermittent operation of A/C is often ignored when people talk about energy saving. It requires no additional cost and equipment, but the saving is significant. Moreover, no advanced technology or knowledge is required. The most important result is that thermal comfort level is not scarified during occupied hours.