This paper uses data from a Residential Energy Study (RES) to examine the weather sensitivity of various appliances located in households within the Sydney metropolitan area. Plug-loads of up to seven separate electrical appliances in each of 136 households were logged at 30-minute intervals for 18 months. Specific electrical appliances analysed in this paper include room air-conditioners, room heaters, refrigerators, freezers and domestic hot water systems. Climate indices effective temperature (ET*) and standard effective temperature (SET) were calculated separately for the coastal and inland climate zones within the Sydney metropolitan area. These indices, along with simple air temperature, were converted into degree-day values and used to quantify the dependence of household appliance energy consumption on outdoor weather. Regular linear and polynomial regression models of daily total appliance energy consumption were fitted to the various degree-day indices. The strength of the statistical association or explained variance quantified the extent of weather sensitivity across the sample of households. Probit regression techniques were used to identify the thermal environmental thresholds at which households tend to switch on their heating and cooling appliances.

All appliances demonstrated weather sensitivity to varying degrees, and this was universally stronger during the cooling season (summer) than during the heating season (winter). The outdoor SET version of the degree-day index demonstrated a stronger statistical association with space cooling energy consumption than conventional air temperature degree-days. The mean daily temperature associated with minimum heating and cooling energy consumption for Sydney indicated that a degree-day base temperature of 18°C was the most appropriate base temperature for the calculation of both heating and cooling degree-days. This finding is among the first empirical supports for adopting a constant year-round base temperature in degree-day calculations in Sydney.