​The purpose of the DEC is, through a A to G rating system (G being the worst performing) to highlight to members of the public and building users how energy efficiently the building is being operated.​ The exemptions are places of worship, temporary buildings, and buildings scheduled for demolition.

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Voluntary assessments can also be completed for any properties to provide an indication of their relative efficiency.

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Validity of mandatory DEC assessments

Buildings with a total floor area over 1,000 m2

• The DEC is valid for one year

• The Advisory Report is valid for seven years.

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Buildings with a total floor area under 1,000 m2

• The DEC and Advisory Report are both valid for ten years​

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Display Energy Certificate (DEC) calculation

There are three components to a DEC assessment

• Collation of the energy consumption data for a 12 month period.  This will include all energy sources such as grid electricity and gas supplies, district heating and cooling, and on site renewable generation.

• Determination and/or confirmation of the total floor area

• Identify the appropriate benchmark category, i.e. office, museum, school, etc.

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On completion the assessment is lodged on the publicly accessible register enter the property post code to access the records.

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Compliance enforcement and penalties

The compliance of Display Energy Certificates (DECs) is enforced by local authorities. They are responsible for ensuring that public buildings display their energy performance ratings prominently and that the information is up-to-date.  Failure to do so can result in a fine of £1,500.

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