Heating and cooling of residential and commercial buildings account for approximately 40 percent of
world's total energy consumption [1]. This considerable amount of energy consumption have made
scientist to search for every possible way to reduce it. Among the most effective approaches is the use of
green roof for buildings. Although the positive effects of using such roofs are well proven, the amount of
energy reduction which can be achieved by this method is another issue that this paper is trying to
investigate. In this study, three different climates of Iran are chosen for the analysis. The results
demonstrate that using green roof in Very Hot Dry (Bandar Abbas), Warm Dry (Isfahan), and Mixed Dry
(Tabriz) climates causes energy consumption to decrease by approximately 8.5, 9.2 and 6.6 percent,
respectively. Considering the reduction of energy consumption as the only desirable benefit of green roof,
the payback period would be 25e57 years (depending on the climate).