An Original Contribution to the Measurement and Reduction of Carbon Embodied in Nigerian Building Construction: Life Cycle Assessment Methodology and Emission Benchmarks

Embodied carbon in building construction is the largest contributor to the life cycle greenhouse gas emissions of short-lived buildings in tropical climates, yet no validated life cycle assessment methodology or empirical emission benchmarks have been developed for Nigerian building construction conditions. This study makes an original contribution to embodied carbon measurement and reduction in Nigerian building construction through three interconnected research contributions. Contribution One establishes original embodied carbon emission factors for the 20 most-used building materials in Nigeria through a process life cycle assessment study that accounts for Nigerian manufacturing conditions, energy mix, and logistics, producing a Nigerian Building Materials Embodied Carbon Database covering primary, secondary, and end-of-life emission stages. Contribution Two develops and validates an original Nigerian Building Embodied Carbon Assessment Protocol, adapting the RICS Professional Statement on Whole Life Carbon Assessment to Nigerian data availability and professional practice constraints. The protocol is validated through blind application by 15 practitioner assessors to 5 reference buildings, achieving inter-rater variability below 12%. Contribution Three applies the protocol to calculate embodied carbon benchmarks for seven Nigerian residential and commercial building typologies, using data from detailed material quantity surveys of 70 recently completed projects across all six geopolitical zones. Results show mean embodied carbon intensities ranging from 285 kgCO2e/m2 (simple single-storey residential) to 618 kgCO2e/m2 (multi-storey reinforced concrete commercial), with significant reduction potential (mean: 31%) achievable through locally available low-carbon material substitutions. The study provides the first empirically grounded embodied carbon framework for Nigerian building construction, constituting an original contribution to climate-responsible building technology in West Africa.

Keywords: embodied carbon, life cycle assessment, building materials, Nigerian construction, carbon benchmarks