What are SAP Calculations?

SAP stands for Standard Assessment Procedure. It is the only official, government approved system for assessing the energy and environmental performance of a new dwelling. SAP Calculations are required before commencing work on any new build dwelling, whether houses, flats, conversions (i.e. offices to residential). Some extensions will also require a SAP Calculation, depending on the amount of glazing.

SAP Calculations are based on the predicted energy use and resulting carbon dioxide emissions of a dwelling over the course of a year taking into account a range of factors that contribute to energy efficiency. They are based on a standardised assumptions of occupancy and behaviour to enable a like-for-like comparison. The energy cost is based on the construction of the dwelling, its heating system, internal lighting and any renewable technologies installed. It does not include energy used for cooking or appliances.

What do SAP Calculations do?

  • They determine a SAP rating (the energy related running costs of a dwelling)

The SAP rating is a figure between 1 and 100+ (100 represents zero energy costs and anything over 100 means energy is exported). The higher the SAP rating, the lower the fuel costs and the lower the associated emissions of carbon dioxide. The rating provides a way of comparing the energy performance of different homes.

In addition to the SAP rating they are used to provide the following information for a dwelling:

  • The Target Emissions Rate (TER)
  • The Target Fabric Energy Efficiency (TFEE)
  • The Dwelling Emissions Rate (DER)
  • The Dwelling Fabric Energy Efficiency (DFEE)

Note: Wales and Scotland have a different system, where only the DER is measured, however, the building regulation standards are stricter.

  • They demonstrate compliance with Part L of the Building Regulations

SAP Calculations are used as the main compliance tool for Building Regulations Part L1A and Part L1B. House builders/developers need to achieve a ‘PASS’ on their SAP Calculation, if they ‘FAIL’ or don’t have a SAP Calculation Building Control will not sign off the building works/development and the property cannot be marketed for sale or let.

  • They are used to produce an Energy Performance Certificate (EPC)

An EPC is required by law to rent or sell a residential property.

When are SAP Calculations carried out?

A SAP assessment is carried out at two stages in the design and construction of a new dwelling, conversion and in some cases extensions. These are:

  • At Design Stage, with a submission to Building Control before work starts on site
  • At As Built Stage, with a final submission on completion of the dwelling

The two submissions can be used by Building Control to check compliance with required targets in the Building Regulations Part L1A and Part L1B. A clear connection must be evident between product specifications and the data inputs into the SAP software. The As Built submission is required to produce the Energy Performance Certificate (EPC) for the completed dwelling.

Eden SAP Services recommend carrying out your SAP Calculations as soon as possible at a design stage, or even at tender stage as this will help identify the specification and review options to help assist with costing of the project.

Who can provide a SAP Calculation?

SAP Calculations are undertaken via approved software packages by SAP assessors (On Construction Energy Assessors) who must be accredited and registered with a certification body. The latest version of the SAP document is SAP 2012.