Investigating energy savings due to implementing green roof on existing residential buildings in UAE

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The British University in Dubai (BUiD)
In recent years, building energy consumption keeps rising due to growth in population, increasing demand for comfort in indoor environment and global climate changing. The contribution from buildings toward global energy consumption is approximately 40% mostly from heating, ventilation and air conditioning (HVAC) systems. Fossil fuels are the main source for electricity production however they are finite reserves. Reducing fossil fuel dependency in the built environment is required and necessitates drastic reactions amongst this issue. Building refurbishment is one of the critical aspects that lowers the dependency on fossil fuels and mitigates the future energy crisis. Green roof has been used on building roofs since ancient times. A widespread use of roof vegetation as a refurbishing technique has significantly increased in recent years. The specific purposes of green roof installations vary, between storm water reduction and/or improved building energy efficiency and often both. As energy efficiency concerns; green roofs have been introduced as a viable and effective method for reducing building electrical consumption. The main purpose of this study is to investigate the potential saving due to green roof as a refurbishment technique on residential houses in UAE. Dual based research method (calculations and Simulation) was conducted on a multi-story family house. Heat flux through the green roof was examined to calculate the conduction gains. House model was constructed in IES-VE energy software to calculate the cooling load due to green roof and compared it to bare roof cooling load. The green roof model was altered to study the impact of the metrological conditions, soil substrate thickness, leaf area index, and soil water content on the thermal performance of the assembly. The results of this dissertation showed that, promising energy savings potential are offered by implementing green roof as retrofitting method in UAE. The evaporative cooling effect and the insulation offered by soil substrate were always being able to reduce the conduction gain thus cooling load. The assembly lowered the cooling load by 6% and 12% in winter and summer, respectively. The researcher found that, the optimum energy reduction was obtained because of the evaporative cooling effect of canopy evapotranspiration phenomenon and the insulation provided by the soil substrate. The evaporative cooling phenomenon was able to reduce the cooling load by 7.3% comparing to bare roof building. The insulation effect of the soil substrate however, was able to reduce the cooling load by 7.7%.
energy saving, green roof, residential buildings, United Arab Emirates (UAE), energy consumption, global climate change