Research on reverse energy-saving design method of zero energy buildings based on building photovoltaic applications

Building energy-saving is an important part of achieving the goals of carbon peak and carbon neutrality. The zero energy building is a more advanced form of nearly zero energy buildings, and reasonable building energy efficiency improvement and building photovoltaic (PV) application are the key technical measures to achieve the goal of zero energy. With the improvement of building energy efficiency standards, the energy-saving marginal benefit of active and passive technologies is narrowing, and with the recent sharp decline in the cost of building PV applications, the priority application sequence of “passive technology, active technology, PV application technology” to achieve zero energy buildings needs to be re-evaluated. This paper proposes the concept and calculation formula of building PV power generation intensity, analyses the influence of building-related parameters on PV application and power generation, optimizes the energy efficiency improvement potential of active and passive technologies, compares the unit energy-saving incremental cost of building PV application and building energy efficiency improvement, proposes a reverse energy-saving design method for zero energy buildings and illustrates it through cases. The results show that the upper limit of the extreme value of building PV power generation intensity is 83-162 kWh/(m2·a) and the lower limit is 15-30 kWh/(m2·a) under different annual solar radiation levels. The unit energy-saving incremental costs of roof PV, facade wall PV, and glass curtain wall PV are 2.37-2.68, 12.62-14.28, and 31.55-35.71 yuan/kWh, respectively. The building energy-saving incremental cost under different combinations of active and passive technologies is 2.86-31.55 yuan/kWh. In the design of zero energy buildings, the priority should be given to the full-coverage design of roof PV systems. By using the maximum power generation of roof PV systems to infer the technical path for building energy-saving, the cost balance point between the active and passive energy-saving technologies of buildings and the facade wall PV should be sought. Finally, whether to apply glass curtain wall PV systems should be considered.