Transient modelling of heat fluxes and temperatures in structures was conducted to examine the effect of various characteristics on the temperature response during unusual operating and extreme weather conditions. The analytical model was validated using published experimental data and numerical results from well-known computer codes. The effect of including radiation heat transfer between interior surfaces, using the Mean Radiative Temperature method, on the temperature response was investigated and found to be negligible for a typical commercial building and a house during winter and summer power outages. The effect of thermal mass in the interior and exterior walls on the inside temperature drift after an HVAC system cutoff or a power outage was presented. The inside air temperature response curve is presented for different wall (exterior or interior) constructions of buildings. The effect of insulation position in exterior walls was also shown for several R values. The effect of exterior wall emissivity, sky temperature, outside vertical convective coefficient, furnishings, and ground temperature on the interior temperature response during winter and summer power outages were examined for buildings. The effect of infiltration on the temperature drift in buildings was investigated during winter and summer power outages. Restarting the HVAC after the power outage was examined during both seasons for typical buildings. Outside temperature profiles exceeding the 97.5 design temperature criterion were used to study the effect of extreme weather on the interior temperature of buildings with the HVAC system operating. / Ph. D.