Mitigating the Heat Island Effect: Green Roofs at Duke University

In exchange for flourishing cities built upwards, urban communities have sacrificed permeable and moist surface areas for impervious surfaces (buildings, pavements) and as a result, cities experience warmer climates than surrounding rural areas. This phenomenon is referred to as the Urban Heat Island Effect. Both domestically and internationally, cities have utilized cool pavements, increased tree cover and vegetation, green and heat-deflecting roofs to counteract the heat island effect. Planting vegetated cover on the roofs of city buildings is the ideal method because it simultaneously mitigates the heat island effect, reduces energy bills and improves building aesthetics. This study focuses on the potential application of green roofs in two older academic buildings on Duke University’s campus in Durham, North Carolina. Dynamic modeling results through eQuest show green roofs have much higher net present values (NPVs) for both buildings by significantly reducing both operating and energy costs. Moreover, the difference in NPVs is large enough to warrant installing them before the old conventional roof requires replacement