Field study on the use of air conditioners in Beijing residences

Heating and cooling loads in residential buildings are determined not only by outdoor environment and internal heat gains, but also by the use of air conditioners. The usage includes the operation pattern of air conditioner and the two set points of room air temperature. One set point is the lower temperature limit for air conditioner to start up; the other set point is the upper temperature limit of the comfortable zone with air-conditioning. This paper presents the investigation results of the use of air conditioners in 42 air-conditioned residential units in Beijing.. It is found that air conditioners are usually used intermittently in residential units. Occupants perceive the warmth as being less serve in non-air-conditioned environment than in air-conditioned environment. For most of occupants, they start their air-conditioners under the condition of air temperature above 29 degrees C, while they will not be satisfied with the temperature condition above 26 degrees C in air-conditioned environment.