What are SAP calculations and why are they so important?

What are SAP calculations and why are they so important?

The Standard Assessment Procedure (SAP) is a methodology introduced by the Government to assess and compare the energy and environmental performance of buildings to make sure that any new developments will not only meet Building Regulations, but also all energy and environmental policy initiatives.

The principle aim is to assess how much energy a new development will consume, when delivering a defined level of comfort and service provision using standard assumptions for occupancy and behaviour.

This process also standardises the assessments of dwelling energy performance so that like for like comparisons can be made nationwide.

How are SAP calculations made?

SAP calculations are based on the energy balance of a new development, considering a range of factors that contribute to energy efficiency, such as:

  • materials used for the construction

  • thermal insulation of the building fabric

  • air leakage characteristics of the dwelling, and performance of ventilation equipment

  • efficiency and control of the heating systems

  • solar gains through openings in the dwelling

  • the fuel used to provide space and water heating, ventilation and lighting

  • energy for space cooling

  • renewable energy technologies

The calculation does not include individual characteristics of the household such as household size and heating patterns and temperatures.

SAP calculations can also determine fuel costs and the Environmental Impact Rating via the emissions of carbon dioxide (CO2).

Why are SAP calculations important? 

SAP assessments have been a legal requirement for all new-build, domestic properties in the UK under Part L of Building Regulations since 1995. Homes must achieve a ‘Pass’ on these calculations for the project to pass Building Regulations.

Without this, a property will not be signed off by Building Control and may not legally be listed for rent or sale.

As so many of the elements of the assessment are related to the construction of the development, it is strongly advised that the SAP scores are calculated and considered at the beginning of the project in order to best inform architects, builders, surveyors and suppliers. Achieving a pass on the SAP calculation can involve numerous important initial design decisions.

Alongside the regulatory aspect, there are other reasons why it is vitally important to consider your SAP score long before project completion. Factors such as energy consumption and carbon output can be accurately predicted and the running costs of the home minimalised from an early-stage professional SAP assessment.

Is this just for new developments?

SAP Assessments are not confined to just new developments. New extensions or conversions may require a SAP Assessment under Part L1b of the Building Regulations, based on the following guidelines:

  • Extensions with more than 25% glazing-to-floor area

  • Barn conversions

  • Commercial to domestic conversions

  • Conversion of a single dwelling into flats or apartments


Need help with a SAP Calculation pass?

Unfortunately, there is no set formula for achieving a SAP Pass as there are so many elements to be considered.

At Energytest we carry out SAP Calculations every day and by involving one of our trained consultants in the initial planning stages, we can help develop the project so that not only do you get the house you want, but that it meets all Building Regulation and environmental guidelines.