A Simplified Life Cycle Assessment Framework for Early-Stage Material Selection in Sustainable Construction

The construction sector remains one of the largest contributors to global greenhouse gas emissions, largely due to material extraction, production, and transportation. Life Cycle Assessment (LCA) is widely recognized as an essential tool for evaluating environmental impacts, yet its practical application during early design stages is often limited by data complexity and time constraints. This study proposes a simplified LCA framework to support rapid, informed decision-making for material selection in the early phases of building design.Following the ISO 14040/14044 standards, a cradle-to-gate approach (Modules A1-A3) was adopted to compare two common structural materials, concrete and timber, using published embodied carbon factors from the Inventory of Carbon and Energy (ICE) database. The framework was structured around four simplified stages: goal definition, streamlined inventory analysis, impact estimation, and interpretation, enabling designers to obtain indicative environmental results without requiring detailed site-specific data.Results showed that in situ concrete (C30/37, UK average) presented an embodied carbon factor of approximately 0.103 kg CO2e/kg, while structural timber ranged between 0.3 and 0.5 kg CO2e/kg. Although timber appeared less favorable on a per-kilogram basis, this outcome highlights the critical influence of the functional unit selection in LCA: due to timber's lower density, volumetric or structurally-equivalent comparisons typically favor timber over concrete, underscoring a key methodological consideration for practitioners.The proposed simplified LCA framework offers a practical, accessible tool for architects and engineers to integrate environmental considerations early in the design process, while illustrating how functional unit choice can significantly influence material comparison outcomes.