Integrating life cycle assessment and cost analysis in decision making: Optimising design choices in a public building case study

The building sector is responsible for a significant share of global greenhouse gas emissions and resource con¬sumption, with impacts spanning the entire life cycle of buildings from material production to end-of-life. In recent years, there has been a growing recognition of the need to address these impacts through early design decisions, leveraging integrated environmental and economic assessments to inform material and system choices. However, the complexity and time demands of Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) often limit their use to later design stages, reducing their potential as decision-support tools. This study aims to integrate LCA and LCC with a Building Information Modelling (BIM) environment to support data-driven decision-making from the outset of the design process. A methodology was developed to evaluate and compare alternative construction scenarios using BIM-linked LCA and LCC workflows, following EN 15804 and ISO 15686 standards and supporting transparent, scenario-specific comparisons. The approach was applied to a public museum under design in Caceres, Spain, selected for its relevance as a public building type, assuming the role/responsibility of public administrations in driving the digital and environmental transition. Three alternative load-bearing structures—reinforced concrete, mass timber, and a hybrid concrete-clay block system—were assessed while maintaining consistent architectural design. Material quantities were extracted from a parametric BIM model and analysed using interoperable LCA and LCC tools under cradle-to-grave boundaries across 50- and 100-year service lives. The results reveal significant differences between the environmental and economic performance of the alternatives. The timber structure achieves a 55 % reduction in Global Warming Potential compared to reinforced concrete, demonstrating substantial carbon savings. However, this comes with a 56% higher total life cycle cost, underscoring the trade-off between environmental benefits and economic feasibility. The integrated workflow demonstrated its effectiveness in supporting informed design choices aligned with sustainability and financial objectives. The proposed methodology is easily replicable across building typologies, offering a prac¬tical tool for design teams and public clients to advance low-carbon, resource-efficient construction aligned with European sustainability goals.