Thermal Comfort and Cultural Values: Developing an Integrated Methodology for Energy Efficient Retrofitting of Built Heritage in Hot Dry Climates with the case of Cairo

Climate change threatens not only the present and the future, but also the past through its impact on the built heritage. This challenging predicament calls for urgent reduction of energy usage within built environments that are responsible for a large percentage of global energy consumption and carbon dioxide (CO2) emissions. The energy consumption of the built environment needs to improve by 2030 to meet global climate goals. Therefore, conserving and rehabilitating built heritage is considered a part of Sustainable Development Goals (SDG) identified by the United Nations to ensure a better sustainable future and conserve people’s identity and culture at the same time. Heritage sites are considered physical legacies of civilizations across the world; this is why, con-serving heritage sites and buildings has become one of the primary policies pursued across the world to preserve cities’ identities. However, retrofitting heritage buildings for energy efficiency is not always easy where cultural values are highly regarded. Enhancing their energy performance became an urgent need to face climate change effects due to rapid energy consumption. Additionally, attempts to reduce energy consumption usually are linked to thermal comfort improvements. Since improving energy in heritage buildings can affect heritage values, these buildings were often excluded from energy improvements, but this has recently been changing. Many retrofitting initiatives in built heritage are being carried out in colder, European zones, while in the Middle East and North Africa (MENA) region – a hot zone - is behind in this field. In North Africa, achieving thermal comfort in buildings has currently become an urgent need due to excessive demand in energy consumption, especially with the change of climate conditions for the last 30 years that lead to depending more on energy for ventilation and cooling systems. While for heritage buildings, more specifically, improving thermal comfort and energy require a multidisciplinary approach concerned with both conserving values and occupants’ well-being.Therefore, this PhD research aims at developing a retrofitting methodology which balances heritage, thermal comfort, and energy targets in heritage residential buildings in hot dry climate. Thus, this study discusses how heritage residential building stock in hot dry climates can be made more efficient in their energy performance without affecting their heritage values. To achieve this goal, the study develops an energy retrofitting methodology which is mainly based on in-depth investigation of selected buildings. To validate this developed methodology, it is applied to heritage residential building stock located in Downtown Cairo, Egypt, which acts as a case study for expanding this concept to similar building stock in North Africa. The results show that indoor thermal comfort and energy use can be improved by applying the proposed integrated methodology in the heritage residential building stock in hot climates. By applying this methodology in Khedivial Cairo, a part of Downtown Cairo, high indoor comfort with approximately zero-energy performance use can be achieved for 133 heritage residential buildings— representing (50.7 %) of the total buildings volume of Khedivial Cairo area. Furthermore, this methodology would cover the maximum needed energy by using generated solar energy and export the surplus (if any) to energy grids. More importantly, this methodology would improve the indoor thermal comfort and is highly compatible with the Egyptian Energy Code requirements and cultural values of the different building heritage grades. The proposed methodology will contribute to support decision-makers in processes of retrofitting built-heritage through providing the most suitable retrofitting scenarios in relation to energy efficiency and conservation.Doctorat en Art de bâtir et urbanisme (Polytechnique)