The impact from using cool roof coatings on the cooling and heating loads and the indoor thermal comfort conditions of residential buildings for various climatic conditions is estimated. The energy cooling loads and peak cooling demands are estimated for different values of roof solar reflectance and roof U-value. The results show that increasing the roof solar reflectance reduces cooling loads by 18-93% and peak cooling demand in air-conditioned buildings by 11-27%. The indoor thermal comfort conditions were improved by decreasing the hours of discomfort by 9-100% and the maximum temperatures in non air-conditioned residential buildings by 1.2-3.3 degrees C. These reductions were found to be more important for poorly or non-insulated buildings. For the locations studied, the heating penalty (0.2-17 kWh/m(2) year) was less important than the cooling load reduction (9-48 kWh/m(2) year). The application of cool roof coatings is an effective, minimal cost and easy to use technique that contributes to the energy efficiency and the thermal comfort of buildings. (C) 2007 Elsevier B.V. All rights reserved.