Energy efficiency relates to the concept of efficient energy use, which means using less energy to provide a given amount of heating or lighting. Using less energy reduces emissions of carbon dioxide.


Energy Performance Certificates (EPC) are a measure of the energy efficiency of individual properties. They use information such as building materials, heating systems and insulation to calculate a score on a scale where 1 is least efficient and 100 means the property has zero energy needs. These scores are used to place a property in one of seven EPC bands from G (least efficient) to A (most efficient).

EPC data is not a complete record of energy efficiency for all properties. EPCs have been in place since 2008 for all properties rented, marketed for sale, newly built or applying for some energy efficiency/renewable energy support. Therefore, many properties have no EPCs and some EPCs will be out of date.

The Government has a target that all fuel-poor homes should be at least band C by 2030 and an aspiration for as many as possible homes across the country to be at least band C by 2035.


The Energy Company Obligation (ECO) places an obligation on medium and large energy suppliers to promote measures that improve the ability of low income/fuel poor households in Great Britain to heat their homes.

The Government sets a target for the overall cut in heating costs that ECO should lead to. Each supplier is set a proportion of the overall target based on their relative share of the domestic gas and electricity market.

ECO measures include various forms of insulation, upgrades to heating systems, new heating controls, microgeneration and so on. Their expenditure on the scheme is funded through a levy on domestic gas and electricity bills.

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EPC data

Some EPC data will be out of date (as EPCs are only valid for 10 years) and some properties will be included more than once (for example if a property is sold twice). The ONS makes several quality checks on the EPC data when using it to analyse energy efficiency and removes records which fail them, as well as duplicate records and EPCs over 10 years old. This process removed just over half the records in the database, with the remaining ones used for the 2023 analysis.

ECO data

ECO started in 2013 and is currently in its fourth iteration. ECO4 started in April 2022 and will run to March 2026. It is expected to cost suppliers £4 billion over its four years and provide energy efficiency measures for 450,000 households on the lowest incomes living in properties in EPC bands D to G (or D to E for social housing and private rented accommodation).


Office for National Statistics (ONS), Efficiency of Housing by Westminster parliamentary constituencies, England and Wales, all records up to financial year ending March 2023, 14 November 2023

Office for National Statistics (ONS), Energy Performance Certificate (EPC) Band C or above, England and Wales, 1 November 2023

Office for National Statistics (ONS), Median energy efficiency score, England and Wales, 1 November 2023 Department for Energy Security and Net Zero (DESNZ), Household Energy Efficiency Statistics, 18 January 2024

Data updates

We aim to update this dashboard in line with the latest data releases from the Office for National Statistics (ONS) and the Department for Energy Security and Net Zero (DESNZ), but the data shown here may not be the latest available. MPs and their staff can contact the Commons Library with queries about updates.

Further resources

House of Commons Library, Energy efficiency of UK homes, 19 January 2024

House of Commons Library, Help with energy efficiency, heating and renewable energy in homes, 10 January 2024

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