Interpreting Life Cycle Assessment Across Architectural Decision Orders: Environmental Conflict, Circularity and Temporal Responsibility

Life Cycle Assessment (LCA) is widely applied in building research and practice to quantify environmental impacts, yet its contribution to architectural decision-making remains limited. This paper argues that this limitation is not primarily methodological, but interpretative. LCA results are often presented independently of the hierarchy, timing, and reversibility of architectural decisions, obscuring where environmental responsibility can meaningfully be exercised. This study reframes LCA as an interpretative tool for understanding environmental responsibility across successive orders of architectural decision-making. A conceptual framework linking decision hierarchy, reversibility, and the temporal distribution of impacts is developed and examined through six deliberately selected case studies drawn from the peer-reviewed literature. The cases span early geometric and structural decisions, retrofit strategies, operational constraints, regulatory lock-in, and methodological assumptions. The analysis shows that the effectiveness of LCA varies systematically with decision order. At early design stages, LCA can inform highly irreversible choices and shape long-term environmental trajectories. At later stages, its role shifts toward exposing constrained trade-offs, residual conflicts, and limited remaining agency rather than enabling optimisation. By explicitly linking life-cycle impacts to decision hierarchy and time, this paper addresses a conceptual gap in current LCA research and supports more reflective architectural decision-making under uncertainty.