Decarbonising the welsh housing stock: From practice to policy

This paper examines whether and how the challenging target of 95% decarbonisation can be achieved for the Welsh building stock. First, a critical review of the literature and relevant case studies are presented to understand the effectiveness of different retrofit approaches in practice, and the degree to which these approaches are evidence based, and applicable to the Welsh context. These findings are synthesised into a collection of 14 recurrent dwelling 'archetypes', with appropriate retrofit strategies developed for each. The impacts of these strategies are modelled in terms of capital cost, primary energy use, fuel bills and carbon emissions. Conclusions provide an evidence base for future policy and a decarbonisation strategy. Retrofit strategies should include fabric first-measures to minimise increases in household fuel bills and a consequent increase in fuel poverty. Retrofit options for a significant percentage of housing are constrained by character, which would limit changes to the external fabric. Given that decarbonisation of the future energy supply is currently uncertain, all other housing should be retrofitted to perform beyond SAP90. A flexible approach that pushes all housing to achieve stringent standards by 2050 is the only way to achieve targeted reductions in carbon emissions under the assumed energy supply scenarios. Policy relevance The Welsh housing stock, among the oldest and least efficient in Europe, is responsible for 21% of Welsh carbon emissions. In 2019, the UK Committee for Climate Change (CCC) determined that Wales should target a 95% reduction in emissions by 2050. This paper assesses whether this challenging target can be achieved, and potential strategies for doing so. Key recommendations are drawn from the research, which encompass technical, social and organisational issues, and the importance of a holistic approach to decarbonisation is identified. These findings informed the Independent Steering Group recent report Better Homes, Better Wales, Better World (2019), and the report’s recommendations were adopted by the Welsh Government on 24 September 2019. This work should continue to provide an evidence base upon which future policy can be developed through the development of retrofit strategies for recurring dwelling archetypes and a decarbonisation strategy for Wales that is likely to include legislation, regulation, incentives and penalties.