Abstract Cool roofs save energy and are particularly suited for low rise buildings in hot climates. This paper presents results of potential energy savings for existing houses in two islands (Sicily and Jamaica) based on validated thermal models. It also presents the lifecycle environmental impact of the cool paint focussing on both the midpoint and endpoint impact categories and compares these with thermal insulation impact. It was found that significant net energy benefits are possible in both locations by a cool roof, more pronounced in Jamaica, which has no heating demand; savings are comparable with thermal insulation reductions. The environmental impact of cool paint is lower than a variety of thermal insulation materials with the exception of water depletion potential. The main hotspots of the cool paint are the production of the polymer followed by the production of the pigment.