A Complete Guide to Display Energy Certificates (DECs) in 2026
## What is a Display Energy Certificate (DEC)?
A Display Energy Certificate (DEC) shows the actual energy usage of a public building (the Operational Rating) and helps the public see the energy efficiency of a building in a clear, A to G scale. It must be displayed prominently, clearly visible to the public.
### Who Needs a DEC?
You are legally required to have a DEC if your building meets **all** of the following criteria:
1. It is at least partially occupied by a public authority (e.g. council, school, NHS)
2. It has a total useful floor area over 250m²
3. It is frequently visited by the public
### How is a DEC Calculated?
Unlike an EPC which rates the theoretical potential of the building's fabric, a DEC is based on actual energy consumption over the last 12 months. The assessor will need:
- 12 months of utility bills (gas, electricity, oil, district heating)
- Floor plans to calculate the Gross Internal Area (GIA)
- Information about the building's operating hours
### The Advisory Report
A DEC must always be accompanied by a valid Advisory Report (AR). This report contains recommendations for improving the energy performance of the building. While the DEC must be displayed to the public, the Advisory Report does not need to be displayed, but must be available upon request.
### Validity Periods
The required frequency of your DEC renewal depends on the size of your building:
**Over 1,000m²**
- DEC: Renewed every 1 year
- Advisory Report: Renewed every 7 years
**250m² – 1,000m²**
- DEC: Renewed every 10 years
- Advisory Report: Renewed every 10 years
### Fines for Non-Compliance
Failing to display a DEC carries a £500 fine. Failing to have a valid advisory report carries an additional £1,000 fine. These fines can be repeated if compliance is not achieved.
[Request a DEC quote](/services/display-energy-certificate) today to ensure your public buildings remain fully compliant.
A Display Energy Certificate (DEC) shows the actual energy usage of a public building (the Operational Rating) and helps the public see the energy efficiency of a building in a clear, A to G scale. It must be displayed prominently, clearly visible to the public.
### Who Needs a DEC?
You are legally required to have a DEC if your building meets **all** of the following criteria:
1. It is at least partially occupied by a public authority (e.g. council, school, NHS)
2. It has a total useful floor area over 250m²
3. It is frequently visited by the public
### How is a DEC Calculated?
Unlike an EPC which rates the theoretical potential of the building's fabric, a DEC is based on actual energy consumption over the last 12 months. The assessor will need:
- 12 months of utility bills (gas, electricity, oil, district heating)
- Floor plans to calculate the Gross Internal Area (GIA)
- Information about the building's operating hours
### The Advisory Report
A DEC must always be accompanied by a valid Advisory Report (AR). This report contains recommendations for improving the energy performance of the building. While the DEC must be displayed to the public, the Advisory Report does not need to be displayed, but must be available upon request.
### Validity Periods
The required frequency of your DEC renewal depends on the size of your building:
**Over 1,000m²**
- DEC: Renewed every 1 year
- Advisory Report: Renewed every 7 years
**250m² – 1,000m²**
- DEC: Renewed every 10 years
- Advisory Report: Renewed every 10 years
### Fines for Non-Compliance
Failing to display a DEC carries a £500 fine. Failing to have a valid advisory report carries an additional £1,000 fine. These fines can be repeated if compliance is not achieved.
[Request a DEC quote](/services/display-energy-certificate) today to ensure your public buildings remain fully compliant.