The Display Energy Certificate (DEC) aims to encourage the owners of public buildings to adopt energy efficiency measures by displaying their energy performance.

How a DEC is calculated

A DEC Assessor calculates the DEC rating using actual energy consumption over one year. This may include different fuel types, electricity and district heating and cooling. Operational rating is calculated from meter readings or energy bills.

If you don't have enough billing data, a DEC can be carried out using an estimate from your energy supplier. A DEC must be updated every year to reflect energy-use trends.


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

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 mean that energy use is more intensive than usual for the building use category.

DEC Calculator

The DEC calculator is accessed via a web-based application which is used by registered DEC assessors.

Find a DEC Assessor

Guides and manuals

These guidance documents help DEC assessors complete DEC assessments.

DEC Technical Manual

This manual details the methodology adopted in Ireland for calculating Display Energy Certificates (DEC) for public buildings

DEC User Guide

This user guide describes the calculation tool for calculating display energy certificates (DEC) for public buildings.


Technical support

You'll find a wide range of technical support for BER Assessors in this section. We recommend that you check this section before contacting the BER Helpdesk.

Technical support for BER assessors

BER Helpdesk

Call: 01 808 2029