This 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.

This could can vary considerably depending upon the size and complication of the dwelling, however a typical cost range would be between £120 – £300. For those who also require an Energy Performance Certificate (EPC) at the end of it there may be a further charge of around £50 to register the EPC on the register. Special discounts would typically be available for a number of dwellings especially if they are of the identical style of building.

Before we get to the differences, here is what you will need 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 show the energy performance of a property. An EPC or Energy Performance Certificate is a overview report created from the Sap calculations which produces a SAP rating from 0 to 100. This rating is expressed on the EPC as A the highest to G the lowest. It will also list suggestions which would enhance the rating of your dwelling.

There are really 2 kinds of EPCs. First is a SAP EPC which is produced from building plans when all of the elements of the building are known. This will normally be required by building control to show that a dwelling meets specific targets essential to the building regulations. Building control would also need to see the SAP calculations which shows in greater detail whether all of the elements going into your property comply with the building regulations.

The second sort of EPC is the standard one that would be required when you are selling, or renting a property. This type of EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, which is used where certain thermal values of, for example, the walls, roof, floors, etc, usually are not precisely known on an existing property. In this instance assumed thermal values are used based on the age of your property. This type of EPC would be no good to show compliance with any building regulations. Sometimes building control would simply ask you for an EPC, however 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).

Still confused, then call us for additional advice.

These will be the finished set of SAP calculations created after the dwelling has actually been completed to hopefully demonstrate that it is compliant with Part L1A of the building regulations. Ahead of the project starting, it ought to have had some “Design Sap” calculations to show that the planned building, in theory at least, would be compliant with Part L1A.

No, this is not something that can be done yourself. Sap calculations have to be done by an On Construction Domestic Energy Assessor or OCDEA, using approved Government software programs. The Assessor needs to be approved under one of the accreditation 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)

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

It’s now fashionable to get large bi-folding doors, sky lights and large quantities of glazing on new extensions. However under the latest building regulations the amount of glazing must be no more than 25percent of the floor area of the new extension. So over compensations on the thermal elements in other areas within the property will need to be made to show that the CO2 emissions coming from the existing house along with the planned extension is not any worse when compared to the existing house and an extension whose glazing is within the permitted amount judged against Part L1B of the building regulations.

You will require SAP calculations to find solutions and illustrate compliance.

When you are 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 is not an exhaustive list. Give us a call, if you are not certain if you require them.