Approved Document L1A & L1B - SAP Calculations and EPCs

SAP stands for Standard Assessment Procedure and is a method of calculating the energy efficiency and energy use of a dwelling. It is from this calculation that an Energy Performance Certificate (EPC) is created. An EPC is required for every new build and refurbished property, and a design stage SAP assessment is needed to be signed off by building control before you start on site.

MACH Energy offers fully accredited ‘design stage’ and ‘as built’ SAP assessments, as well as EPCs for either new (Part L1A) or refurbished (Part L1B) dwellings. The MACH service ensures that you will not just receive a pass or fail mark, but will be offered pragmatic and detailed advice on how to improve the design, with input on the varius methods on how this can improvement can be carried out.

Get in touch if you are looking to get a quote for your project or just have some questions about which performance targets apply to your project.

SAP Calculations

Do you need a SAP assessment and EPC for your project?

Call 0117 944 1388 or email Josh Childs at

Design Stage SAP Calculations

SAP calculations are carried out early on in the design stage to ensure that the proposed dwelling is in line with the requirements set out within Approved Document L1A or L1B.

If the current design falls short of these requirements, MACH will give advice on how to improve the performance, such as through improving the u-values of the building fabric, by improving the efficiency of the heating system, or by introducing renewable energy sources within the development.
Note that a compliant Design Stage Assessment will need to be signed off by Building Control before work can start on site.

As-Built SAP Calculations and EPC Issue

Upon completion of a project, a final SAP assessment will be carried out that incorporates any changes in the design that occurred over the construction stage, as well as the specific boiler make and model and the measured air test results.
From this, the final energy efficiency performance will be determine and an EPC will be produced. This EPC is needed for submission to building control for the last part of Approved Document L1A & L1B to be signed off.

What Is Needed to Carry Out The Assessment?

We will require the following to provide an As-Built Assessment and EPC:
  • Floor plans, section drawings, elevations and site plan
  • Details of wall, floor, roof, door and glazing construction specifications
  • Mechanical and electrical specification (such as heating and ventilation systems)
  • Air test results (for new build properties)
  • Renewable technology specifications (such as photovoltaic panels or solar thermal panels)

Ask For A quote

Get in touch  to ask for a quote for a SAP Assessment.
Please also see our list of required information for SAP calculations, which helps make the process quicker and smoother

SAP Calculations
SAP Calculations
0117 944 1388