SAP – Standard Assessment Procedure

The UK has a standardized way of measuring energy efficiency in buildings and this is known as the standard assessment Procedure (SAP). It is used to calculate how energy efficient homes and building are and could be using renewable technologies. Every few years, the government researches available energy technology and comes out with an “Assessment Procedure for Energy Rating of Dwellings.”

This is the basis for our Energy Assessment to see which energy saving measures and energy generating technologies will be most effective for you.

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The Basics

Most people will have seen the EPC – Energy Performance Certificates that is required every time a house is bought or sold – this is generated using the SAP calculations. These calculations provide information about the current energy performance of the home and what could be done to potentially improve this performance to both, save money and reduce carbon emissions.

We have taken these calculations and made some simple assumptions about some of the figures that would normally be entered into them. This means that, without loosing too much accuracy in the results, we have been able to create an assessment that you can complete online in a couple of minutes, quite literally.

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Reduced SAP

This the rating that is applied to all residential property which are already built, in other words all existing properties in the UK rather than newly built. Energy assessment for existing dwellings follows a method known as Rd SAP (Reduced data Standard Assessment Procedure).

This method is used as it is simpler and easily applied when performing energy assessments of existing residential property and sometimes it would be impossible to apply the full SAP rating.

Generally, older homes are less energy efficient than newer homes, over the years building standards and regulations have improved. Detached homes also have higher heat losses, as all external walls are deemed as heat loss walls, a terraced home for example will have less heat loss walls, and hence would have a better SAP rating for space heating in this instance

Energy Performance Tip

Home owners can gain up to 15 SAP points by having a condensing gas boiler installed! This improvement alone could put your home in a band above the current energy band if you have a conventional gas boiler installed.

See what you can do to improve your rating!


Will the new version of SAP produce the same results as the previous?
Because of changes to SAP, such as moving to a monthly based energy calculation and reduced water heating demand, and the assumptions used in relation to Part L of the Building Regulations there may be very small differences in the results compared with those produced using SAP 2005.
Why are we using the 2005 SAP methodology to assess CO2 emission factors?
It has been decided to continue using the SAP 2005 methodology for producing carbon emission factors based on the most up-to-date information available. Nonetheless, it was recognised that further work was required to examine the difference in carbon savings between distributed generation and grid based generation in terms of transmission losses. This will be considered, amongst other issues, as part of a proposed extensive review of SAP.
Is SAP meant to be a design or compliance tool?
SAP is a compliance tool. However, there is no reason why designers could not use it to predict the performance of different dwelling designs. Given that the assessment methodology and calculation principles are fully set out in the SAP document then software suppliers could easily make a design version available.
Why does DECC need to carry out further reviews of SAP?
It is necessary to periodically review SAP to keep it up dated and fit for purpose. In support of this aim DECC may consider issuing an interim revision of the SAP document, if this was necessary. Such a revision would enable minor changes to be brought into SAP before the next formal revision. It could possibly take account of information from work in progress, for example, field trials assessing the performance of products under installed conditions. Though, Appendix Q remains the principal route for introducing new product performance information in advance of a full revision to SAP. Interim revision would have no material impact on assessments previously carried out under SAP 2009.
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