This really is quite possibly the most frequent query asked. Check out Andrea’s video explanation above, or read the full explanation here on the right.

The average cost range will be between £100 – £300, this is depending upon the difficulty and proportions of the property. There will probably be another charge of around £50 if an EPC is required at the end of the build. For a number of dwellings of comparable designs, then discounts would be available.

Before we explain the difference, here is what you will require 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 calculations of pre defined data set of a buildings design that’s put together to display the energy effectiveness of a dwelling. An EPC or Energy Performance Certificate is a summary report created from the Sap calculations that produces a SAP rating from 0 to 100. This rating is shown on the EPC as A the highest to G the lowest. It will also list suggestions which would increase the rating of your property.

There are really 2 types of EPCs. First is a SAP EPC that is produced from building plans when all the elements of the construction are known. This will normally be needed by building control to demonstrate that a property complies with specified targets essential to the building regulations. Building control would also have to see the SAP calculations which shows in detail whether all of the components going into the property comply with the building regulations.

The 2nd variety of EPC is the regular one that will be needed when you are marketing, or renting out a property. This kind of EPC uses what’s called rdSAP, which means 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 established property. In this instance assumed thermal values are used depending on the age of the property. This sort of EPC will be no good to demonstrate 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 of the Sap calculations).

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

These will be the final set of SAP calculations generated when the building has actually been completed to confirm that it is compliant with Part L1A of the building regulations. Prior to the building starting, it ought to have had some “Design Sap” calculations to demonstrate that the proposed dwelling, on paper at least, will be compliant with Part L1A.

No, this is not something you could do by yourself. The calculations must be carried out by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government program. The Assessor has to be approved under one of several certification schemes and is regularly audited to keep up 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)

Every new property 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 trendy to get large bi-folding doors, sky lights and large amounts of glazing on new extensions. However with the latest building regulations the quantity of glazing can be a maximum of 25percent of the floor area of the new extension. So over compensations on the thermal elements in other places within the property will have to be made to show that the CO2 emissions from the existing house and the proposed extension is not any worse when compared to the existing house and an extension whose glazing is within the allowed amount judged against Part L1B of the building regulations.

You need SAP calculations to find solutions and illustrate compliance.

For anyone who is altering the use of a building, 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 is not an exhaustive checklist. If you’re uncertain whether you need them, then give us a call.