Fabric first: is it still the right approach?

‘Fabric first’ describes an approach to improving the thermal performance of residential buildings by prioritising the improvement of fabric. It has historically been widely advocated. However, the urgency of complete decarbonisation challenges this approach in existing buildings. Heat decarbonisation is necessary to deliver zero-carbon goals. In many cases, no additional fabric improvement is needed to decarbonise heating; a heat pump, or other zero-carbon heat supply, will be enough. Retrofitting fabric first may not be feasible across the whole housing stock on timescales necessary for rapid decarbonisation and could therefore slow housing decarbonisation. However, fabric improvement will continue to have an important role. Energy use in buildings with a ‘heat pump only’ retrofit will be higher than if insulation were also improved. Fabric should continue to be prioritised in new buildings and where low-cost insulation measures are available. Fabric improvement can have other benefits: lower running costs, improved comfort, reduced damp risk, better heat pump performance, reduced overheating risk and lower requirements for electricity capacity increases. The suitability of a heat-pump-only approach to building decarbonisation should therefore be decided building by building. For national building stocks, complete decarbonisation of heating systems is required, but stock average fabric improvement may be 30–50%. Policy relevance Combining rapid decarbonisation with comfortable and healthy homes will require coordinated programmes of heating system change and fabric improvement. To develop supply chain and consumer confidence, minimum energy and carbon standards for existing buildings will be needed. High-efficiency heat pumps will need to be the dominant heating technology. As they currently have higher capital costs than fossil fuel boilers, rapid market deployment will require financial incentives. For equity reasons, in low-income households, public and/or landlord funding will be needed. Innovative finance options and/or supply industry obligations may also be useful. Energy regulation and taxation need to ensure that decarbonised options have lower operating costs. Investments will be needed in workforce education, skills and occupational standards, supported by robust quality assurance programmes. Consistent, good quality advice will be needed from both installers and independent advice services. Deployment programmes should be monitored to ensure existing evidence gaps are addressed.