Glossary

Display Energy Certificate (DEC):
This describes a building’s actual energy performance as opposed to its theoretical performance (theoretical performance forms part of an EPC, see below). A DEC is sometimes referred to as its operational rating (whereas an EPC is sometimes referred to as an asset rating). 12 months worth of utility bills are necessary for a DEC, which is always accompanied by an advisory report that lists cost effective measures to improve the energy rating of the building. DECs are required for buildings that contain public sector occupiers, that provide a public service and has a floorspace greater than 1,000 sq m. DECs are valid for 1 year whereas the accompanying report is valid for seven years.

Energy Performance Certificate (EPC):
EPCs are produced using standard methods with standard assumptions about energy usage, so that the energy efficiency of one building can be compared to others. EPCs describe a building’s theoretical, as opposed to actual, energy performance, assuming standard usage, based on its construction geometry, materials and its heating, ventilation, cooling and lighting plant. An EPC is valid for up to 10 years and is always accompanied by a recommendation report that lists measures to improve the energy rating of a building. The certificate is accompanied by information about the rating that can be achieved if all recommendations are implemented.

Embodied energy:
Embodied energy is a measure of the quantity of energy bound into a building due to the extraction and processing of raw materials, in addition to manufacturing composite items and transporting the finished materials. According to the British Council of Offices, the energy embodied in new construction and renovation each year accounts for about 10% of UK energy use.

Green buildings:
Green buildings refers to buildings that show greater than average resource and energy efficiency, either in terms of the embodied energy bound up in the building itself, or else in the metered energy consumption of the building in use. The term green buildings is a narrower definition than the term sustainable building.

Operational Rating Certificate (forms one half of an Energy Performance Certificate):
This measures a buildings actual energy performance based on metered consumption.

Simplified Building Energy Method (SBEM):
SBEM is the methodology developed by BRE (Building Research Establishment) to calculate the minimum carbon performance standards of all new commercial buildings in the UK. The primary output from this tool is the calculated carbon emissions from the buildings based on standard occupancy and operational patterns. This is then converted into an energy performance rating.

Sustainable building:
The term sustainable building is a wider term than the term green building. It encapsulates the concept of the economic, environmental and social aspects of designing, operating, maintaining and occupying a building, both in the short term and the longer term.