Display Energy Certificates (DECs)

If you manage or occupy a public building, a Display Energy Certificate (DEC) may be a legal requirement. We provide accurate, accredited DEC assessments to help you stay compliant, reduce energy use, and demonstrate environmental responsibility.

What you need to know.

1) What Is a Display Energy Certificate?

A Display Energy Certificate (DEC) shows how energy-efficient a public building is based on its actual energy consumption over the past 12 months. Like an appliance rating label, a DEC uses a sliding A–G scale, with:

  • A = most efficient (low carbon emissions)

  • G = least efficient (high carbon emissions)

A DEC must be prominently displayed in the building, and is always accompanied by an Advisory Report, which includes recommendations for improving energy performance.

A valid DEC is a legal requirement for many publicly occupied buildings.

2) Which Buildings Need a DEC?

A DEC is required if the building:

  • Is occupied (partially or fully) by a public authority (e.g. local council, school, NHS trust, college)

  • Has a total floor area over 250m²

  • Is frequently visited by the public

Examples include:

  • Town halls

  • Leisure centres

  • Universities

  • Hospitals

  • Libraries

  • Government offices

Failing to have a valid DEC and advisory report can result in financial penalties.

3) Where Must a DEC Be Displayed?

It must be placed in a prominent, publicly visible location

  • Government guidance requires it to be no smaller than A3 in print

You’ll receive a printable PDF version ready for display.

4) What’s in a DEC?

Each Display Energy Certificate includes:

  • Building address & certificate number

  • Date of assessment & expiry

  • Assessor details & accreditation body

  • Energy performance rating (A–G scale)

  • Numerical operational rating score

    • 100 = typical public building

    • Below 100 = better than typical

    • Above 100 = less efficient

  • Annual energy usage (in kWh/m²)

  • % from renewables

  • Annual CO₂ emissions (tonnes)

  • Comparison to past years’ performance

The lower the score and carbon output, the better the building’s efficiency.

5) What Does the Assessment Involve?

A qualified DEC assessor will visit your site to collect:

✅ Building dimensions

✅ Energy meter readings (electricity, gas, renewables, etc.)

✅ Details of heating, cooling, and lighting systems

Using approved software, we generate both your DEC and your Advisory Report, which are delivered via email and ready for printing or online access.

6) What Is the Advisory Report?

The Advisory Report (or Recommendation Report) is provided with every DEC and outlines practical ways to:

  • Improve building energy performance

  • Reduce carbon emissions

  • Introduce low or zero-carbon technologies

  • Make operational/management improvements

This report is valid for 7 or 10 years, depending on building size.

How long does a DEC last?

Building Size DEC Validity Advisory Report Validity
Over 1000 m² 1 year 7 years
250 m² – 1000 m² 10 years 10 years

📌 Buildings over 1000 m² must renew their DEC every year.