Impact and potential of community scale low-energy retrofit: case study in Cairo

There are extraordinary opportunities to reduce the consumption of fossil energy as a result of retrofitting the existing buildings in Egypt. For instance, Cairo falls in the arid climate zone with an annual total radiation above 2409 bankable kWh/m2 per annum with approximately 3300 hours of full sunshine. However, the poorly insulated fabric of most buildings shows relatively high demand for cooling and heating energy. To overcome this problem and to examine these opportunities, this study evaluates the retrofit of a middle-income urban residential case in Cairo. The aim of the study is to investigate the potential and impact of retrofits on two different scales. The first is on the building scale, intending to reach a low-energy performance. The second is on a community scale, intending to increase the dependence on renewable sources. The case study employed TRNSYS to evaluate the performance and energy/carbon emissions savings. The research took in consideration passive and active design strategies such as envelope retrofit, internal loads reduction, and natural ventilation; in addition to domestic water heating, photovoltaic panels and solar thermal air conditioning. The results were evaluated to assess the suitability of each strategy based on energy performance. The final result of this study shows the feasibility of improving the envelope performance and installing solar hot water collectors and solar thermal air conditioning. The low-energy retrofit for old residential buildings leads to significant savings in energy consumption when applied on community scale rather than building scale. However, it is urgent to set energy conservation and code-enforced retrofit measures to start a national retrofit process.