What is a Display Energy Certificate (DEC)

A Display Energy Certificate (DEC), is a legally required document for all public buildings with a floor area greater than 250m2, covering the operational rating and energy performance of the buildings.

A ‘Public Building‘ is defined as a building occupied by a public authority, which also includes Central or Local Government, and some non-departmental public bodies which are visited frequently by the public.

The Display Energy Certificate (DEC) shows the CO2 emissions of a building within a graphical scale from A to G, where A has the best or lowest CO2 emissions and G has worst or highest CO2 emissions, and it is calculated on the actual amount of metered energy used by the building over the last 12 months. The DEC is very useful as a visual benchmarking tool as you can compare the last 3 years energy consumption figures at a glance.

It consists of a certificate and an advisory report. Both give information to the general public about the energy consumption and energy efficiency of that building. This assessment must be performed by certified display energy certificate assessors.

Public Display Energy Certificates can only be produced by an accredited Energy Assessor and should be displayed no smaller than A3 in a prominent place clearly visible to members of the public. Fines can be issued for failing to display a DEC and failing to have a valid advisory report.

The DEC states the energy rating of the building from A-G and is based on the potential performance of building fabric (construction), and its services (heating/lighting/ventilation).

The Advisory Report which comes with the DEC shows how the energy performance of the building can be improved.

DECs and Advisory Reports Validity Periods:

The validity of the Display Energy Certificate and The Advisory Report depends on the floor area of the building.

England, Wales & Northern Ireland

For buildings in the above regions, with a floor area greater than 1000m2, the DEC is currently valid for one year and the Advisory report for up to seven years.

For buildings with a floor area greater than 250m2 but less than 1000m2, both the DEC and AR are currently valid for up to ten years.

Should the overall floor area change, or the occupation of the building alter, then a new DEC should be provided. There is currently a large requirement for display energy certificates in London, we can help.



In Scotland, all DEC’s are valid for 12 months, and there is no requirement for an Advisory Report.

DEC Assessment Process;

  • An accredited Energy Assessor must perform a Site Visit, gathering measurements of building, and photographs of services and fabric to confirm inputs into Government approved OrCalc software.
  • Validate and process 12 months utility invoices which have been supplies by the client

Commercial property owners may also commission a ‘voluntary’ Display Energy Certificate (DEC) and Advisory Report and this is a route to ESOS compliance as an alternative to energy audits.

LJ Energy Surveys are certified display energy certificate assessors and can provide Display Energy Certificates in London and throughout the UK.

For your information we have supplied the Governments published document the use of a DECs;

LJ Energy Surveys are qualified and expert energy assessors helping building owners satisfy the requirements of the EPC regulations. Although based in South Shields, Tyne & Wear, cover the whole of the North East on a daily basis, we can however offer site visits and quotations on Commercial EPC’s throughout the UK.

For more information on our Commercial EPC certificate services please contact us or click here to request an inspection.

Commercial EPCs. SBEMs. Display Energy Certificates.

LJ Energy Surveys provide a fast, professional and competitive service and with the added guarantee of regular audits by the accreditation schemes, you can instruct LJ Energy Surveys with total confidence.

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