What are SAP Calculations?
The SAP Calculation process was developed by the Department of the Environment back in the mid-90s as a means of measuring energy usage. The SAP Calculation is required under Part L of the building regulations.
SAP Calculations are a fundamental part of the planning and building process, but we know that they can appear complicated and confusing, especially if you’re new to the process.Take a look at our quick guide to the basics – this is something you need to understand as your developing your build project.
What is SAP?
The Standard Assessment Procedure is a governmental system which assesses the energy rating of new build, conversions, renovations and extensions.
The SAP assessment process has to be carried out by accredited SAP assessors.
A SAP Rating works on a like-for-like comparison of build performance. The assessment will give your build a rating between 1 and 100. If you achieve a high SAP Rating your fuel costs will be low and so will your Co2 emissions.
The SAP Calculations energy cost is based on the following:
- The building construction
- The heating system installed
- Internal lighting fixtures and fittings
- Any renewable energies installed
The SAP calculation does not measure energy used for domestic appliances, or cooking.
Why is SAP important to me?
Without SAP your build will not be compliant with current building regulations, which means that it can’t be signed off by building control, which means that it can’t be sold or let.
The SAP rating you receive provides prospective buyers or tenants with key information regarding the energy performance of the build; this comes in the form of the Energy Performance Certificate (EPC) which is generated as a result of the SAP Assessment
SAP is of fundamental importance to your build project.
SAP may just sound like one more piece of red tape to negotiate, but there’s more to it than that. The SAP assessment is designed to help you to plan the most efficient energy profile for your new build. Working with a skilled SAP assessor helps the project’s architect or designer to minimise energy use and guarantee low carbon emissions.
How is energy performance measured by SAP?
In order to achieve a ‘Pass’ rating, the following elements are assessed:
- The loss of heat through the fabric of the build
- Solar gain
- The construction quality and commissioning of systems
- Calculations based on predicted Co2 emissions from the dwelling
The Importance of Co2 emissions
Your Co2 emission rating is calculated on a like-for like comparison assessment. It’s a key driver arising out of the process because the Co2 emissions target is now used by local councils and planners as a determinant of 106-type community contributions.
You may have seen reference to DER/TER figures; these represent the headline emissions targets and they are calculated by comparing a Target Emission Rate (TER) against the predicted Dwelling Emission Rate (DER).
How is the SAP Assessment Arrived at?
An accredited SAP Assessor will work from the architect or designer’s plans and construction detail, as well as the heating, ventilation and air-conditioning (HVAC) specification. IN order to achieve an accurate assessment the drawings provided will need to be professionally produced, showing elevations, sections, site and floor plans.
A model of the build will be created by the SAP Assessor, either by hand or using SAP software.
The model forms the basis of the Site Form. Once this is completed heating, lighting and ventilation systems are included. These will be identified using manufacturer’s databases wherever possible.
Walls, floors, roofs and openings (the thermal elements) are included at this stage, together with any renewable energies and cooling systems included in the build plan.
Once all the elements of the build have been collated by the SAP Assessor, the SAP Calculation will produce the following outputs:
- Heat loss
- Seasonal variation of energy demand
- Co2 emissions
- Renewables contributions
How Can I Guarantee a SAP Calculation Pass?
Significant changes were made to the SAP regulations in 2009, which has meant that build developers and architects are now experiencing a set of extremely rigorous building regulations.
The primary driver of these regulations is the Co2 emission target, which have tightened significantly due to UK and European Climate Policy. It’s safe to say that builds which achieved a SAP Pass pre-2009 would be unlikely to do so today.
It’s important to emphasise that there isn’t a formula for achieving a Pass; the SAP Assessment is now far from being a tick-box compliance exercise. Failing the SAP Assessment could come down to many different factors; it could be to do with the thickness of floor insulation, boiler size, even the way the house is pointing!
Not all factors which feed in to the SP Assessment are within the control of our clients. We have experienced situations where the lack of a connection to mains gas has meant that other fuels – with a higher cost and Co2 emission – have to be used instead. Sometimes environmental factors force you into decisions that can create problems with your SAP Assessment. When this happens, we take a deep breath and work with what we have.
Any Advice?
Plenty! At Hilsdon Holmes we work with the SAPs Assessment every day, on a whole range of different types of builds, so we have a clear understanding of the process and we base our advice on our daily experience from self-builds to extensive conversions.
We never try to achieve a zero-carbon house; rather we try to achieve the very best results for our clients based on the realities of the situation and context of their project.
Here are our guiding principles:
- Insulate the fabric of your building effectively and you won’t need to worry about renewable technologies to get your SAP Pass. Our rule of thumb is: design for maximum insulation when it comes to floors, walls and roofs – then add some more.
- Be ultra-aware that you doors and windows will represent high heat loss areas. Try to get the u values as low as possible on all your build openings.
- Pay attention to your boiler controls. Load and weather compensators, as well as zoned heating controls will have a significant effect on your SAP Rating.
- Your build will require an Air Permeability Test, and the results will feed in to your SAP Assessment. Make sure that your build envelope id efficiently and effectively sealed, and get a pre-test booked before you go for the real thing.
- Be aware that heat loss through junctions with external walls – or thermal bridging – can cause problems for the SAP Assessment. We would advise that you use a scheme like ACD (Accredited Construction Details); this gives us the opportunity to avoid default figures when assessing your build.
Don’t delay – Getting started early on your SAP Assessment is key to success!
We need to receive plans at the start of your build project if we are to provide effective advice on changing the energy performance of the building.
If we receive plans halfway through the process, there’s not much we can to improve the energy performance. We’ve seen quite a bit of unprofessional practice arising out of situations like this; where bad advice is given just to get the build through the planning regs. And it usually costs a fortune along the way.
Appoint a SAP Assessor early and open the lines of communication with them as soon as possible. What do we mean by early? Normally we would advise before planning has been submitted, well before your building regs applications.
Is SAP Just for New Builds?
No. If you are planning an extension, conversion or change-of-use scheme you many very well require a SAP Assessment under Part L1b of the building regs:
- Extensions with more than 25% glazing-to-floor area (SAP Calculations for Extensions)
- Barn conversions
- Commercial to domestic conversions
- Conversion of a single dwelling into flats or apartments
