An EPC rates the energy efficiency of a dwelling from A (very efficient) to G (inefficient). It will give you some indication of how costly the building will be to heat and light, and what its carbon emissions are likely to be. The EPC will also state what the energy-efficiency rating could be if improvements are made, and highlights cost-effective ways to achieve a better rating. An EPC must be provided to building control before they can issue a final completion certificate.
Standard Assessment Procedure (SAP) is the method used to determine a dwellings energy performance. SAP calculations must be carried out at the design stage prior to the commencement of works on site, and also at the completed “as-built” stage.
The Design SAP refers to the DER/TER (Dwelling Emission Rate/Target Emission Rate) Calculations. Using the plans and specification provided by the architect we will calculate the thermal performance of each building element. Thermal performance is expressed as 'U' values (the rate at which heat passes through the fabric of the building), the higher the 'U' value the greater the rate of heat loss. Using SAP compliant software we will input the building design and specification details. This software determines whether the proposed dwelling will meet the requirements of the Building Regulations with regards to the conservation of fuel and power.
The As Built SAP calculations are used to generate the EPC. However, If you have made any changes to the original design/ specification e.g. layout, materials used, air tightness test result etc. building control may request detailed As Built SAP report to ensure that the dwelling still falls within the “pass rate” energy rating. We will generate a new SAP calculation to reflect the results of the air tightness test and any variations to the original specification. On completion we will upload this data to the governments Domestic Central Register – Landmark.