Compiling an Energy Performance Certificate

A commercial EPC is prepared and issued by a trained and accredited energy assessor. However, a higher standard of qualification (up to NVQ level 4) is expected to be the norm for this discipline, compared with that required for domestic surveys. These higher standards reflect the greater size, diversity and complexity of commercial buildings, which range through all sizes of offices, industrial, retail, leisure and specialist premises.

The preparation of an energy certificate requires the collection and processing of a substantial amount of data. This information covers the following aspects of the building.

• Structure – the nature of the walls, floors, roof, windows and doors, basically so as to calculate their insulating properties.
• Layout - how the building is divided up into spaces, and how these spaces are used and separated from each other, either by outside walls or internal partitions. For the purposes of energy assessment, rooms, workshops or warehouses are often sub-divided into 'zones'.
• Services - The heating, lighting, air-conditioning and ventilation serving the building, together with the 'domestic' hot water, and any 'green' energy sources such as wind and solar power, heat recovery and the like.

All of this information is related back to the sub-division, or ‘zones’ of the building. The data is collected on the basis of the zones, with the dimensions, structure and services for each being recorded. The data is then entered into a complex computer model called SBEM. Current opinion is that the data entry could take as long as the survey. As an illustration, the ‘Example Building’ referred to in various presentations and tutorials is considered ‘simple’ and has around 500 data fields and inputs. Once the data is loaded, the modeling software calculates the energy rating for the building, and produces the energy performance certificate and recommendations for improvement..

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