Construction and design requirements of green buildings’ roofs in Saudi Arabia depending on thermal conductivity principle

Abstract

Green buildings aim to promote the positive role of buildings in the community service, and to reduce the negative impact of buildings on the natural environment, as well as to support the national economy. This research showed the inefficiency of conventional roofs, especially those of residential buildings, against heat transfer at different geographical zones of KSA – Kingdom of Saudi Arabia. Thermal analysis of different computational models also led to improvements reached to 89% on roof performance regarding its thermal insulation. These improvements were obtained by converting those conventional concrete roofs into green roofs. In this study, details of several scenarios were shown, and analytical calculations were conducted for different types of green roofs compared to conventional roofs in two main cases, air absence and air presence inside it. According to these scenarios, the impact of vegetation cover on the building roof was determined using thermal models of roof slab in two sub-cases of vegetation cover, one when using the turfing and second when using the shrubs. The results showed that the use of turfing as a vegetation cover is insufficient at all thermal climatic zones of KSA, and the use of air spaces technique increased the efficiency of turfing-solid roof by 87% compared to conventional-solid roof. The use of shrubs in addition to air spaces technique increased the efficiency to acceptable level at most thermal climatic zones. The results also led to recommendations to use a manufactured thermal insulation layer, in addition to shrubs and air spaces, at the first thermal climatic zone of KSA.