Building regulations have come under the spotlight over the last few months and it is generally accepted that some regulations are in need of an urgent review. On a positive note, it is therefore welcoming to read the recently published recommendations on the Standard Assessment Procedure (SAP) (the UK methodology for assessing the energy and environmental performance of homes) and that Government has accepted that how we assess the energy performance of homes needs to change if we are to keep pace with research, innovation and technology developments. 


In November 2016, the department for Business, Energy & Industrial Strategy (BEIS) released a consultation document containing 19 proposed amendments to the Government’s Standard Assessment Procedure (SAP). The consultation ran from 9th November 2016 until the 31st January 2017 during which period comment was welcomed in relation to the proposed changes.  

SAP is the methodology used to assess the energy performance of residential dwellings and thereby helps in delivering a number of the Government’s energy and environmental objectives. It has a fundamental role in driving energy savings at household and national levels, and it underpins modelling for policies that drive carbon savings and bill reductions. For new dwellings, SAP is also the vehicle for demonstrating compliance with Part L of Building Regulations, giving it a vital role in the Government’s efforts to improve our housing stock.

SAP was last updated in 2012 with the changes being implemented on projects from April 2014.  The assessment approach is periodically reviewed to ensure that it keeps pace with research, innovation and technology developments within the industry.

A summary of the 2016 consultation responses was recently released outlining the measures proposed for inclusion in the next revision of SAP. Three of the key amendments being proposed are:

  • An update of the carbon emission factors
  • Treatment of thermal bridges
  • Hot water methodology

Carbon Emission Factors

Emission factors in SAP are used to calculate carbon emissions in order to demonstrate compliance with Part L. Under the new proposals the carbon emission factor for electricity is due to fall by 23%. A decrease in the proportion of electricity generated from coal and an increase in the amount of renewable energy available are reasons cited for this change.  This change in emission factor will see heating and hot water technologies using electricity perform more favourably within the calculation than with previous versions of SAP. In theory, this means that Part L compliance will be easier to achieve when using electric space and water heating technologies, however the emission factor for electricity is still significantly higher than mains gas upon which the Target Emission Rate (TER) target is set.

Treatment of thermal bridges

Non-repeating thermal bridges occur at junctions where opaque elements meet, such as a wall and a floor. Heat losses through these parts of a residential building are captured in SAP through individual psi values and across the building as a whole through the y value. At present, SAP has a set of approved psi values that can be applied when buildings are constructed in line with published Accredited Construction Details (ACDs). Under the current proposals, the ACDs will no longer be permitted for use within SAP and the default y value will be increased from 0.15 0.20. Once ACDs can no longer be used within SAP, greater consideration will need to be given to what calculated psi values are available within the industry, relative to the chosen project construction type. The use of the default y value or default junction values within SAP will not enable the SAP Calculation to comply with the target fabric energy efficiency target (TFEE) and fail Part L. Construction methodologies outside of traditional cavity wall and timber frame will need to consider specifically calculated psi values early in the design process to ensure compliance with TFEE and Part L are achieved.

Hot water Methodology

A daily hot water requirement for water used in showers, baths and other uses, in litres / day, is to be included within the SAP calculation. Currently water use is considered but only in relation to Part G and not Part L. The new proposal will now differentiate between the type of showers, electric or boiler fed and also the flow rates they are commissioned to. It is likely that the use of electric showers will have a negative impact upon the calculations when compared with gas boiler fed showers, due to the carbon emission factor discussed earlier. 

There is potential for SAP 2016 to be published in 2018, following the publication of the review of the Building Regulations that is currently being undertaken by Dame Judith Hackitt. Subject to the conclusions of that review, the Government intends to consult on adopting the technical changes to SAP, outlined in their consultation documents, as part of its consultation on making improvements to Building Regulations energy requirements in England, where they are cost effective, affordable and safe opportunities to do so.

The recommendations mark a step in the right direction – an acknowledgement that as technology and building methodologies change, regulations need to change with them. With regulations moving in step with technological and lifestyle changes we will ensure that we are designing and building housing stock that is fit for the future.  

If you require any help and support in complying with the regulations as they change, please get in touch with us and our expert assessors will be happy to assist you.

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