Abstract

This study brings together Life Cycle Assessment (LCA), social practice theory and graph theory to incorporate consumption into environmental impact quantification and environmental design. Environmental design is bound by the underlying environmental impact quantification method, the most holistic and widely used method is LCA. Thus, any modelling choices within LCA are carried through to the environmental design stages. This thesis provides a framework offering a new perspective by incorporating consumption into LCA and environmental design, using a case study on the face covering use during the COVID-19 pandemic.

LCA is conducted on face coverings utilising the conventional approach and through a social practice theory lens, allowing a comparison between the two. The findings highlight the need for the Functional Unit to focus not solely of the product but the practice as a whole for a fair comparison. This is done by changing the Functional Unit of face coverings from Filtration Efficiency, product centred, to Fitted Filtration Efficiency, practice centred. The fair comparison conventional LCA produces limits the inclusion of user behaviour and consumption practices. This research collects use phase data for face covering and compares these to a conventional LCA perspective. Allowing the exploration into sub-practice between products, represented by a focus of usespan instead of lifespan, different scenarios for each product and wider system boundaries. Thus, highlighting the difference in environmental impacts based of the perspective taken.

Interviews are then conducted to gather components for the practice of using a face covering. Social practice theory and graph theory are then used to diagram out the practices and sub-practices. This allows the components of social practice theory (material, meaning and competencies) to be explored and built into the design phase of the product. This leads to design that is focused on the reason for consumption rather than solely on efficiency finding in the production of products. This empirical evidence is then used to produce a novel framework based on social practice theory, to offer better decision making in eco-design and decisions made based of the LCA.