Publication of SAP 10.0

25 July 2018

BRE have published the new methodology for the new version of SAP (SAP 10.0), so that it can be compared against the current version (SAP 2012). The specification document can be downloaded at: https://bregroup.com/sap/sap10.

It should be noted that this version is not to be used for any official purpose - SAP 2012 continues as the compliance tool for Building Regulations until further notice.

The main changes are summarised below:

  • CO2 emission factors, primary energy factors and fuel prices, have been updated using the latest data available. The method to derive them is unchanged from SAP 2012 except for the fuel price attributed to electricity exported to the grid, which has been reduced to the electricity wholesale price.
  • The assumed heating pattern has been changed to a consistent daily pattern for all days of the week – previously a different pattern was used at the weekend.
  • Additional design flow (heat emitter) temperature options have been provided for heat pumps and condensing boilers, which affect their efficiencies.
  • Default heat pump efficiencies have been updated.
  • The calculation of hot water consumption has been adjusted to account for shower flow rate.
  • The treatment of mechanical ventilation system heat recovery and aerodynamic performance has been revised.

In particular, electricity's CO2 emission and primary energy factors have dropped by 55% and 43%, respectively, as per the table below.

 

Primary Energy Factor

Carbon Factor

SAP 2012

3.07 kWhth/kWhel

0.519 kgCO2/kWh

SAP 10 Consultation

2.364 kWhth/kWhel

0.398 kgCO2/kWh

SAP 10 draft

1.738 kWhth/kWhel

0.233 kgCO2/kWh

 

The new SAP values mean that, according to Government data [1], in 2017 electric heating will have been more carbon efficient than gas heating (assuming 100% system efficiency for electric heating with an emissions intensity at 0.212kg CO2/kWh versus 85% gas heating system efficiency with an intensity of 0.184kg CO2/kWh). Similarly, a heat pump only needs to have an annual COP of 1.1 to be more efficiency than gas heating (using the SAP 10.0 carbon factor for electricity for 2018-2020 and assuming 85% gas heating system efficiency with an intensity of 0.184kg CO2/kWh) [2],. Based on these calculations, it is easy to see how SAP, once implemented, is likely to have a significant impact on the specification of heating systems for new-build.

If you have any questions, please get in touch with [email protected].

[1] BEIS – Updated Energy and Emission projections (2017)

[2] The Government’s Standard Assessment Procedure for Energy Rating of Dwellings Version 10.0  (SAP 10.0)

Return to listing