Sustainability by design: the impact of product architecture decisions on the sustainability of products – a practitioner qualitative assessment <jats:title>ABSTRACT:</jats:title> <jats:p>Sustainability is a central challenge in engineering. Early architectural design decisions strongly influence a product’s ecological footprint and long-term sustainability potential. Addressing these aspects in the concept phase is therefore essential. This paper analyses how architecture decisions - such as modularity, standardisation, redundancy, and updateability - affect ecological sustainability. The qualitative assessment helps practitioners to anticipate environmental impacts and foster sustainability awareness in product architecture development.</jats:p> 6 1291-1300 1291-1300 Cambridge University Press (CUP)