describe a four-step method to analyze energy performance of residential buildings with the intention of detecting building opportunities for energy improvement. The method can help to identify if a building is a good candidate for hot-water heater retrofit, programmable thermostat installation, envelope improvement or highefficiency HVAC equipment retrofit. In the first step of the method, energy signature models are obtained by regressing the energy consumption from utility bills to actual average daily temperatures.Two regression equations of the form of Eq. (2)