This is certainly by far the most common question asked. Have a look at 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 on the complexity and size of your property. There may be a further charge of around £50 if an EPC is called for at the end of the build. Special discounts would typically be available for a number of dwellings especially if they are of the same style of building.

Before we explain the difference, 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 efficiency of a property. EPC means Energy Performance Certificate and it’s a summary statement from the SAP calculations in an easy to understand document, that could also be used to market or rent out a property.

There are actually two types of EPCs. The first is a SAP EPC that is created from building plans where all the components of the building are known. This will normally be needed by building control to demonstrate that a property meets specified targets required by the building regulations. Building control would must also see the SAP calculations which illustrates in detail whether all of the components going into your property conform to the building regulations.

The 2nd form of EPC is the regular one that would be necessary for anybody who is selling, or renting out a property. This type of EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, which is used where particular thermal values of, for instance, the walls, roof, floors, etc, are not precisely known on an existing property. In this case assumed thermal values are used based on the age of your property. This particular EPC will be no use to demonstrate compliance with any building regulations. Sometimes building control would simply ask you for the EPC, but what they would really need to have are the Sap calculations (which is the information behind the EPC) and the SAP EPC (which is actually summary report from the Sap calculations).

If you are still perplexed, after that call us for further assistance.

These are the finished set of SAP calculations generated when the dwelling has actually been completed to confirm 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 demonstrate that the planned building, on paper at least, will be compliant with Part L1A.

No, this is not some thing that you can do yourself. Sap calculations need to be done by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government software programs. The Assessor needs to be certified under one of several accreditation 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 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 trendy to get large bi-folding doors, sky lights and large amounts of glazing on new extensions. However under the latest building regulations the quantity of glazing can be no more than 25% of the floor area of the new extension. Therefore over compensations on the thermal elements in other places within the property will need to be made to show the CO2 emissions coming from the existing house along with the planned extension is no worse than the existing house and an extension whose glazing is within the permitted amount judged against Part L1B of the building regulations.

You should have SAP calculations to find solutions and illustrate compliance.

If you are modifying the use of a dwelling, 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. Call us, if you are not certain if you require them.