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

The average budget range will be between £100 – £300, this is depending upon the difficulty and size of the property. There may be an extra charge of about £50 if an Energy Performance Certificate is required at the end of the construction. For a number of properties of comparable types, then discounts could well be offered.

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 computations of pre defined data set of a buildings design that’s created to display the energy effectiveness of a building. An EPC or Energy Performance Certificate is a summary report created from the Sap calculations that 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 recommendations that would improve the rating of your property.

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

The second variety of EPC is the typical one that would be required when 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 certain thermal values of, for instance, the walls, roof, floors, etc, usually are not precisely known on an established property. In this instance assumed thermal values are used based on the age of the property. This kind of EPC would be no good to demonstrate compliance with any building regulations. Sometimes building control would simply ask you for 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 a summary report from the Sap calculations).

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

These will be the final set of SAP calculations created once the building has actually been completed to show that it is compliant with Part L1A of the building regulations. Ahead of the project starting, it should have had some “Design Sap” calculations to demonstrate that the proposed dwelling, on paper at least, would be compliant with Part L1A.

No, this is not something that can be done by yourself. The calculations must be carried out by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government computer software. The Assessor needs to be approved under one of several certification schemes and is 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 Sap calculations to show compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regs.

It’s now quite modern 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 must be no more than 25% 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 coming from the existing house and the proposed extension is no worse than the existing house and an extension whose glazing is within the allowed amount judged against Part L1B of the building regulations.

You will need SAP calculations to find solutions and show compliance.

For anybody who is modifying 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 list. If you’re unsure whether you require them, then simply contact us.