Commercial EPC Conventions Issue 6

Please find below the documents forwarded by DCLG to all Non-Domestic Energy Accreditation Schemes to pass on to their Assessors:

"The conventions are designed to improve the quality and the accuracy of Commercial Energy Certificates. The conventions will, therefore, supersede any previous assessment process and previously published guidance. With this in mind, further conventions are being developed and will be released in stages".

Related files (referred to at the end of the letter)

Non Domestic EPC Conventions for Northern Ireland Issue 2.0: 17 January 2011

These conventions (Issue 2.0), will also apply to assessments in Northern Ireland (with a small modification at 2.03, 3.02 and 3.05 ) and must be applied by all NDEPC certified energy assessors. Please note that the 'new' conventions must be applied on the same date. For audit and management purposes, the conventions must be applied on the dates shown in the 'Implementation Date' column on the right-hand side of the table. These conventions will be included as part of future quality assurance checks of the assessments you have undertaken, and the EPCs you have produced, thereafter.

Table to be substituted at 2.03 for Northern Ireland in place of the England and Wales table.

2.03 Air permeability

The SBEM default value of 25 m3/hr m-2 for all existing buildings shall be amended as follows: 
Less than 10 m3/hr m-2 – only with an certified air pressure test result
15 m3/hr m-2 – buildings built to NI Building Regulations Part F 1999
25 m3/hr m-2 – buildings built to NI Building Regulations pre Part F 1999
35 m3/hr m-2 – to be considered where buildings are pre Part F 1999 regulations and where suitable evidence of high permeability exists, e.g. single skin metal clad structure within Planning Use Class B3 and B4 with large roller shutter doors and poor constructional details etc.

1st June 2010


Table to be substituted at 3.02 for Northern Ireland in place of the England and Wales table.

3.02 Adjacency assumed  - party walls

Unless evidence to the contrary is readily and easily available, all buildings adjoining that building or part building which is being assessed, are assumed to be conditioned unless they are of Planning Class B3 and B4 in which case they are assumed to be unconditioned.

1st June 2010


Table to be substituted at 3.05 for Northern Ireland in place of the England and Wales table.

3.05 Inadequate or no fixed building services in existing buildings.

Where there are inadequate or no fixed building services, in an existing building, the following guidance should be followed as appropriate. Note: where the building and fit out meet the first fit out definition in Technical Booklet F2 then the guidance in that document must be followed. The following guidance is therefore applicable only for existing buildings which have already had services installed and to which the term subsequent fit out would apply. 
1. Where there is clear physical evidence of a previous HVAC system then it is appropriate to select the same HVAC system as previously installed and to use the Non Domestic Building Services Compliance Guide (NDBSCG) to obtain suitable minimum efficiency values for the ‘Effective Heat Generating Seasonal Efficiency’ and where applicable the ‘Generator Seasonal Energy Efficiency Ratio’ (SEER) and ‘Generator Nominal Energy Efficiency Ratio’ (EER).
2. Where there is evidence that new services have been ordered or that they have been delivered but not installed then these will not be considered fixed building services and their detail will not be used in the EPC. The following assumed fit out guidance will be followed