Enhancing cost-efficiency in achieving near-zero energy performance through integrated photovoltaic retrofit solutions

As building energy consumption and greenhouse gas emissions rise globally, retrofitting existing structures offers a pathway toward more sustainable construction practices. However, balancing improvements to technical performance with financial constraints poses challenges. Specifically, whether coordinated implementation of energy retrofits and on-site photovoltaic generation provides synergistic benefits worthy of initial capital investment remains mostly unclear. To address this, the present study evaluates the economic and energy performance impacts of integrated retrofit and renewable energy integration strategies for a university building in Recife, Brazil. In this study, a calibrated building energy model simulated conservation measures and photovoltaic sizing under varying optimization objectives and sensitivities. The most significant contribution lies in its holistic, location-specific approach to achieving near-zero energy status within the educational facility through optimized retrofit strategies. This includes incorporating real-world metered energy data to calibrate the model and inform cost assessments, enhancing practical relevance. Tabu search optimization identified packages minimizing electricity usage intensity and life cycle costs over 25 years. Results indicate that integrating thermal modeling, economic analysis, and optimization identifies synergistic retrofits and photovoltaic sizing configurations reducing consumption by over 45 MWh/yr while improving net present value by more than $170,000 relative to baseline performance without increased investment. Notably, Case 5 achieved 48.6 kWh/m2.yr intensity and $412,978 net present value, reductions of 11% and a 4% increase, respectively, versus the baseline. Occupancy and HVAC emerged as impactful factors highlighting operational adjustment benefits. Findings support deep retrofits coordinated with on-site renewables as a pathway to cost-effectively decarbonize building stocks.