The first regression coefficient is a measure of the base load or load independent of weather conditions (outdoor temperature is equal to the balance point temperature), and the second regression coefficient is a measure of the impact of the outdoor temperature on the energy consumption (the balance point temperature is constant). Accuracy of the method was satisfactory for the sample of houses used in the investigation, allowing identification of high hot water temperature setpoint, low efficiency hot water heaters, no nighttime set-backs,high rate of infiltration, and low furnace efficiency.