Evaluation of the energy and environmental performance of a novel BIPV window system for net-zero energy buildings

This study analyzes the indoor environmental performance, energy efficiency, and power generation effects of a horizontal solar strip window (HSSW) employed as a building-integrated photovoltaic system in an elementary school. Using DesignBuilder simulations, the indoor illuminance, indoor temperature, heating and cooling energy demand, lighting energy consumption, power generation capacity, and potential electricity-cost savings are evaluated. The results show that, compared to the reference model employing a low-emissivity window, the HSSW model exhibits a higher annual solar heat gain and indoor temperature, which leads to a lower heating demand and a slight increase in the cooling demand. Due to lower heat loss and higher visible light transmittance, the HSSW model reduces the annual total energy consumption by 1.66%. It also generates 60,575.8 kWh of electricity annually, offsetting the building’s total energy use and producing a surplus of 13,460.99 kWh. Employing a net metering scheme with this surplus leads to an annual electricity cost reduction of approximately 1.44 million KRW, illustrating the feasibility of HSSWs as a cost-saving prosumer energy solution. Collectively, these results highlight the potential of HSSWs to contribute to the establishment of net-zero energy buildings and suggest that combining HSSWs with virtual power plants, peer-to-peer energy trading, and energy storage systems may further enhance their economic and energy efficiency.