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

The typical cost range is between £100 – £300, this can be depending on the difficulty and size of the property. There may be an additional charge of approximately £50 if an Energy Performance Certificate is called for at the end of the build. Reductions would typically be available for multiple properties especially if they are of the identical type of structure.

Before we explain the difference, 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 computations of pre defined data set of a properties design that’s created to demonstrate the energy effectiveness of a building. An EPC or Energy Performance Certificate is a summary 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 your property.

There are really two kinds of EPCs. The first is a SAP EPC that is created from building plans where all of the components of the building are known. This would normally be needed by building control to show that the property satisfies certain targets essential to the building regulations. Building control would also have to see the SAP calculations which shows in greater detail whether the many elements going into the property conform to the building regulations.

The second type of EPC is the regular one that would be necessary if you are marketing, or renting out a property. This sort of EPC uses what’s called rdSAP, which is short for Reduced Data Standard Assessment Procedure, and is used where specific thermal values of, for example, the walls, roof, floors, etc, are not precisely known on an existing property. In this instance assumed thermal values are used based on the age of the property. This sort of EPC will be no good to show compliance with any building regulations. Sometimes building control would simply ask you to get an EPC, but what they would really need 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 perplexed, then phone us for further advice.

These are the finished set of SAP calculations produced once the dwelling has actually been completed to hopefully demonstrate that it is compliant with Part L1A of the building regulations. Prior to the project starting, it ought to have had a set of “Design Sap” calculations to show that the planned construction, in theory at least, will be compliant with Part L1A.

No, this is not some thing that you can do yourself. Sap calculations need to be carried out by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government software programs. The Assessor needs to be certified under one of the certification schemes and is also regularly audited to maintain their qualification.

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 modern to get large bi-folding doors, sky lights and large quantities of glazing on new extensions. But with the present building regulations the quantity of glazing can be a maximum of 25% of the floor area of the new extension. So over compensations in the thermal elements in other places of the property will have to be made to show that the CO2 emissions coming from the current house along with the planned extension is not any worse when compared to the existing house and an extension where the glazing is within the allowed amount judged against Part L1B of the building regulations.

You need SAP calculations to find solutions and demonstrate compliance.

For anybody who is altering the use of a dwelling, 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 checklist is not exhaustive. If you’re not sure whether you will need them, then phone us.