Towards Nearly-Zero Energy in Heritage Residential Buildings Retrofitting in Hot, Dry Climates

Retrofitting “nearly-zero energy” heritage buildings has always been controversial, dueto the usual association of the “nearly-zero energy” target with high energy performance and theutilization of renewable energy sources in highly regarded cultural values of heritage buildings.This paper aims to evaluate the potential of turning heritage building stock into a “nearly-zeroenergy” in hot, dry climates, which has been addressed in only a few studies. Therefore, a fourphaseintegrated energy retrofitting methodology was proposed and applied to a sample of heritageresidential building stock in Egypt along with microscale analysis on buildings. Three referencebuildings were selected, representing the most dominant building typologies. The study combinesfield measurements and observations with energy simulations. In addition, simulation models werecreated and calibrated based on monitored data in the reference buildings. The results show that theapplication of hybrid passive and active non-energy generating scenarios significantly impacts energyuse in the reference buildings, e.g. where 66.4% of annual electricity use can be saved. Moreover,the application of solar energy sources approximately covers the energy demand in the referencebuildings, e.g. where an annual self-consumption of electricity up to 78% and surplus electricityup to 20.4% can be achieved by using photo-voltaic modules. Furthermore, annual natural gas ofup to 66.8% can be saved by using two unglazed solar collectors. Lastly, achieving “nearly-zeroenergy” was possible for the presented case study area. The originality of this work lies in developingand applying an informed retrofitting (nearly-zero energy) guide to be used as a benchmark energymodel for buildings that belong to an important historical era. The findings contribute to fill a gap inexisting studies of integrating renewable energy sources to achieve “nearly-zero energy” in heritagebuildings in hot climates.