Ten questions concerning absolute sustainability in the built environment

Concepts for setting carrying capacity -based benchmarking of life -cycle environmental impacts is an ongoing field of research with an emerging industrial uptake in the built environment. This paper is a critical review of this development compiled in the form of 10 questions that discusses issues and challenges related to definitions, methodology, terminology, and uncertainties. The intention is not to discourage the development but to highlight the need for ensuring consensus and alignment on the aforementioned issues both within the research community and when implementing concepts in practice. Concluding that AESA (Absolute Environmental Sustainability Assessment) aims to address the environmental performance of a service, benchmarked against a functional pollution space, using environmental carrying capacities, rather than comparing it to current 'best practice'. It is crucial to recognize that these carrying capacities are limits, not targets, and whilst allocation of the carrying capacity to services depends on subjective and political decision -making, uncertainties, including subjectivity and emerging scientific data, should be included and communicated clearly in credible AESAs. Collaboration between academia and industry is crucial to align definitions and terminology and avoid misalignments. While AESA lacks a scalable approach for systemic assessments, it serves as a valuable steppingstone for transition, highlighting that achieving a built environment within the currently known functional pollution spaces, requires policy changes and a cultural shift.