Proposed Changes to the Standard Assessment Procedure (SAP)

Date added: 24 February 2012

SAP is the only method of assessing a new dwellings energy performance and compliance under section 1 of the Building Regulations Part L1a.

The government's desire to ensure all new dwellings are zero carbon by 2016 means that changes to Part L and hence SAP are required. DECC are consulting on 5 main changes to SAP which are outlined below, while they are of obvious interest to SAP assessors builders and contractors should be aware of the potential changes to avoid being caught out by a simple or minor amendment.


Amendment 1 Carbon dioxide emissions factors

Inclusion of other greenhouse gas emissions specifically CH4 and N2O

Currently SAP only assesses CO2 emissions, including other gases will provide a fuller assessment of the environmental impact of energy use.

In addition the proposal is to include indirect and upstream emissions associated with the transportation of fuels including fuels produced outside of the UK.

Currently there is a weighting added to electricity exported to the grid from on site renewable generation. This weighting helps offset imported electricity and assists the dwelling in passing Part L. The proposal is to remove this weighting and have an even factor for both imports and exports of electricity.

The time period for which emission factors are calculated is currently 5 years, the consultation is seeking comments on whether this period should be shorter or longer.

The consultation suggests that the carbon associated with plant or animal sourced fuels (eg bio fuels, wood chip etc) would continue to be excluded.


Amendment 2 Use of regional weather data

Use of regional wind speed data and a revised method for calculating solar radiation based on orientation and pitch are proposed.


Amendment 3 Heating and hot water systems with boilers

Boiler efficiency tests to align with the European eco design regulations and heat losses from storage combi boilers to be introduced.

An adjustment to the benefit derived from time and temperature zone control, such controls have a reduced benefit for smaller dwellings and so the SAP calculation would reflect this.


Amendment 4 Insulation and extent of primary pipe work

This amendment is not scheduled for SAP 2012 but the suggestion is to measure the length of primary and secondary pipe work insulation and to enter the length insulated into SAP. Comments regarding this approach are invited by DECC.


Amendment 5 Default seasonal performance factors for heat pumps

As heat pumps have become more prevalent in the UK actual measured data has been gathered and analysed. The performance of heat pumps is slightly worse on average than the typical values currently used in SAP and so the amendment is to reduce the default seasonal performance figures within SAP. Default values would be able to be overridden by measured data whenever possible.

All of the above is a consultation by DECC and responses are invited. The full document and associated reports etc can be found at www.bre.co.uk/sap2012

MLM are available to discuss the implications of the proposed amendments with any clients who have concerns. Please contact our SAP assessor Iain Farquharson on 01473 231100 or iain.farquharson@mlm.uk.com

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