The why, what and when of SAPs (Standard Assessment Procedures)

Thermographic image of wall

Many people are familiar with EPC’s (Energy Performance Certificates), which are a mandatory requirement for a property sold or rented. The work done in creating them starts even before a single brick is laid. The first step in creating an EPC for a new house starts with a SAP (Standard Assessment Procedure) calculation, which is initially carried out at the design stage of a project, before any work commences on site. But what are SAP’s and why do we produce them for new dwellings? What are they trying to achieve?

A SAP calculation is an indication of a dwelling’s performance, calculated using a government approved, standardised assessment methodology (the SAP) that as an output, gives an indication of carbon emissions and fuel costs associated with occupying a dwelling in a standardised, average way.

It’s not the results of you, I or the Jones’ family living in it, nor will the costs it outputs match what you or I would pay to run the dwelling; instead costs and emissions are based on the floor area and on standardised occupancy and heating patterns. This allows a purchaser or prospective tenant to compare two or more similar houses in terms of typical cost to run and carbon emissions asociated with operating it, with each based on the same standardised occupancy. In other words – it provides a ‘level playing field’ so that comparisons can be made between different dwellings.

The assessment also includes a checklist for compliance against the building standards and regulations guidance document requirements. This allows Building Control to check that a dwelling complies with whichever building standards are dictated for the dwelling’s location.

The point behind SAP assessments is to try and achieve:

  1. A reduction in energy consumption (and greenhouse gas emissions) for new buildings through better levels of performance.
  2. Compliance with European and National regulations and standards.

What is measured?

SAP determines, in accordance with the European Performance of Buildings Directive (EPBD), the ‘energy performance of a building’, which includes within it the amount of energy actually consumed or estimated to meet the different needs associated with a standardised use of the building This includes space heating, hot water heating, cooling, ventilation and lighting. It excludes non-regulated energy use, such as for cooking or appliances.

The cost  and associated carbon equivalent emissions for different fuels for the calculated energy demand is determined by the software and this forms the basis of the energy efficiency rating (SAP rating) and of the Environmental Impact (CO2 rating).

The calculation considers the dwelling’s insulation, technical and installation characteristics, design and positioning in relation to climatic aspects, solar exposure and influence of neighbouring structures, own-energy generation and other factors, including indoor climate, all of which influences the energy demand.

So what’s involved / what do Building Control want to receive?

Approved Document L1A (2013) for England and L1A (2014) for Wales and Scottish Building Standards Section 6 (2011) all give guidance as to how to reasonably demonstrate to Building Standards/Building Control that a building has been constructed in compliance with the appropriate energy efficiency requirements.

This is done through a Design stage energy assessment submission before work starts and then an As Built submission on completion, with both submissions showing that the dwelling will meet, or has met required targets (along with specifically how this is, or has been achieved).

The two submissions are used by Building Standards/Building Control to check compliance of the design and of what is actually built.  A clear connection must be evident between product specifications and the data inputs into the compliance software used (following the SAP calculation procedure and conventions).  The calculations for the As Built submission are used to produce the Energy Performance Certificate for the completed dwelling.

The two submissions are a mix of mandatory requirements, which must be achieved and statutory guidance, which if followed, demonstrates reasonable provision that the criterion from the regulations have been met.

In my next post I’ll take you through a typical project and calculation, outlining what an assessor would look for and what goes into a calculation.

SAP calculations can be carried out by Kingspan Insulation for your project using our accredited energy assessors. More details are available on the SAP pages of our website.

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Jon Ducker is a qualified energy assessor working for Kingspan Insulation Ltd. He has an extensive knowledge of energy efficiency, renewable energy systems and sustainability in buildings with an expert knowledge of the relevant sections of buildings regulations and standards and their interactions with SAP. He provides authoritative advice regarding energy assessments for a wide range of public and private sector clients.

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