Data from a Residential Energy Study (RES) were used to examine the weather sensitivity of various household appliances located in households within the Sydney metropolitan area. Thermal environmental indices effective temperature (ET*), standard effective temperature (SET*) and simple air temperature degree-days were used to quantify the dependence of household appliance energy consumption on outdoor weather. Specific appliances included: room air-conditioners, room heaters, refrigerators, freezers and domestic hot-water systems, all of which exhibited some degree of weather sensitivity, particularly space heating and cooling devices. Probit regression techniques were used to predict the degree-day values at which households tend to switch on 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 temperature of 18 degreesC was the most appropriate base temperature for calculation of both heating and cooling degree-days. (C) 2003 Published by Elsevier B.V.