Temperature decreases in an urban canyon due to green walls and green roofs in diverse climates

This paper discusses the thermal effect of covering the building envelope with vegetation on the microclimate in the built environment, for various climates and urban canyon geometries. A two-dimensional, prognostic, micro scale model has been used, developed for the purposes of this study. The climatic characteristics of nine cities, three urban canyon geometries, two canyon orientations and two wind directions are examined. The thermal effect of green roofs and green walls on the built environment is examined in both inside the canyon and at roof level. The effects of this temperature decrease on outdoors thermal comfort and energy savings are examined. Conclusions are drawn on whether plants on the building envelope can be used to tackle the heat island effect, depending on all these parameters taken into consideration. (c) 2006 Elsevier Ltd. All rights reserved.