Impact of green roof in building energy performance: experimental and numerical study

Abstract

Green roofs are considered an effective solution in contributing to the resolution of several environmental problems at building and urban levels. The present paper provides a numerical and experimental study of the impact of a green roof on energy performance of a building. A model of green roof thermal behavior was coupled with a building thermal code which permitted the evaluation of green roof foliage and soil surface temperatures. The model was experimentally validated according to green roof platform which was elaborated. It consists of 5 buildings, than 4 street canyons where 2 buildings were covered with various vegetated elements. Roof support surface temperature was evaluated, a reduction of the maximum temperature by 30 °C was found in the summer due to the green roof. The impact of the green roof on thermal comfort, cooling and heating demand was evaluated. With a green roof, summer indoor air temperature was decreased by 2 °C and annual energy demand was reduced by 6 %. Finally, the results found in this study lead us to better understand the influence of green roofs on the building thermal behavior.