This study analysed over 1.8 million measurements of air conditioner power consumption and indoor/outdoor air temperatures in 129 houses in Adelaide, Brisbane and Melbourne from 2012 to 2014. It was found that the preferred indoor air temperature range, at which occupants are most unlikely to operate air conditioners, increases for warmer local climates. In each city, the air conditioner switch on and off indoor temperatures, and the indoor temperatures when air conditioner is in operation can be grouped into three prevailing outdoor temperature ranges: the low range, the shoulder range and the high range. Occupants are not very tolerant at the low and high temperature ranges, while they are more adaptive with the shoulder temperature range. This finding supports the simplified static thermostat setting approach used in the AccuRate software for house energy rating, though the existing thermostat settings should be adjusted with more research in understanding thermal comfort and air conditioner operation behaviours in residential houses.