DEVELOPMENT OF GREEN ROOFS INSTALLATION GUIDELINE FOR RESIDENTIAL BUILDINGS OF DHAKA CITY

Abstract

The use of green roofs compensates the diminishing essential ground spaces in Dhaka city. Green roofs significantly reduce urban heat island effect, save energy, manage storm water, improve air quality, and create food sources; thus, creating a healthy environment. Various research studies have found different typologies of green roofs along with components, watering and drainage systems. However, only about 12% of households in Dhaka city use green roofs, and the construction and maintenance of green roofs require a wide range of professionals. This thesis aims at developing a set of guidelines with a multidisciplinary approach, which has not yet been included in green roof research due to limited use and popularity in Bangladesh. The first phase of the study analyses different existing research on green roofs to develop parameters for the selection of case studies and subsequent field surveys. The findings are tabulated in the form of charts and diagrams in order to define the parameters instrumental for analyzing the data collected from field surveys and questionnaires. Finally, the analyzed data are synthesized in order to develop a set of multidisciplinary guidelines to install and maintain green roofs in the context of Dhaka city. The synthesized data is not a rigid set of instructions, rather guidelines based on availability of materials, knowledge of local professionals, conditions of climate, practicality of maintenance and user-friendliness in green roof constructions. The guidelines cater to the parameters of waterproofing, insulation, protection, drainage material, filter, substrate and plants among the general components of green roof constructions. The guidelines also include further recommendations about watering methods and drainage systems for each typology of green roof identified from literature studies and surveys. In conclusion, the study identifies why “extensive with designed intensive plantation” is the most popular type of green roof when two other types, namely “extensive” and “intensive”, have also been broadly identified in the studies regarding the typologies of green roofs. The study establishes a final set of recommendations regarding coordination among professionals, use of lightweight green roof, parapet treatment, overflow drainage, soil mix ratio, plant structure selection, plants and urban farming, and cost.