The hardest part of a Display Energy Certificate is often finding the right numbers, not finding a certificate template. A DEC measures a qualifying public building's operational energy use against a benchmark. If the meter list is incomplete, the accounting period is unclear or a shared supply crosses building boundaries, the assessor has to investigate before a reliable rating can be produced.
Choose one building and one annual period
Start with the address, floor area, main use and spaces included in the assessment. Then build a schedule of all energy supplies serving that building. The operational rating uses energy consumed over an annual period of 365 days; ideally, the different fuels cover the same dates. Record start and end readings, units, meter identifiers and where each supply enters the building. A utility bill is useful, but note when it is estimated rather than based on an actual reading.
Look beyond the electricity and gas accounts
A public estate may also use oil, solid fuel, district heating or cooling, privately distributed electricity, or generation on site. Gather delivery notes and provider statements where a normal utility bill does not exist. Solar generation and exports need clear records so the assessor can apply the approved methodology correctly. Ask the landlord, facilities team and energy supplier for missing records early; do not silently omit a fuel because the invoice belongs to another department.
Flag shared meters and unusual operations
Write down any supply that serves another building, a tenant area or a separately managed facility. Also note opening hours, major vacancies, refurbishments and changes in use during the period. The methodology allows certain adjustments, but only the accredited DEC assessor can decide whether they apply and what evidence is needed. A clear meter map and a short explanation of anomalies are more useful than an unexplained spreadsheet total.
Turn the certificate into a useful baseline
Keep the source data, calculation period and previous DEC together for the next renewal. The accompanying advisory report can then be considered alongside the building's actual operating pattern, rather than treated as a generic shopping list. A facilities manager who can trace each figure back to a meter or supplier record is in a stronger position to discuss both the operational rating and practical energy improvements. Our Display Energy Certificate service can scope the records needed for your building.