A multi-stage multi-objective optimization method for balancing the impacts of energy efficiency strategies on buildings

The building sector significantly contributes to global energy consumption and carbon emissions, making retrofitting a crucial strategy to reduce these impacts. Despite the availability of various retrofit technologies, identifying the most suitable ones for specific projects poses a major technical challenge. To address this, the current study has introduced a multi-stage, multi-objective optimization approach, integrating R, Energyplus and Excel for energy/thermal simulations, sensitivity analysis, optimization iterations and financial decision-making. Objective functions include thermal comfort, thermal energy demand, global cost, primary energy consumption and carbon emission equivalent. The functionality of the proposed framework was tested using the energy model of a residential reference building in Northern Cyprus. Cost-optimal recommendations included applying external wall thermal insulation, independently or with photovoltaics and energy-efficient air-conditioners, necessitating an initial investment of up to 46.40 €/m 2 . This yields potential benefits with up to 56.10% primary energy savings and a 35.17% reduction in global cost. Another option, replacing windows independently or with external shutters, applying thermal insulation and installing photovoltaics and energy-efficient air-conditioners, requires an initial investment of up to 536.70 €/m 2 , offering potential benefits with up to 58.52% primary energy savings. However, a substantial 89.49% increase in global costs is noted due to high initial investment costs.