Energy Performance Certificates and representative sampling: guidance

Guidance on Energy Performance Certificates (EPCs) production for existing dwellings using representative sampling, EPC-07.

This guidance note provides advice for Approved Organisation (AO) members on the production of Energy Performance Certificates (EPCs) for dwellings, with particular relevance to the social housing sector. This replaces the guidance issued on 25 February 2009.

EPC production

Production of EPCs for existing dwellings must be carried out using the most recent version of RdSAP software. The data required to carry out an RdSAP calculation can be gathered in one of two ways:

  1. Survey of the dwelling
  2. Use of existing information and action to validate the accuracy of such information.

This note discusses requirements for assessors adopting the second option.

Previous practice

Under the original Directive, Article 7 noted that: "Certification for apartments or units designed for separate use in blocks may be based on a common certification of the whole building for blocks with a common heating system, or on the assessment of another representative apartment in the same block".

Accordingly, the practice of 'cloning' or 'representative sampling' of dwelling EPCs was permitted, whereby EPCs could be produced using information already held. This was particularly relevant to social housing providers where extensive data on their stock was available.

Current requirements

Changes to European legislation, the "recast" of the Energy Performance of Buildings Directive places a greater emphasis on the competence of assessor (Article 17 - Independent experts) and the quality of energy assessments (Article 18 - Independent control system).

Article 11(7) of the EPBD now notes that "Certification for single-family houses may be based on the assessment of another representative building of similar design and size with a similar actual energy performance quality if such correspondence can be guaranteed by the expert issuing the energy performance certificate".

Whilst this continues to allow a representative approach, the need for "correspondence to be guaranteed" does introduce a greater focus on validation of the data used in the calculation.

To this end, we would note that there is no barrier to the production of EPCs using data which is not gathered by a survey for that specific purpose. However, to ensure that EPCs produced using 'representative existing data' are accurate, it is necessary to ensure that the data used in the RdSAP calculation is verified by a visit to each dwelling to be certified. Dependent upon the quality and comprehensiveness of the existing data, such a visit would not be as exhaustive as a full survey but would require the assessor to verify any data items that are either unrecorded or potentially subject to change.

Questions and answers

  1. I have gathered information recently. Do I need to revisit the property to check data again?

Not always. It is possible that verification of existing data may be discharged by a recent visit to the property rather than having to arrange a separate visit for that specific purpose. This would require that all the data elements required for RdSAP can be shown to have been validated by such a prior visit.

However, in determining this, the assessor should record the grounds to support such an approach and also be aware that the longer the time between the last visit to a dwelling and EPC assessment, the greater the risk that elements may have changed, albeit this may require assessment on a case by case basis.

  1. Are there any circumstances where an assessor can issue an EPC without having visited the property?

No. A visit is essential to verify that data used is representative (see 1 above).

  1. Do I need to keep records specific to each assessment?

Yes. As with any EPC produced as a result of a survey for that specific purpose, the assessor will require to retain a record of the data used for the calculation together with evidence to verify that that data is representative of the building. We would suggest that a survey checklist adapted for this purpose would assist in record keeping.

  1. Article 11(7) of the Directive only covers houses. How should I assess flats?

Article 11(6) allows that certification of building units (which includes flats) may be based on the assessment of another representative building unit with the same energy-relevant characteristics in the same building". For consistency across dwelling types, the provisions for houses under 11(7) should also be applied to other dwelling types (flats and maisonettes).

  1. If an EPC has been produced, does it have to be replaced?

No. EPCs are valid for a period of 10 years and need only be updated if the building owner wishes to do so. As of 9 January 2013, the Scottish Government will require AOs to undertake sample checking of a statistically representative sample of EPCs as outlined in the Operational Framework agreement (published online at: insert link). Sample checking will, in effect, repeat the RdSAP calculation process using recorded data to verify that sufficient evidence was gathered and that correct process was used.

It is therefore essential that assessor records identify both the appropriate level of information (to allow an auditor to rerun the RdSAP EPC from source data) and also that the EPC was produced using representative existing data (to enable the appropriate investigations to be made where such EPCs are selected for audit).

More information

We also produce a number of other EPC guidance documents that deal with specific issues:




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