Effects of rooftop vegetation using artificial substrates on the urban climate and the thermal load of buildings

Urban greening to cool towns and cities: A systematic review of the empirical evidence

“…These studies were more supportive of surface temperature of green roofs being cooler than non-green roofs (Wong et al, 2003;Alexandri and Jones, 2007;Wong et al, 2007) or at least less variable (Köhler et al, 2002). However, the temperature difference can depend on the time of day or month of the year (Harazono et al, 1991;Takebayashi and Moriyama, 2007).…”

“…Studies have compared temperature on or above sections of a roof with vegetation, with sections of a roof (usually the same roof) without vegetation and therefore addressed the local effects of green roofs. The findings have been mixed, with some evidence of lower air temperatures above green sections in some studies (Harazono et al, 1991;Wong et al, 2003), but not in others (Alexandri and Jones, 2007;Wong et al, 2007). These studies were more supportive of surface temperature of green roofs being cooler than non-green roofs (Wong et al, 2003;Alexandri and Jones, 2007;Wong et al, 2007) or at least less variable (Köhler et al, 2002).…”

Influence of vegetation damage on urban cooling effects

“…Onmura et al (2001) demonstrated a 50% reduction in heat flux into a room underneath a roof lawn garden compared to a concrete slab roof in Osaka in summer. Air temperature in a room below a well-irrigated intensive green roof was 2 C cooler than under a control roof (Harazono et al, 1990(Harazono et al, / 1991. These studies, by revealing relative cooling differences between green and conventional roofs, give an indication of the potential increase in downward heat flux on green roofs when the vegetation is damaged and areas of bare soil substrate are revealed.…”

Climate change in urban areas. Part 2, Measures

“…So sind die spezi fischen Heizenergieverbräuche zum Beispiel in Deutschland gegen wärtig noch viel zu hoch, da ein großer Teil der über wiegend alten Bausubstanz, so auch im Ruhrgebiet Dadurch erhöht sich die Raumtemperatur des Gebäudes mit "Betondach" um 23 K gegenüber der des Gebäudes mit "Gründach" [21]. Sollte diese Temperatur differenz beispielsweise durch eine elektrisch betriebene Klimaanlage ausgeglichen werden, wäre hierzu ein erheblicher Energieaufwand notwendig.…”