"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 Approved Document L2A 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."