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Letter: Reform of domestic EPC rating metrics to Patrick Harvie MSP

1. Outline

This is a letter from Lord Deben, Chair of the Climate Change Committee, to Patrick Harvie MSP, Minister for Zero Carbon Buildings, Active Travel and Tenants’ Rights. It explains the need for modifying the rating metrics used on domestic Energy Performance Certificates. It outlines our recommendations for improvements to the metrics to make them better for informing consumers and supporting policies to reduce emissions from homes.  

2. Key messages

  • The ratings on EPCs are an important policy tool – used to define standards and targets for reducing emissions from homes – but are poorly suited to this role. 
  • The current EPC rating metrics do not accurately incentivise the energy efficiency and heating solutions required to deliver Net Zero homes. 
  • EPC rating metrics should be improved, so they are easier to understand, can be compared with actual performance, and enable policies to be better targeted. 
  • Domestic EPCs should include four primary metrics, using real-world units, and clear simple names: 
    • ‘Energy’: Total energy use intensity (kWh/m2/yr) 
    • ‘Fabric’: Space heating demand intensity (kWh/m2/yr) 
    • ‘Heating’: Heating system type (categories of heating system, ranked from 1 to 6). 
    • ‘Cost’: Energy cost intensity (£/m2/yr).  
  • Reforms to EPC rating metrics should be applied alongside wider improvements to the EPC system to improve the quality of assessments and use of data. EPCs could also be expanded to provide information on risks posed by climate change and ways to reduce these.