Trihybrid Method for Energy Efficiency Retrofitting of Public Housing in a Hot Arid Climate: A Case Study in the UAE

A huge stock of existing public housing schemes in the United Arab Emirates (UAE), which were developed before devising and applying energy efficiency and sustainability codes and regulations, fall short of meeting the local energy use intensity (EUI) benchmarks and achieving the local agenda for sustainable development goals (SDGs), especially Goal 11: Sustainable Cities and Communities. While energy efficiency retrofitting systems have been chiefly used by adding a thermal insulation layer over the external envelope of houses, in this research, a new trihybrid energy efficiency retrofitting method containing external thermal insulation cladding integrated with both green infrastructure (GI) and building integrated photovoltaics (BIPVs) is suggested as a more sustainable retrofitting system that could meet the local EUI benchmarks and significantly contribute to achieving SDGs in the public housing sector in the UAE. Accordingly, a case study house model that was widely developed in the UAE was selected and digitally modeled as a building information modeling (BIM) base model. Then, four alternative scenarios for the proposed trihybrid retrofitting method were suggested, with each consisting of different combinations of carefully selected efficient conventional retrofitting cladding materials, a GI living wall, and BIPV systems. These scenarios were digitally modeled as BIM Digital Twins and were then simulated for their anticipated thermal and energy performance by employing intentionally simple but reliable simulation tools. The scenario for the trihybrid cladding method, which consisted of added thermal insulation cladding of more than 50% of the external wall area, a green wall over the remaining 50% of the external wall area, added window films, and an extended BIPV system, managed to fully meet the optimal local EUI benchmark with a reasonable capital cost and payback period.