PUBLIC BUILDING / ACTUAL ENERGY USE
Display Energy Certificate
A Display Energy Certificate (DEC) makes the measured energy use of a qualifying public building visible. Understand the threshold, organise your consumption data and request the assessment with a clear next step.
01 / The perspective
Actual energy use.
Visible evidence.
A public building can look efficient on paper while using more energy than expected in operation. A Display Energy Certificate addresses that gap. Its rating is based on recorded energy consumption, rather than a model of how the building might perform. The certificate is accompanied by an advisory report with recommendations for improving energy performance.
A DEC is generally required where a building has more than 250 m² of useful floor area, is occupied in whole or part by a public authority, and is frequently visited by the public. Private organisations can choose to obtain one voluntarily. The distinction matters: a DEC is not simply a commercial EPC with a different name.
Start with the building, its occupier, the space open to the public and its recent energy records. We will use those details to discuss whether a DEC is the right route and what evidence an accredited assessor will need. A sensible assessment begins with the data, not with an assumed rating.
Who needs a DEC?
The test is about the building and its use. The requirement generally applies to buildings with more than 250 m² of useful floor area that are occupied in whole or part by a public authority and frequently visited by the public. A school, library or public office may be in scope; a private office is not automatically in scope simply because visitors enter it. An accredited energy assessor should confirm the position for the individual building.
Once issued, the DEC must be displayed where it is clearly visible to the public. The advisory report should be available for inspection. If you manage several buildings, assess each qualifying building rather than treating the estate as a single certificate.
What the assessment uses
A DEC reflects operational energy use. Assemble twelve months of electricity, gas and other relevant fuel records, the useful floor area, occupancy details and information about how the building is used. Data quality affects the quality of the assessment: changes in tenancy, missing bills or shared meters should be raised early. The assessor will explain how the prescribed methodology handles the building's circumstances.
The output is an operational rating and an advisory report, not a promise that every recommendation must be carried out. The report helps decision makers identify practical opportunities and investigate why a building uses the energy it does.
Validity depends on floor area
For a building above 1,000 m², the DEC is valid for one year and the advisory report for seven years. For a building above 250 m² and up to 1,000 m², both are valid for ten years. Put the expiry dates in your property compliance calendar, especially where a larger public building needs a fresh DEC every year.
A DEC measures actual use; an EPC models a building's potential energy performance under standardised assumptions. The documents answer different questions, and one should not be substituted for the other without checking the requirement.
The useful details
DEC questions, answered.
Is a DEC required for every commercial building?
No. The mandatory DEC test is tied to public-authority occupancy, public visits and a useful floor area over 250 m². Other non-domestic properties may need a commercial EPC for a different transaction or purpose.
How is a DEC different from an EPC?
A DEC uses recorded energy consumption to describe operational performance. An EPC assesses a building's expected energy efficiency using standardised modelling. They are distinct certificates with different uses.
What should I send with a DEC enquiry?
The address, approximate useful floor area, type of public service, occupier, date the current DEC expires if one exists, and twelve months of energy records if available. We can identify gaps in the initial conversation.
Your next step
Make the building's
energy use visible.
Tell us about the public building, its floor area and your available energy data. We will contact you to agree the right next step.