In recent years, roof-spraying and rooftop lawns haveproven effective on roofs with poor thermal insulation.However, the roofs of most buildings have insulatingmaterial to provide thermal insulation during thewinter. The effects of insulation has not previouslybeen quantified.In this study, the authors collected measurements of aninsulated building to quantify the thermal effects ofroof-spraying and rooftop lawns. Roof-spraying didnot significantly reduce cooling loads and requiredsignificant amounts of water. The conclusion is thatroof spraying is not suitable for buildings with well-insulated roofs. Rooftop lawns, however, significantlystabilized the indoor temperature while additionallyhelping to mitigate the heat island phenomenon.