Paper Conference

Proceedings of uSim Conference 2022: 3rd uSim Conference of IBPSA-Scotland



Simon Lannon, Ed Green

Abstract: Welsh Government has set the ambitious target of a 95% reduction in carbon emissions from the Welsh housing stock. To achieve this goal, a target Energy Performance Certificate rating of 'A' has been established for all dwellings. The literature suggests this is technically possible, but widespread rollout of retrofit that meets this target poses different challenges to the deep retrofit of a single dwelling. Retrofitting the social housing landlords' stock is seen by Welsh Government as an appropriate first step to meet the 2050 target, as landlords have already improved their stock nationally as part of the Welsh Housing Quality Standard programme (2005-2020). This paper presents research that developed a process to enable landlords to understand key actions and challenges related to stock-wide retrofit that meets this target, by moving from top-down typology stock modelling to a case-study-led approach that landlords can apply to their own stock. Case studies ('typical' homes owned by Welsh social housing landlords) were identified through the Welsh House Condition survey and a survey of all social rented dwellings. Retrofit of each case study was modelled thorough to 2030, with an emphasis on the component-led approach adopted by landlords (windows, walls, loft, heating systems, renewables, etc.). The business-as-usual approach of each social housing landlord was compared to a best practice approach to retrofit, and the differences are presented in terms of impact on emissions, fuel bills and cost. The work is based on the UK Standard Assessment Procedure (SAP) steady state monthly model outputs and Energy Performance Certificate rating, which are used as the common language for retrofit proposals. SAP is not an appropriate measure of decarbonisation itself, but is an appropriate tool to measure the improvement in energy efficiency neededto develop a retrofit approach which achieves decarbonisation without negatively impacting on fuel poverty). The modelling compares expected repair, maintenance and improvement with deep retrofit for decarbonisation through installation of heat pumps and renewables, to understand the conflict between fuel cost and carbon reductions. The paper also highlights how overall stock targets of EPC A were created and case studies used to communicate the outcomes of the modelling to a broad audience that included policy makers, housing management teams and project managers.