Impact of BIPV window on building energy consumption and urban microclimate: Model development and sensitivity analysis

Building-integrated photovoltaic technology (BIPV) has been proven as an effective way to increase renewable energy and achieve low-carbon in the urban environment. Due to the lack of modelling tools, the impact of BIPV window in the street canyon has not yet been well understood. To fill the gap, we developed a new parameterization scheme for BIPV window, and incorporated it into building energy simulations coupled with a single-layer urban canyon model. Model evaluation suggests that the coupled model is able to reasonably capture the diurnal profiles of BIPV window temperature and power generation, building cooling load, and outdoor microclimate. Results of summer simulations in different street canyons show that BIPV windows can reduce canyon air temperature and building cooling load compared to clear glass windows. The benefits become more obvious in canyons with more solar exposure and larger window coverage. Considering the large variability of urban settings in affecting BIPV window performance, we applied the Markov chain Monte Carlo algorithm to conduct extensive simulations to quantify the influence of various uncertain input parameters. Canyon aspect ratio, window coverage, and power generation efficiency are the most critical factors in maximizing the power generation of BIPV windows. Canyon air temperature and building cooling load are highly sensitive to momentum roughness length above canyon, thickness of building envelope, air conditioning setpoint, and canyon aspect ratio. This indicates a strong dynamic interaction between the building indoors and the surrounding canyon environment. In contrast, the thermal and optical properties of BIPV windows have a negligible impact on the urban thermal environment. Findings in this study reveal the key mechanisms that regulate the urban microclimate and building energy consumption, provide guidance for BIPV application in the built environment, and cast light on the construction of sustainable and low-carbon neighborhoods.