Potential application of a novel building-integrated solar facade water heating system in a subtropical climate: A case study for school canteen

The design and potential application analysis of the novel solar-absorbing integrated facade module and its corresponding building-integrated solar facade water heating system are presented in this study. Compared with the conventional building envelope, the main novities of the proposed facade module lie in its contributions towards the supplied water preheating to loads and the internal heat gain reduction. Besides, the proposed building-integrated solar facade water heating system broadens the combination modes of the solar thermal system and the building envelope. A dynamic model is introduced first for system design and performance prediction. To evaluate the energy-saving potential and feasibility of the implementation of the proposed facade module, this paper carried out a suitable case study by replacing the conventional facade module in the ongoing retrofitting project of a kitchen, part of the canteen of a graduate school. The detailed thermal performances of three system design options are compared in the typical winter and summer weeks and throughout the year, and then, with the preferred system design, the economic, energy, and environmental effects of the proposed system are evaluated. It was found that the system with a high flow rate of the circulating water is suggested. The annual electricity saved reaches 4175.3 kWh with yearly average thermal efficiency at 46.9%, and its corresponding cost payback time, energy payback time, and greenhouse gas payback time are 3.8, 1.7, 1.7 years, respectively. This study confirms the feasibility and long-term benefits of the proposed building-integrated solar facade water heating system in buildings. © 2023, Tsinghua University Press.