SAP Calculations
For Conversions

Conversion Projects & Change Of Use (Part L1b)

Under Part L1b of the building regulations you are required to provide a SAP calculations when converting an existing non-domestic building into a residential dwelling or property. This is commonly known as "change of use". Typical scenarios include barn conversions, converting offices, shops and any other commercial building into a residential property.

The purpose of the SAP calculation is to demonstrate that the existing buildings insulation will provide adequate thermal properties to the occupants where previously the building use didn't require. Typically in barn conversions this may require the existing walls, floors and roofs to be insulated. For existing shops and offices this may require little to no changes in the insulation dependant on the age and construction of the building.


The requirements for conversion project aren't a strict as new build standards and allow for existing elements of the building to be incorporated into the design.

Upon completion of a dwelling the SAP calculation is used to prepare the Energy Performance Certificate (EPC).

Why Use BEAT?

  • Experienced and qualified assessors providing bespoke low cost solutions saving you money and time

  • We have preformed hundreds of assessments just like yours

  • Fast turnaround times

  • Reports in pdf format 

  • A dedicated assessor from start to finish

When should I get my Conversion SAP?

Quite simply, the earlier we are involved, the more influence we can have on easily incorporating small changes with minimal cost which can make big impacts and huge savings in build cost and carbon.

How long does it take to get a Conversion SAP calculation?

Generally a SAP calculation takes about 2-3 days to produce, we suggest however you allow 1 week from appointment to allow for busy periods.

What do you need to produce a SAP?

We require drawings including plans, sections, elevations and site plan together with a proposed specification for the materials and insulation together with the heating and hot water appliances.

What happens if my design fails?

Even if your proposed design and specification fails we will provide you solutions and recommendations to successfully achieve a PASS free of charge!

How to get a quote?

Just send us your project drawings via email to or use our quote request form and we'll send you an electronic quote by return.

Frequently Asked Questions