Towards Green Palestinian Cities the Feasibility of Using Roof Gardens in Nablus as a Case Study

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Mallah, Dua "Mohamad Rayeq" Ahmad
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An-Najah National University
Urban greening is considered to be a very important issue in many cities, just like the city of Nablus where the topography and the political situation restrict the establishment of new green spaces. In this study, the feasibility of green roofs in the city of Nablus was tested, after displaying the background of green roofs and the benefits could be provided by green roofs, and how cities encourage the application of green roofs to take advantage of these benefits. Then the physical and environmental profile of the city was clarified, to determine if the city's buildings could accommodate green roofs, after studying the common construction method in the city and the building structure it is clear that the city existing buildings can sustain extra load added by the lighter types of green roof without structural reinforcement. Also the added cost of the green roof was calculated to be 37.5%. After exploring the city's buildings ability to sustain green roofs and the availability of construction materials, the citizens knowledge regarding green roofs and their willingness to apply green roofs to their building was measured by qualitative and quantitative approach, questionnaire results shows that the participants were willing to add green roofs to their buildings but have concerns over the cost of green roofs, further more the participants linked the benefits of green roofs with the benefits provided by plants and green areas in general, but not to the reduction of energy used in heating and cooling, or reducing urban heat. So in the last part of this research calculation of the actual reduction of direct solar radiation on the roof was conducted using Ecotect, About 50% reduction on the total all year direct solar radiation in the villa and 62% reduction is achieved in the multi storey building, also reduction in the energy used for cooling and heating was also calculated. The Ecotect results indicate that insulated green roof have the lowest energy consumption rate, reducing approximately 10% for the villa total year consumption and 18% for multi storey building. Where green roof provide about 9% and 17% reduction for the villa and multi storey building. Thermal computation resulting from different U-value, calculations showed total saving up to 26% of total energy consumption by green roof, and 37% by adding insulation to the green roof layers. These results show that green roofs can be cost effective on the long term as the increase of building construction cost is to be returned in the reduction of energy loads.