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Energy Efficiency

Energy Performance Certificates (EPC) and Your Boiler

How does your boiler affect your home's EPC rating — and can a new boiler improve it significantly?

24 December 2025·5 min read·By Corby Boiler Installations

EPC Ratings and Boiler Impact

An Energy Performance Certificate (EPC) rates your home's energy efficiency from A (most efficient) to G (least efficient). The heating system has a major impact on your EPC score.

How Much Does a New Boiler Improve EPC?

Replacing a G-rated old boiler with a modern A-rated condensing boiler can improve an EPC rating by 5–15 SAP points — often moving a property from E to D, or D to C.

Why EPC Matters

  • Rental properties must achieve minimum E rating (legal requirement)
  • Higher EPC = lower energy bills
  • Higher EPC can improve property value
  • Some mortgage products offer better rates for high EPC homes ('green mortgages')

Other Heating Improvements That Boost EPC

  • Adding thermostatic radiator valves
  • Fitting a programmer and room thermostat
  • Installing a smart thermostat with weather compensation
  • Upgrading to a heat pump (major EPC improvement)
#EPC#energy performance#efficiency rating

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