SAP Consultation Response Published

On Friday 17th November BEIS published the industry responses to the consultation on proposals to amend SAP, with the next version known as ‘SAP 10’. The full consultation response can be found here. Elmhurst have analysed the responses in detail and noted the following important points.

When will the next change in SAP occur?

The consultation response stated;

“We expect the SAP 10 methodology to be published in 2018, but it may be used by Government for modelling purposes before publication. This publication will not bring the changes to SAP into force. This will be subject to consultation on changes to the Building Regulations.

The Government has commissioned an independent review of Building Regulations and fire safety in England, being led by Dame Judith Hackitt. The review is due to report in spring 2018. Subject to the conclusions of that review, the Government intends to consult on adopting the technical changes to SAP outlined in this document as part of its consultation on making improvements to Building Regulations energy requirements in England where there are cost effective, affordable and safe opportunities to do so.

Adoption of these changes to SAP in Northern Ireland, Scotland and Wales is a devolved matter.”

Therefore, for England at least, it appears there is to be a consultation in 2018 in regards to the next amendment to Part L, this was also mentioned in the recent Clean Growth Strategy document issued by BEIS. If there is a change to Part L following this consultation it is expected that SAP 10 will be adopted in the next version of the regulations.

Who responded to the consultation?

BEIS confirmed there were 176 unique responses to the consultation. These responses were from the following groups;

Elmhurst submitted a detailed response which can be viewed here. Broadly speaking most of the amendments were supported, however some concerns were raised in regards to a lack of flexibility in supporting innovative building methods/technologies and making the methodology overly complex in certain areas.

What changes were originally proposed?

Nineteen different proposals were outlined in the original consultation, two of which were specifically aimed at RdSAP. There was also a request for data to support changing the SAP procedure without changing building regulations, however this now appears unlikely to happen.

Many of the proposals were changes to the SAP calculator that will be taken care of by approved software products. However the following would result in changes to current assessment practices of OCDEAs.


It was proposed to overhaul the lighting calculation following criticism from stakeholders that it did not differentiate between different types of low energy lights, and did not take account of poorly designed lighting systems. This would require input of light fitting type and performance rather than a percentage of how many fittings are low energy.

The majority of responses were in favour of this approach and the government have decided to implement this into SAP 10, but not into RdSAP as it was deemed too complicated for existing dwelling assessments.

Thermal Bridging

It was proposed to raise the default y-value from 0.15 to 0.2 to prevent assessors using the default where a calculated value results in a higher y-value.

It was also proposed to end the use of the Accredited Construction Details scheme. This was due to the age of the scheme and the accuracy of the psi values available in SAP currently for the scheme. Assessors would need to source psi values from alternate schemes or calculate bespoke psi values for junctions.

Again the majority of responses were in favour of these changes with some suggestions of different y-values for different building types and also for design stage and as built stage assessments. This will be reviewed again in future as the default y-value is part of approved document L1A so would require a regulatory change.

Treatment of Elements Next to Unheated Spaces

The consultation proposed changing some of the ‘shelter factors’ applied to u-values for elements adjacent to unheated spaces. It was also proposed to introduce a similar approach for psi values where junctions are next to unheated spaces.

The responses were generally in favour of the proposals, however some criticism of the complexity of applying shelter factors to psi values was received. As a result of this the changes to shelter factors for u-values will be adopted, but the application of shelter factors to psi values will be reviewed further and if it is deemed too onorous it will not be not be adopted in the next SAP version.


Hot Water Methodology

Some criticism of the hot water methodology was received in regards to not taking account of shower types and the electricity used by electric showers.

Again the responses received were strongly in favour of this change. This will require OCDEAs to enter flow rates for showers into SAP assessments which will be used to calculate the volume of hot water required. It was also decided that different cold water temperatures will be used for systems with header tanks and those taking cold water directly from the mains feed – again this will require the OCDEA to determine which approach is being used in the dwelling.

Solar PV Systems

The consultation proposed allowing data from MCS certificates to be directly input into SAP assessments due to the detailed shading calculations undertaken by the MCS scheme. It was also proposed to extend the overshading options in SAP for near and far field obstacles.

Responses were split on this, with 37 in favour and 33 against. There was support for entering MCS data, however many of the responses deemed the additional assessment of near and far field obstacles to complex. Therefore the government have decided to allow the use of MCS data, but not adopt the proposal for more detailed overshading assessment of arrays.


Elmhurst welcomes the proposed improvements to the calculations to keep them up to date and relevant. Here at Elmhurst we not only welcome the proposed changes, we are hugely supportive of the research and empirical data undertaken as they all contribute to a refinement of the methodology and as such will result in more accurate and relevant EPCs. We look forward to using the next version of SAP whenever it is introduced in the future.

It appears 2018 will be an important time for the future of Building Regulations, with the outcome of the independent review by Dame Judith Hackitt due in the spring. Elmhurst then expects a further consultation on the next version of building regulations to follow, and as always we will be campaigning for meaningful improvements in energy efficiency to be at the core of the next version of Approved Document L.

Article Published: 28th November 2017

If you need help get in touch!

Fill out our short contact form below if you would like to find out more about the information displayed on this page

© Elmhurst Energy Systems Ltd 2022. All rights reserved.
Elmhurst Energy Systems Limited is registered in England, Company Number: 02805846