This really is quite possibly the most common question asked. Take a look at Andrea’s video explanation above, or read the full explanation here on the right.

The average budget range is between £100 – £300, this is depending on the difficulty and proportions of your property. Should you also need an Energy Performance Certificate (EPC) at the end of it there may be an additional charge of about £50 to lodge the EPC on the national register. Special discounts would typically be available for multiple properties especially when they are of the same style 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 calculations of pre defined data set of a buildings design that’s put together to demonstrate the energy effectiveness of a dwelling. 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 shown on the EPC as A the highest to G the lowest. It will also list suggestions that would increase the rating of the property.

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

The 2nd variety of EPC is the standard one that will be necessary for anybody who is selling, or renting out a property. This particular EPC uses what’s called rdSAP, which stands for Reduced Data Standard Assessment Procedure, and is used where specific thermal values of, for instance, the walls, roof, floors, etc, are not precisely known on an established property. In this case assumed thermal values are used depending on the age of your property. This sort 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 to have are the Sap calculations (which is the information behind the EPC) and the SAP EPC (which is a summary report from the Sap calculations).

If you are still confused, after that call us to get more advice.

These are the finished set of SAP calculations produced once the building 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 a set of “Design Sap” calculations to show that the planned building, in theory at least, would be compliant with Part L1A.

Unfortunately this is not some thing that can be done by yourself. The calculations need to be done by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government computer software. The Assessor has to be approved under one of several accreditation schemes and is regularly audited to keep up 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 property 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 modern to get large bi-folding doors, sky lights and large amounts of glazing on new extensions. But with the latest building regulations the quantity of glazing can be no more than 25percent of the floor area of the new extension. So over compensations in the thermal elements in other parts of the property will need to be made to show the CO2 emissions coming from the existing house and the planned 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 will need SAP calculations to find solutions and demonstrate compliance.

When you are changing 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 unsure whether you will need them, then phone us.