Energy performance certificates (EPCs) are a rating scheme to summarise the energy efficiency of buildings.^[1][2] The building is given a rating between A (Very efficient) - G (Inefficient). The EPC will also include tips about the most cost-effective ways to improve the home energy rating. Energy performance certificates are used in many countries.

EPCs are administered and regulated for separately in (a) England and Wales, (b) Scotland and (c) Northern Ireland.

EPCs were introduced in England and Wales on 1 August 2007 as part of Home Information Packs (HIPs) for domestic properties with four or more bedrooms. Over time this requirement was extended to smaller properties.^[3] When the requirement for HIPs was removed in May 2010, the requirement for EPCs continued. Rental properties, which have a certificate valid for 10 years, became required on a new tenancy commencing on or after 1 October 2008.^[4]

The legislative basis for EPCs in the UK is European Union Directive 2010/31/EU^[5] as transposed into UK law by:

• The Energy Performance of Buildings (England and Wales) Regulations 2012 (S.I. 2012/3318) (as amended), in relation to England and Wales,
• The Energy Performance of Buildings (Scotland) Regulations 2008 (S.S.I 2008/309) (as amended), in relation to Scotland,
• The Energy Performance of Buildings (Certificates and Inspections) Regulations (Northern Ireland) 2008 (S.I. 2008/170) (as amended), in relation to Northern Ireland.

The energy assessment needed to produce an EPC is performed by a qualified and accredited energy assessor who visits the property, examines key items such as cavity wall, floor and loft insulation, domestic boiler, hot water tank, radiators, heating controls windows for double glazing, and so on. They then input the observations into a software program which performs the calculation of energy efficiency. The program gives a single number for the rating of energy efficiency, and a recommended value of the potential for improvement. There are similar figures for environmental impact. A table of estimated annual energy bills (and the potential for improvement) is also presented, but without any reference to householder bills. The householder will have to pay for the survey, which costs around £75 - £100 for a four bedroom house. The exercise is entirely non-invasive, so the software will make assumptions on the insulation properties of various elements of the property based on age and construction type. The assessor has the ability to over-ride these assumptions if visual or written evidence is provided to support the presence of insulation which may have been subsequently installed.

The calculation of the energy rating on the EPC is based on the Standard Assessment Procedure (SAP). Existing dwellings are assessed using Reduced Data SAP (RdSAP), a simplified version of the SAP methodology that requires fewer data inputs. SAP and RdSAP are derived from the UK Building Research Establishment's Domestic Energy Model (BREDEM), which was originally developed in the 1980s and also underlies the NHER Rating. EPCs are produced by domestic energy assessors who are registered under an approved certification scheme.

In addition to the requirements in relation to dwellings there is also a requirement for EPCs on the sale, rent or construction of buildings other than dwellings with a floor area greater than 50m² from 6 April 2008, that contain fixed services that condition the interior environment.^[11]

Properties that are exempt from requiring a domestic EPC will generally require a non-domestic energy performance certificate, which was also required by the Energy Performance of Buildings Directive. Non-dwellings are "responsible for almost 20 per cent of the UK’s energy consumption and carbon emissions."^[12]

All non-domestic EPCs must be carried out by, or under the direct supervision of, a trained non-domestic energy assessor, registered with an approved accreditation body. The Department for Levelling Up, Housing and Communities (DLUHC), formerly the Ministry for Housing, Communities and Local Government (MHCLG), has arranged for a publicly accessible central register

There are three levels of building, Level 3, Level 4 and Level 5. The complexity and the services used by that building will determine which level it falls under. The Commercial Energy Assessor must be qualified to the level of the building to carry out the inspection.

From October 2008 all buildings including factories, offices, retail premises and public sector buildings - must have an EPC whenever the building is sold, built or rented. Public buildings in England and Wales (but not Scotland) also require a display energy certificate showing actual energy use, and not just the theoretical energy rating. From January 2009 inspections for air conditioning systems will be introduced.

Display energy certificates (DECs) show the actual energy usage of a building, the Operational Rating, and help the public see the energy efficiency of a building. This is based on the energy consumption of the building as recorded by gas, electricity and other meters. The DEC should be clearly displayed at all times and clearly visible to the public. A DEC is always accompanied by an Advisory Report that lists cost effective measures to improve the energy rating of the building.

Display energy certificates are only required for buildings with a total useful floor area over 500m² that are occupied by a public authority and institution providing a public service to a large number of persons and therefore visited by those persons. The useful floor area limit will be reduced to 250m² in July 2015.

Where the building has a total useful floor area of more than 1,000m², the DEC is valid for 12 months. The accompanying advisory report is valid for seven years. Where the building has a total useful floor area of between 500m² and 1,000m², the DEC and advisory report are valid for 10 years.

However, to make it easier for public authorities with multiple buildings on one site to comply with the legislation, a site-based approach for the first year (to October 2009) is allowed where it is not possible to produce individual DECs. This means that only one DEC will need to be produced based on the total energy consumption of the buildings on the site. Public bodies most affected by this relaxation are NHS Trusts, universities and schools.

The requirement for display energy certificates came into effect from 1 October 2008. They were trialled in the UK under an EU-funded project also called "Display" and co-ordinated by Energie-Cités; participants included Durham County Council and the Borough of Milton Keynes.

As a rating system, EPCs are known to have reliability issues. Non-domestic EPCs are found to have a regression effect where low-rated properties are more likely to obtain higher ratings in the renewal, while high-rated ones tend to get lower ratings. This directly casts doubts on EPC-based policies like Minimum Energy Efficiency Standards. ^[14]

EPCs have gained some political controversy, partly reflecting the housing market crisis in the United Kingdom (2008).

Many in the housing industry, such as the Royal Institution of Chartered Surveyors, have criticised the introduction of EPCs, on the grounds of poor quality.^[15][16] Whilst critical, RICS still provided courses on domestic energy assessment, as well as courseware manuals for the professions of domestic energy assessors.

A further objection is often made concerning the quality of inspection made to produce the certificate. It cannot be invasive, so the inspector cannot drill walls or ceilings to determine the state or even existence of any insulation. The energy assessor can either assume the worst ('as built' to Building Regulations for the dwelling's age) or rely on the householder to produce documentary evidence on what may have been installed. This can produce uncertainty about the validity of the output from the assessor's analysis.

Finally, EPCs pose particular problems for the owners of listed buildings, as improvements, such as double glazing, are often barred by the controls on changes to such structures, making it difficult to rectify low ratings.

• Energy efficiency in British housing
• Energy policy of the United Kingdom
• Energy policy of the European Union
• Global warming
• Energy White Paper
• Domestic energy assessor
• House energy rating
• Home energy rating