Transparent or hidden choices: Exploring perceptions and practices of LCA in building projects

• Undefined goals and scope create cascading effects, obscuring LCA assumptions. • Practitioners’ understanding of LCA often misaligns with documented case studies due to limited sharing of methodological details. • Key modelling choices remain hidden because practitioners prioritise delivering clear and simplified results. • A lack of methodological transparency and compliance-driven LCA about methodological choices creates a “valley of distrust”. • Choice Awareness Theory, developed within the field of energy planning, exposes hidden constraints in LCA and partial truths in results. This study investigates the alignment between methodological considerations and the perceptions of Life Cycle Assessment (LCA) practitioners, and how these factors shape the role of LCA in driving sustainability in the construction sector. Taking a social constructivist approach, the study employs a mixed-methods design, analysing the communication of methodological choices and results in 16 Danish building LCAs, complemented by eight interviews with LCA practitioners. The findings reveal that practitioners struggle to effectively communicate LCA results, particularly balancing the need for transparency with delivering clear, actionable information. In particular, none of the 16 cases adequately communicated their functional unit, system boundary, or impact assessment method, nor did they report impact categories beyond Global Warming Potential (GWP). Moreover, semi-structured interviews with eight LCA practitioners revealed that current LCA practice is focused on complying with legislation and certifications, rather than environmental performance. These findings show that LCA is often reduced to a compliance tool, with a narrow GWP. This limits LCA’s potential to foster broader sustainability objectives, as its effectiveness depends on the understanding and use of the method by stakeholders. By linking to Choice Awareness Theory, we argue that practitioners experience an “illusion of choice” which may reduce trust in LCA results. Future research could investigate communication strategies suitable for presenting LCA-results and how validation of LCAs could be enhanced, including who should validate them.