Active solar retrofit of a residential house, a case study in Egypt

There are extraordinary opportunities to reduce the consumption of fossil energy in retrofitting existing buildings in Egypt. For instance, South Tahrir (150km northwest of Cairo) falls in the arid climate zone with an annual-average daily global irradiation value of 23.76 MJ/m2 and for diffuse irradiation they are 9.65 MJ/m2 for Cairo and approximately 3300 hours of full sunshine. However, in extreme climates like Egypt, conditions show relatively high demand for cooling and heating energy.
To overcome this problem and to examine these opportunities, this study evaluated the active solar retrofit of a passive house built in South Tahrir city. The aim of the study was to investigate the potential of active solar retrofits. The building performance was evaluated using TRNSYS, and monitored during two years of occupancy (2004-2006) to evaluate the performance and energy/carbon emissions reduction. The research took into consideration active design strategies such as solar thermal domestic water heating, photovoltaic panels and solar thermal air conditioning. First, the performance of the passive house before and after the retrofit was represented and compared. The house thermal and electric loads were compared to the solar thermal and electric production. Then results were evaluated to assess the suitability of each strategy based on energy performance. The final result of this study proved theoretically the feasibility of installing solar hot water collectors and solar thermal air conditioning. For this specific location and climate conditions an active solar retrofit of the residential house is energetically rewarding. Future solutions should address all of the thermal loads (cooling, heating, DHW) with thermal energy collection and only the electric loads (internal loads and auxiliary components) with photovoltaic collection. However, as long as the prices of electricity are highly subsidized the active solar retrofit is still considered not be cost effective.