This study aims to evaluate the synergistic co-benefits of pollution reduction, carbon mitigation, and economic performance of various urban roof systems using a comprehensive life cycle assessment model. The analysis covers green roofs, photovoltaic (PV) roofs, agricultural roofs, rainwater harvesting roofs, and their composite systems. The results reveal significant disparities in environmental benefits among the systems. The photovoltaic roof demonstrated superior performance in both carbon and air pollutant reduction, with the standalone PV roof achieving an annual CO₂ reduction of 97.62 kg/m². Composite systems, such as "PV + agriculture", enhance this effect, increasing CO₂ reduction by approximately 13% compared to single-function PV roofs. From an economic perspective, although the "PV + agriculture" system has the highest initial cost (165.72 RMB/m²), it generates the greatest total revenue (226.04 RMB/m²) by combining energy and agricultural outputs. The standalone PV system shows the highest net benefit. In contrast, agricultural, green, and rainwater harvesting roofs yielded negative net benefits, indicating their current economic challenges. The study confirms that PV and composite roof systems offer a dual advantage: significant synergistic benefits in reducing both air pollutants and carbon emissions, and compelling economic viability. These findings provide a critical scientific basis for urban planning, supporting the selection of roof systems that simultaneously address climate change, air quality, and economic sustainability challenges.

Pollution and Carbon Reduction,Roof Systems,Life Cycle Assessment (LCA),Co-benefits