Developing a Life Cycle Assessment Methodology for Structural Material Selection in Nigerian Building Construction Incorporating Local Carbon Emission Factors

Life cycle assessment of structural materials provides a rigorous basis for quantifying and comparing the environmental impact of structural design choices, yet existing life cycle assessment databases and carbon emission factors are dominated by European and North American supply chain data that misrepresent the carbon intensities of material production, transportation, and construction processes in Nigeria. This study develops a life cycle assessment methodology for structural material selection in Nigerian building construction that incorporates locally derived carbon emission factors for the principal structural materials and construction processes in use across the South West, South South, and North Central geopolitical zones. Primary data on energy consumption, fuel use, and process outputs were collected from cement production facilities, steel reinforcement mills, timber treatment plants, and concrete batching operations in Lagos, Port Harcourt, and Abuja through structured industry surveys and facility audits. Inventory analysis was conducted using SimaPro lifecycle assessment software with locally derived background datasets, and environmental impact profiles were computed for reinforced concrete, structural steel, and composite structural systems across a standard six-storey office building reference case. Results indicate that the carbon emission factor for Nigerian-produced cement is 0.92 kg CO2e per kg, 12 percent higher than the European reference value due to greater clinker-to-cement ratio and lower thermal efficiency in Nigerian kilns. Reinforced concrete using Nigerian-produced cement generates 33 percent higher embodied carbon per kilogram than European benchmarks, significantly altering the comparative environmental impact of reinforced concrete versus imported structural steel. The original methodological contribution is the derivation of a Nigerian structural materials life cycle inventory database and a decision-support tool for structural material comparison under multiple environmental impact categories. Keywords: life cycle assessment, structural materials, embodied carbon, Nigerian construction, sustainability.