Mitigating urban climate-energy feedback with citywide building-integrated photovoltaics implementation

Urban heat islands (UHIs) intensify cooling demands, whose waste heat further exacerbates UHI, creating a self-reinforcing feedback loop. Building-integrated photovoltaics (BIPV) can break this cycle by generating electricity and altering urban climate-energy interactions, yet its net impact remains unresolved. Using a cross-scale modeling framework for 118,521 buildings in Hong Kong, we demonstrate that BIPV glazing reduces cooling demand through improved insulation and lower solar heat gain, while inducing diurnal thermal asymmetry of daytime warming (up to +1.9°C) and nighttime cooling (up to −2.5°C). This microclimate regulation indirectly contributes to a 0.6% reduction in citywide building energy use. Cumulative savings from electricity generation and reduced energy use reach 4.7% (2,060.2 GWh) and 10.1% (4,401.3 GWh) under low- and high-coverage deployment, respectively, with building-level savings of −20.1% ± 11.7% (mean ± SD) at high coverage. We establish BIPV as a configurable climate-energy regulator that enables net-zero, heat-resilient planning and quantifies deployment trade-offs in cooling-dominated cities worldwide. • Cross-scale modeling reveals BIPV’s dual role in urban climate-energy feedback • BIPV creates diurnal thermal asymmetry: daytime warming versus nighttime cooling • Daytime warming is localized to canyons, with façades receiving maximum solar absorption • Citywide net energy use reduces by 10.1% via generation and feedback modulation • Optimal BIPV strategy requires balancing energy yield with urban thermal impact Conventional urban planning often treats renewable energy generation, building efficiency, and heat mitigation as isolated challenges, fundamentally overlooking their critical and synergistic interactions. Our research proposes a paradigm shift by leveraging building-integrated photovoltaics (BIPV) as a synergistic solution. We demonstrate that solar façades can be strategically designed to simultaneously generate power, reduce net energy demand, and cool urban environments. We provide the critical cross-scale modeling framework necessary to guide this transition. Our long-term ambition is to empower planners with digital tools for designing “climate-positive” cities, driving the interdisciplinary collaboration needed to enhance urban livability and resilience. Citywide building-integrated solar façades do more than generate power; they induce localized daytime warming but widespread nighttime cooling. This combined effect breaks the vicious cycle of urban warming and rising energy demand, achieving 10.1% net energy savings and redefining solar façades as dynamic climate regulators.