DEC Certificates Explained
If you operate a public building, a Display Energy Certificate (DEC) may be a legal requirement. More importantly, it provides valuable insight into how efficiently your building is performing in real-world conditions.
At Douglas Energy Solutions, we help organisations across the UK achieve compliance while identifying practical opportunities to reduce energy consumption, lower operating costs, and improve environmental performance.
What Is a Display Energy Certificate?
A Display Energy Certificate measures the actual energy performance of a building based on its energy consumption over the previous 12 months.
Unlike an Energy Performance Certificate (EPC), which assesses how a building should perform, a DEC reflects how efficiently the building is being operated in practice.
Buildings are awarded a rating from A to G, with A representing excellent energy performance and G indicating poor performance. The certificate must be displayed in a prominent location where it can be seen by members of the public.
Who Needs a DEC?
A Display Energy Certificate is typically required if a building:
Is occupied by a public authority.
Has a total useful floor area greater than 250m².
Is regularly visited by members of the public.
Examples include:
Schools and colleges.
Hospitals and healthcare facilities.
Libraries and museums.
Leisure centres.
Council offices and community buildings.
If you are unsure whether your organisation requires a DEC, seeking professional advice can help ensure compliance with current legislation.
How Long Is a DEC Valid?
The validity period depends on the size of the building.
For buildings larger than 1,000m², a new DEC must be produced every year, with the accompanying Advisory Report remaining valid for seven years.
For buildings between 250m² and 1,000m², both the DEC and Advisory Report remain valid for ten years.
Maintaining an up-to-date certificate is essential to avoid potential enforcement action and demonstrate good energy management practices.
DEC vs EPC: What's the Difference?
A common misconception is that a DEC and an EPC are the same thing.
An EPC assesses the theoretical energy efficiency of a building based on its construction and installed services. It is typically required when a property is sold or leased.
A DEC, however, measures actual energy usage and is primarily intended for public buildings.
This means a building can achieve a strong EPC rating but still perform poorly on its DEC if energy consumption is not being managed effectively.
What Information Is Required?
To complete a Display Energy Certificate assessment, the following information is generally required:
Twelve months of electricity consumption data.
Twelve months of gas consumption data.
Records of alternative fuels such as oil or LPG where applicable.
Confirmation of the building floor area.
Details of any renewable technologies, including solar PV systems.
Information relating to occupancy and operational hours.
Providing accurate information ensures the assessment reflects the true operational performance of the building.
What Is Included in the Advisory Report?
Every DEC includes an Advisory Report that identifies opportunities to improve energy efficiency.
Recommendations may include:
LED lighting upgrades.
Heating control improvements.
Building Management System optimisation.
Enhanced energy monitoring and targeting.
Renewable energy opportunities.
Staff engagement and behavioural initiatives.
These recommendations can help organisations reduce operating costs while improving future DEC ratings.
Why Are Display Energy Certificates Important?
Although DECs are a legal requirement for many public buildings, they also provide a valuable framework for understanding energy performance.
The benefits include:
Lower energy costs.
Reduced carbon emissions.
Improved public accountability.
Greater visibility of operational inefficiencies.
Support for wider sustainability and Net Zero objectives.
By understanding how a building performs in reality, organisations can make informed decisions about future investments and energy-saving initiatives.
Need Support With Your Display Energy Certificate?
At Douglas Energy Solutions, we support organisations across the UK with Display Energy Certificate assessments and compliance requirements.
Our team works closely with clients to ensure the process is straightforward, efficient, and delivers meaningful insight into building energy performance.
If your organisation requires a new DEC, a renewal, or advice on improving energy efficiency, get in touch with our team today.