This really is quite possibly 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 is between £100 – £300, that is depending on the complexity and size of your property. There may be a further cost of about £50 if an Energy Performance Certificate is needed at the end of the build. Special discounts would typically be available for multiple properties especially if they are of the identical type of construction.

Before we get to the differences, here is what you will need depending on your project.

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 computations of pre defined data set of a buildings design that’s created to display the energy performance of a property. An EPC or Energy Performance Certificate is a overview report produced by the Sap calculations which produces a SAP score from 0 to 100. This score is expressed on the Energy Performance Certificate as A the highest to G the lowest. It will also list suggestions that would increase the rating of the property.

There are actually two types of EPCs. The first is a SAP EPC which is produced from building plans when all of the components of the construction are known. This will normally be needed by building control to demonstrate that a dwelling meets specified targets required by the building regulations. Building control would also have to see the SAP calculations which shows in detail whether all the components going into your property comply with the building regulations.

The second variety of EPC is the common one that would be required for anybody who is selling, or renting out a property. This kind of EPC uses what’s called rdSAP, which stands for Reduced Data Standard Assessment Procedure, and is used where particular thermal values of, for instance, 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 use to demonstrate compliance with any building regulations. Sometimes building control would simply ask you to get an EPC, but what they would really need to have are the Sap calculations (which is the data behind the EPC) and the SAP EPC (which is actually summary report from the Sap calculations).

If you are still confused, then simply call us for additional information.

These are the final set of SAP calculations produced after the dwelling has been completed to hopefully demonstrate that it is compliant with Part L1A of the building regulations. Prior to the construction starting, it ought to have had a set of “Design Sap” calculations to demonstrate that the proposed construction, on paper at least, will be compliant with Part L1A.

Unfortunately this is not something that you can do yourself. Sap calculations must be carried out by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government computer software. The Assessor must be approved under one of the certification schemes and is also regularly audited to maintain their accreditation.

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 dwelling need to have Sap calculations to prove compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regs.

It’s now quite fashionable to have large bi-folding doors, sky lights and large amounts of glazing on new extensions. But under the existing building regulations the quantity of glazing must be a maximum of 25% of the floor area of the new extension. So over compensations in the thermal elements in other parts within the property will need to be made to demonstrate that the CO2 emissions from the current house and the proposed extension is no worse when compared to the existing house and an extension where the glazing is within the permitted amount judged against Part L1B of the building regulations.

You should have SAP calculations to find solutions and demonstrate compliance.

If you are changing the use of a dwelling, you will need 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 checklist is not exhaustive. Give us a call, if you are uncertain if you need them.