Energy performance certificate
What the certificate is
Section titled “What the certificate is”A document summarising the energy performance of the building, placing it on a scale and presenting the main energy indicators.
Its purpose is comparability: so that a buyer or tenant gets a realistic picture of the likely energy consumption of the building.
When it is needed
Section titled “When it is needed”Typically:
- at the occupancy of a new building,
- on sale,
- on letting,
- in some cases on major renovation.
The specific cases and the exemptions are set by legislation, and they change from time to time.
How it relates to the design calculation
Section titled “How it relates to the design calculation”An energy calculation is made during design, demonstrating compliance with the requirements. The certificate, by contrast, relates to the finished building.
The methodology is shared, but the inputs can differ: the design works with the designed state, the certificate with the as-built state.
Which is why the as-built documentation has to be available. Handover documentation.
Who may produce it
Section titled “Who may produce it”A qualified professional, under the rules of professional practice.
What to know for a light gauge steel building
Section titled “What to know for a light gauge steel building”The input is the build-up
Section titled “The input is the build-up”The accuracy of the certification depends on how well the actual build-up is known. In a concealed structure it cannot be surveyed afterwards — only the documentation reveals it.
Accounting for the thermal bridges
Section titled “Accounting for the thermal bridges”The calculation has to include the thermal bridges of the steel frame. If the assessor is not given that data, the result is distorted.
Airtightness
Section titled “Airtightness”If a measurement result exists, it can improve the accuracy of the calculation.
The practical advice
Section titled “The practical advice”Hand over the data needed for certification in one package at the end of the project: build-ups, materials installed, services data, test records. The certification is then fast and accurate rather than working from estimates.
This is not legal advice
Section titled “This is not legal advice”The cases in which certification is required, and the methodology, change. On a specific matter the text of the legislation in force governs.