This is by far the most common query asked. Have a look at Andrea’s video explanation above, or read the full explanation here on the right.

The typical price range can be between £100 – £300, this can be depending upon the difficulty and size of your property. There may be a further charge of approximately £50 if an EPC is called for at the end of the construction. For several dwellings of similar types, then special discounts might be available.

Before we get to the differences, this is what you will require depending on your job.

For a new build property you’ll need – SAP calculations and an EPC.

For dwelling change of use or conversion you’ll need – Sap Calculations and an EPC.

For overglazing on an existing dwelling you’ll – Sap calculations only.

SAP or Standard Assessment Procedure are the calculations of pre defined data set of a buildings design that’s put together to display the energy efficiency of a property. EPC means Energy Performance Certificate and it’s a summary report of the SAP calculations in an simple to comprehend report, that could also be used to sell or rent a property.

There are really 2 kinds of EPCs. The first is a SAP EPC which is produced from building plans when all the components of the construction are known. This would normally be required by building control to show that a property satisfies specific targets required by the building regulations. Building control would also need to see the SAP calculations which illustrates in detail whether all the components going into your property comply with the building regulations.

The 2nd form of EPC is the typical one that will be required for anyone who is marketing, or renting out a property. This particular EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, and is used where specified thermal values of, for example, the walls, roof, floors, etc, usually are not precisely known on an existing property. In this case assumed thermal values are used according to the age of your property. This particular EPC will be no good to show compliance with any building regulations. Sometimes building control would simply ask you for the EPC, however what they would really need to have are the Sap calculations (which is the data behind the EPC) and the SAP EPC (which is a summary report of the Sap calculations).

Still confused, then phone us to get more advice.

These will be the final set of SAP calculations produced once the building has actually been completed to confirm that it is compliant with Part L1A of the building regulations. Ahead of the construction starting, it ought to have had a set of “Design Sap” calculations to show that the planned construction, on paper at least, will be compliant with Part L1A.

No, this is not some thing that you can do yourself. The calculations have to be done by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government computer software. The Assessor has to be certified under one of the certification schemes and is also regularly audited to keep their certification.

Your Assessor would advise you of exactly what is needed. Typically you would need the following:

• Floor Plans to include sections and elevations
• Orientation of the property
• Construction specification of walls, roof and floors
• Specification for all doors and windows
• Primary and secondary heating
• Provision for providing  hot water
• Any renewable technology (if any)

All new property need to have Sap calculations to show compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regulations.

It’s now popular to have large bi-folding doors, sky lights and large amounts of glazing on new extensions. However with the present building regulations the amount of glazing must be a maximum of 25% of the floor area of the new extension. So over compensations on the thermal elements in other places within the property will need to be made to demonstrate that the CO2 emissions coming from the existing house and the planned extension is no worse than the existing house and an extension whose glazing is within the permitted amount judged against Part L1B of the building regulations.

You need SAP calculations to find solutions and show compliance.

For anyone who is changing the use of a building, you will require Sap calculations. {The new dwelling will have to comply with Part L1B of the building regulations.}

You will need Sap calculations for any of the following: 

• Building a new property
• Changing the use of an existing property (e.g, a barn conversion, commercial building to residential)
• Extensions with more than 25% glazing
• Opening up the main house to an existing conservatory
• Extension where the extension is more than 50% of the original property wall area
• Garage conversions
• If requested by building control

This is not an exhaustive list. Contact us, if you are not certain if you need them.