Date of Defense
27-6-2026 9:30 AM
Location
F1-1124
Document Type
Thesis Defense
Degree Name
Master of Science in Architectural Engineering
College
COE
Department
Architectural Engineering
First Advisor
Dr. Mohamed Mahgoub
Abstract
The climate of the United Arab Emirates (UAE) is characterized by extreme hot-arid conditions, with prolonged summers, intense solar radiation, and elevated temperatures. This significantly increases the building's cooling demand. Due to the UAE's reliance on fossil fuels for electricity generation, reducing energy consumption in buildings is recognized as a strategic objective aligned with the UAE Vision for Sustainability. Roofs represent an essential element of a building's envelope, significantly influencing thermal absorption, particularly in low-rise villas featuring exposed flat concrete slabs. Consequently, roofing strategies such as cool and green roofs serve as a viable passive method to reduce cooling loads and enhance indoor thermal comfort within a building. Despite their widespread application, few studies has been conducted to assess their performance in the extreme climatic conditions of Al Ain.
This study aims to assess the differences in thermal and energy performance between cool and green roofs in a typical residential villa in Al Ain City. DesignBuilder was utilized to apply a quantitative simulation-based approach. The selected case study is a two-story detached villa that represents the architectural practices in the region. To ensure the accuracy of the simulated model, the base model was calibrated against actual data of monthly electricity consumption. The validation results revealed a strong Pearson correlation coefficient (R = 0.956) and a Root Mean Square Error (RMSE) of 20%, consistent with ASHRAE Guideline 14 which indicates that the model is strong and viable.
Six scenarios were evaluated: Base case, increased insulation thickness, cool roof, cool roof with air gap, green roof, and green roof with air gap. To isolate the effect of roof modification, all other factor were held constant including HVAC settings, occupancy schedules, and internal gains. The performance indicators in the study are roof surface temperature, indoor operating temperature, annual energy usage, and carbon emissions.
Results demonstrate that roof surface properties strongly affect the thermal performance of the building. When compared to a conventional roof under peak summer conditions, the cool roof decreased the roof surface temperature by approx. 26–28°C (40–45%). The green roof reduced surface temperatures moderately and provided a greater daytime thermal storage effect. In terms of energy efficiency, the green roof saved 4.6% while the cool roof saved the most electricity annually (6.6%, or roughly 293 kWh). The increased insulation thickness and the addition of 50 mm air gap in both cool and green roof produced negligible improvements. Similar trends were observed in the carbon emissions results.
In summary, both strategies tend to reduce energy consumption and enhance thermal conditions in Al Ain's hot, arid climate. However, the cool roof is more efficient in reducing cooling demand and carbon emissions. The findings offer evidence-based recommendations for sustainable roof strategies in UAE's residential buildings.
Included in
A COMPARATIVE STUDY OF GREEN AND COOL ROOF STRATEGIES IN ENERGY SAVING AND THERMAL PERFORMANCE IN THE HOT-ARID CLIMATE OF UAE
F1-1124
The climate of the United Arab Emirates (UAE) is characterized by extreme hot-arid conditions, with prolonged summers, intense solar radiation, and elevated temperatures. This significantly increases the building's cooling demand. Due to the UAE's reliance on fossil fuels for electricity generation, reducing energy consumption in buildings is recognized as a strategic objective aligned with the UAE Vision for Sustainability. Roofs represent an essential element of a building's envelope, significantly influencing thermal absorption, particularly in low-rise villas featuring exposed flat concrete slabs. Consequently, roofing strategies such as cool and green roofs serve as a viable passive method to reduce cooling loads and enhance indoor thermal comfort within a building. Despite their widespread application, few studies has been conducted to assess their performance in the extreme climatic conditions of Al Ain.
This study aims to assess the differences in thermal and energy performance between cool and green roofs in a typical residential villa in Al Ain City. DesignBuilder was utilized to apply a quantitative simulation-based approach. The selected case study is a two-story detached villa that represents the architectural practices in the region. To ensure the accuracy of the simulated model, the base model was calibrated against actual data of monthly electricity consumption. The validation results revealed a strong Pearson correlation coefficient (R = 0.956) and a Root Mean Square Error (RMSE) of 20%, consistent with ASHRAE Guideline 14 which indicates that the model is strong and viable.
Six scenarios were evaluated: Base case, increased insulation thickness, cool roof, cool roof with air gap, green roof, and green roof with air gap. To isolate the effect of roof modification, all other factor were held constant including HVAC settings, occupancy schedules, and internal gains. The performance indicators in the study are roof surface temperature, indoor operating temperature, annual energy usage, and carbon emissions.
Results demonstrate that roof surface properties strongly affect the thermal performance of the building. When compared to a conventional roof under peak summer conditions, the cool roof decreased the roof surface temperature by approx. 26–28°C (40–45%). The green roof reduced surface temperatures moderately and provided a greater daytime thermal storage effect. In terms of energy efficiency, the green roof saved 4.6% while the cool roof saved the most electricity annually (6.6%, or roughly 293 kWh). The increased insulation thickness and the addition of 50 mm air gap in both cool and green roof produced negligible improvements. Similar trends were observed in the carbon emissions results.
In summary, both strategies tend to reduce energy consumption and enhance thermal conditions in Al Ain's hot, arid climate. However, the cool roof is more efficient in reducing cooling demand and carbon emissions. The findings offer evidence-based recommendations for sustainable roof strategies in UAE's residential buildings.