We are often asked what the difference is between an EPC for a new building, and one for an existing building.


A SAP EPC refers to an Energy Performance Certificate issued by an ‘On Construction Domestic Energy Assessor’, using SAP methodology and software.

Any new dwelling, or dwellings created by conversion or change of use are required to have SAP Calculations carried out. The assessor will then in turn produce an EPC outlining the energy efficiency of that build.

The assessor will use architects plans and drawings, together with detailed information around construction, heating and ventilation amongst others.

EPC’s  for Existing Dwellings

Most EPC’s are required for existing dwellings as they are either being sold or let. This EPC would have previously gone into the Home Information Pack for prospective buyers or tenants to view however HIP’s have since been disgarded.

A Domestic Energy Assessor will visit the property, and using RDSAP (Reduced Data SAP) methodology will create the EPC.

The two versions of EPC are fundamentally the same thing, providing a picture of the energy efficiency and energy costs of the dwelling.

Generally an EPC for an existing dwelling will be less expensive to purchase than one derived from SAP Calculations.

Would you like to discuss your project?

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“Build Energy have been a joy to work with and we have been continually impressed with their responsiveness, proactivity and impressive turn-around times in ensuring that our projects achieve the required performance parameters – all with a friendly single point of contact. We have benefitted from Build Energy’s expert technical advice throughout the design and construction stages through to completion, helping us meet and exceed stringent building regulations requirements. We look forward to continuing our productive relationship in future projects.”

Alex Zimmermann

Wimshurst Pelleriti