BIM-based techno-economic assessment of energy retrofitting residential buildings in hot humid climate

Buildings in hot humid climates are energy intensive to operate. Energy consumption in Saudi Arabia is almost three times higher than the global average, and one of the major contributors to that is the residential sector. Increasing environmental and economic concerns, in the form of Saudi Vision 2030, mean that the existing unsustainable residential building stock has to be energy retrofitted. This study examines the techno-economic feasibility of retrofitting existing homes in Eastern Province, Saudi Arabia. A Building Information Modelling (BIM)-based retrofit framework has been adopted and investigated on two case studies. Eight Energy Efficiency Measures (EEMs) have been implemented including increasing cooling set point temperature, using energy efficient appliances, replacing conventional lights with more efficient lights, applying window shading, improving glazing type, improving air tightness, using more efficient air conditioning system, and adding envelope insulation. A three-level energy retrofit plan is proposed. Results indicate that annual energy consumption in a villa is reduced by 13.79%, 19.27% and 56.9%, and in the apartment building by 22.84%, 28.85% and 58.5% through a level 1, 2 and 3 retrofit respectively. Compound Payback Period (CPP) was computed to assess the economic viability. For the villa, investing in a level 1, 2 and 3 retrofit will pay back in 0.92, 8.37 and 25.15 years respectively, while for the apartment building, the payback period is 0.60, 11.28 and 24.60 years respectively. Thus, energy retrofitting of existing homes has the potential to significantly reduce energy consumption, however, it is economically not viable in the existing scenario. Electricity tariffs need to be further increased and coupled with incentive programs to render deep energy retrofits feasible. Furthermore, the investigated BIM-based approach can be adopted to investigate energy retrofitting in other climate zones of Saudi Arabia and other countries in the region, and eventually be adopted to efficiently effectuate the colossal task of retrofitting the whole existing residential building stocks of these countries.