Green roofs under hot and dry climate in south-west of Algeria: Study of the implementation conditions

Abstract

The Algerian Sahara occupies over 80% of the Algerian surface. Green roofs and facades will contribute to transforming the desert into ecological green cities. This work addresses the possibility of realization ofing such green buildings under the climatic conditions of the Saharan cities of Algeria by highlighting the need for gray water irrigation in order to overcome the water problem in these arid regions. A collection of different native and non-native plants that can be planted in hot arid climate by carrying out bibliographic research on their applications in other regions and climates is presented. Carpobrotus acinaciformis is the most recommended, among the succulent species plants, for its great success in the study area. Regarding herbaceous plants, the basil, rosemaryand canna are best adapted to the harsh climatic conditions. A chemical analysis of grey-water was conducted to examine the feasibility of reusing generated water from domestic activities. The results show that slaked lime can be added to purify water, and filtration on sand is recommended. Furthermore, simulations were carried out using TRNSYS to analyze the cooling effect of green roofs and facades compared to conventional roofs. The results show that green roofs help significantly in decreasing the number of hours of discomfort and the cooling energy use compared to the green facades.