Boiler Efficiency

Gas boiler efficiency levels

Boiler Efficiency EPC

Boiler Efficiency EPC

The current boiler grant scheme which is seeing thousands of homes across the UK have free replacement boilers installed is in place to raise the levels of boiler efficiency throughout the country. By fitting free condensing boilers the Government hope to lower Carbon emissions nationally through less energy consumption.

The organisation which determines a boiler’s grading is SEDBUK (Season Efficiency of Domestic Boilers in the UK). SEDBUK 

Boiler ratings are determined are determined when the boiler and hot water / heating system is installed, although it is possible to have it assessed at any time by a Domestic Energy Assessor.

Boiler performance contributes to the overall energy performance of your property and is included in any Energy Performance Certificate or Report

Boiler performance is measured as a percentage although the European Grading method (A-G according to energy usage performance) is also often included for consistency.

The energy efficiency of gas boilers (the free boilers available in the UK are gas boilers) is assessed on a variety of factors including 

  • Seasonal conditions
  • Boiler / heating usage patterns
  • Housing occupancy at the time of boiler installation
  • Boiler storage conditions
  • Boiler Location
  • Boiler insulation

Other factors deemed to affect the energy efficiency of boilers such as climate and the age of a boiler are also taken into account when assessing a boiler’s performance. 

The boiler rating system is designed to be a fair and accurate method of determining boiler efficiency, regardless of manufacturer.

The table below reflects the energy rating and performance rating system used by SEDBUK to measure boiler efficiency.

 SEDBUK Band Boiler Rating
Boiler energy
performance data

Band A
 Above 90%
 Boilers in this band function at over 90% efficiency
Band B
 86%-90%  Boilers in this band function at 86%-90%  efficiency
Band C
 82%-86%  Boilers in this band function at 82%-86% efficiency
Band D
78%-82%  Boilers in this band function at 78%-82% efficiency
Band E
 74%-78%  Boilers in this band function at 74%-78% efficiency
Band F
 Boilers in this band function at 70%-74% efficiency
Band G
 Below 70%
 Boilers in this band function at below 70% efficiency

Boiler Grants Home | Boiler Grant Criteria