Reducing the acoustical façade load from road traffic with green roofs

Noise annoyance by road traffic is a major issue in urbanized regions. In this study, the influence of a green roof on the façade noise load was investigated numerically for road traffic at close distance. Consistent positive effects of the presence of a green roof are observed at non-directly exposed (parts of) façades. A sufficient green roof area is needed to obtain significant reductions in total A-weighted road traffic noise level. With increasing traffic speed, the green roof effect increases for light vehicles. In case of heavy vehicles, this dependence is less strong. In a street canyon situation, the façade load in the non-exposed canyon is largely influenced by both the roof slope and the presence of a green roof. A flat roof generally results in the best average shielding. A green roof is especially interesting in case of a saddle-backed roof. With a good choice of green roof parameters, the shielding of a flat green roof can be approached.