The Display Energy Certificate aims to encourage public building owners to adopt energy efficiency measures by displaying their energy performance.

What is a Display Energy Certificate

The Display Energy Certificate (DEC) rating is based on the measured, actual energy use of a building. This is then compared to a benchmark for similar buildings. In contrast, a BER is based on calculated energy use.

The certificate shows the grade awarded, energy and CO2 performance indicators, and your energy trends. It is required in addition to the BER and covers both privately and publicly owned large buildings.


Buildings requiring a DEC

  • a building other than a dwelling, which is occupied by a public body, has a total useful floor area greater than 250 m2, and is frequently visited by the public
  • a building other than a dwelling, which has a total useful floor area greater than 500 m2, and is frequently visited by the public

How a DEC is calculated

The DEC rating is calculated actual energy consumption over a one year period. This may include different fuel types, district heating and cooling, and electricity. Operational rating is calculated from meter readings or energy bills.

However, if you do not have sufficient billing data accumulated, a DEC can still be carried out using an estimate from your energy supplier.

A DEC must be updated every year to reflect energy-use trends.

Using benchmarks

Benchmarks are used to take local factors into consideration when calculating the DEC. Benchmarks include specific building use categories with standard use patterns, certain locations, and climate. Provisions are made where:

  • The building use covers more than one building use category
  • There is a significant climate difference between the building and the standard benchmark
  • The use periods of the building are significantly greater than the standard benchmark
  • Specific identified processes means that energy use is more intensive than usual for the building use category

Displaying a DEC

A hard copy of the DEC must be shown in a prominent place where it is visible to the public. Public bodies may also wish to show it on their website or other public facing media.

DEC assessors

A DEC must be completed by a DEC assessor registered with SEAI. Be sure to seek out more than one quotation.

Find a DEC Assessor

Resources for DEC Assessors

The guidance documents below are to assist DEC assessors in completing DEC assessments.


Contact us

Call 01 808 2054