A systematic review of consequential LCA on buildings: the perspectives and challenges of applications and inventory modelling

Purpose: The built environment has demonstrated the limited nature of applications of consequential LCA (LCA), whereas attributional LCA (ALCA) is applied in most situations. Therefore, this study aims to clarify the contexts in which CLCA might be applied and the state of CLCA on buildings by examining the following research questions: (i) How are the goal, scope and methodological aspects and associated gaps of CLCA of buildings addressed in the literature? (ii) How can these insights guide the applications of CLCA on buildings?

Methods: The study employed the Systematic Literature Review methodology, which yielded 37 relevant studies. The study examined the sample regarding intended applications, the contexts of micro or meso/macro decision-making support, and the consequential life-cycle inventory modelling (CLCI) of time horizons, market delimitations, market volume trends, affected suppliers, constrained supplies and substitution. Furthermore, the basis for choosing either an ALCA or a CLCA approach was evaluated based on the ILCD Handbook.

Results and discussion: Many studies include an empirical assessment, yet with half of those combining it with an evaluation of selected methodological aspects, thus CLCA on buildings seems to still be in the earlier exploration phase. In general, the empirical CLCAs emphasize the decision-making aspect in the stated application of the study. Furthermore, CLCA studies show an almost equal distribution of focus between the micro and meso/macro levels of decision support. This entails that CLCA on buildings currently applies to both material- and building-level assessments and policy situations. The inclusion of CLCI modelling elements varies: e.g., nine studies only include substitution as the single CLCI element. Additionally, modelling methods are described at various levels of detail, and with critical differences in the transparency of documentation. This, therefore, suggests that the consistency of included CLCI elements is inadequate, as is how they should be modelled.

Conclusions and recommendations: Building on the ILCD Handbook, this study presents a proposal for deciding when to select CLCA on buildings. This is a proposal for a simple and clear distinction threshold between the micro and meso/macro levels. Additionally, CLCA on buildings need a more harmonized approach to CLCI modelling to increase and improve, which the built environment community could achieve by settling on a standard for the inclusion of CLCI elements and associated modelling methods.