Air-conditioning usage behaviour of the elderly in caring home during the extremely hot summer period: An evidence in Chongqing

Using air conditioners to cool down the indoor thermal environment is necessary to avoid the elderly exposing themselves to hot conditions in extreme weather. Considering the frequency occurrence of heatwave events, this study investigated air-conditioner operation behaviours and indoor thermal condition features during extremely hot summer periods to understand the elderly's thermal demand and their behaviour patterns of using air conditioners. Fifteen elderly residents from a caring home in Chongqing were recruited, and their air-conditioners’ historical operation data and indoor and outdoor temperatures were continuously measured and retrieved from the air-conditioner manufacturing data warehouse. The results indicate that the elderly subjects were active in adjusting their air-conditioner settings with multiple daily actions of turning-on and setpoint-changing behaviours in the extremely hot summer period. The air-conditioner temperature setpoint preferred by the elderly subjects was between 27 °C and 30 °C, resulting in the indoor temperature mainly remaining in the range between 28 °C and 32 °C, which presented a negative relationship with the outdoor temperature. The elderly's daily air-conditioner operation in the extremely hot summer period can be clustered into four groups, including inactive-usage, afternoon-usage, night-usage and all-day-usage groups. The inactive usage group with short-term and discrete air-conditioner operation would prefer a fast-cooling setting, whereas the all-day usage group showed a higher setpoint-change frequency, indicating the dynamic cooling demand may exist in the elderly's long-term air-conditioner daily usage.