Enhancing Urban Sustainability through Green Roofs: A Comprehensive Review of Carbon Sequestration and Energy Efficiency

Green roofs have gained prominence as sustainable solutions to urban challenges, addressing climate change, urban heat effects, and the need for enhanced energy efficiency. This review evaluates how green roofs contribute to urban sustainability by examining their dual roles in carbon sequestration and energy efficiency. The objectives are to synthesize empirical evidence on vegetation- and substrate-driven carbon dynamics, assess the extent to which green roofs reduce building energy demand, and identify the environmental and policy conditions that shape their performance. A PRISMA-based systematic literature review was used across five major databases to examine green roofs’ carbon sequestration and energy-efficiency benefits. From 3,000 records, 80 peer-reviewed studies met the inclusion criteria. Thematic analysis synthesized evidence on carbon dynamics and thermal performance, though language and database limitations remain. Findings reveal that green roofs deliver measurable environmental benefits. Vegetation species such as Sedum acre and Frankenia thymifolia directly sequester atmospheric carbon, while substrate microbial processes enhance long-term carbon storage. Indirect carbon reductions stemming from lower energy demand often exceed direct sequestration. Green roofs also lower cooling loads by up to 70%, reduce indoor temperatures significantly during peak heat periods, and contribute to urban heat island mitigation. Performance varies according to vegetation type, substrate depth, seasonal conditions, and maintenance practices. The study concludes that green roofs hold substantial potential for climate-responsive urban development. It recommends stronger policy frameworks, targeted financial incentives, standardized performance metrics, and expanded research on substrate science. Integrating green roofs into broader green infrastructure networks and ensuring equitable access, especially for vulnerable communities, will further enhance their sustainability impact.