Assessing the Impact of Green Roofs on Energy Efficiency in Lagos, Nigeria: A Case Study of Ebute Metta's Urbanization

This study assesses the impact of green roofs on building energy efficiency within the hyper-dense, rapidly urbanizing context of Ebute Metta, Lagos, Nigeria. Employing systematic desk research, it synthesizes global evidence and local data to evaluate thermal performance, retrofit viability, and policy frameworks. Findings indicate green roofs can reduce cooling energy consumption by 15-25% in Lagos's tropical climate through evapotranspiration and thermal buffering, significantly lowering peak electricity demand. Key barriers include structural limitations in existing buildings (72% of stock), high installation costs (₦25,000/m2), and policy gaps in Nigeria's building code. Lightweight extensive systems using optimized local substrates (e.g., laterite-stone blends) and drought-tolerant native vegetation are identified as viable retrofit solutions, with community co-operative models reducing payback periods to 6-9 years through cost-sharing and recycled materials. Beyond energy savings, green roofs deliver critical co-benefits including mitigating urban heat islands (4.2°C surface cooling observed in Lagos pilots), reducing stormwater runoff by 27%, and improving air quality. The study concludes that green roofs offer a multi-functional resilience strategy for Ebute Metta but require integrated policy interventions—including revised building mandates, financial incentives (tax rebates, density bonuses), and local supply chain development—to overcome socioeconomic and regulatory hurdles. Recommendations emphasize phased implementation prioritizing public buildings and community-driven models.