Correlation between retrofitting building evenlope and thermal improvement on social housing in hot-arid climate

The work examines the correlation between insulation retrofitting technique combined with the night purge ventilation and indoor thermal improvement within hot-arid climate. The chosen case study is an existing prototype residential building for a social housing project that consists of 500 thousand unit and was built during the period from 2005 to 2011 in October 6th city in Greater Cairo. The study used IES software to simulate the application of the combined strategy of external insulation (from local material) and night purge ventilation to examine their effect on improving indoor thermal comfort comparing to the base case. The simulation was conducted in all seasons (winter, summer, spring and autumn) throughout the whole year months. Results revealed that this combined strategy is not effective in winter period as it has made an improvement of 4.4% from the base case and 5.5% when applying external insulation only. Furthermore, this combined strategy was significantly effective in summer period as it has improved indoor thermal comfort by 58.3% from the base case and by 10.2% when applying external insulation only. Additionally, the strategy was not effective during spring-autumn period as it made an improvement of only 6.0% in indoor thermal comfort comparing to the base case and of 1.9% when applying external insulation only. According to these results, the study confirms that unlike the external insulation, the night purge ventilation as a user behavioral strategy had the major impact on indoor thermal improvement (48.1 % comparing to the base case) during summer for this kind of buildings in hot-arid climate.