Assessment of the potential of establishing extensive green roofs at the American University of Beirut

Abstract

Beirut is home for one fourth of the Lebanese population estimated at 4 million (2011), yet the city suffers from a severe lack of green areas and open spaces. Exploring the use of building walls and roofs as surfaces for plants is one possible direction that would contribute to healthier urban environments. This study aimed at exploring the possible role that the America University of Beirut can play to promote green roofs by contributing to knowledge and acting as a successful show case for extensive green roofs for the neighborhood and the country. Desk Research on green roofs in university campuses was performed as a bench mark exercise to determine the role of universities in promoting green roofs. Field visits and assessment of AUB buildings and green areas using GIS applications allowed for the determination of potential areas and their impact on campus greening. A review of floras and published theses was conducted to identify potential native coastal plant species suitable for use as extensive roof vegetation. The findings highlighted the important role that universities have been playing in promoting green roof research with many establishing prototypes on their campuses. An assessment of AUB revealed that the campus currently has 27 percent open green spaces, and that with the introduction of extensive green roofs this value can be increased to 34.5 percent. The implementation of green roofs on campus however is currently hindered by the absence of documentation regarding structural analysis and loading capacity of almost all building roofs. A horticultural review of 84 native coastal plant species based on plant height, succulence, resistance to salt and drought and flower show led to the selection of 12 herbaceous plants species including 4 annuals and 8 perennials that were recommended for testing under extensive green roof conditions.