Calculations for Extensions and New Build Projects
SAP Calculations-made simple
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SAP Calculations & EPCs
Important information for SAP calculations- post June 15th, 2022
Since June 15th, 2022 the UK Building Regulations have been updated, favouring properties with electricity as their primary energy source (this is due to the increase in use of renewable technology to produce electricity over the last decade). How can your project achieve compliance? We will work closely with you or your architects team on solutions that will lead your project to comply with Part L. We can also provide calculations and a report to demonstrate compliance with the new Part O of the Building Regulations, as well as help your project comply with the London Plan, which interestingly thorough the beginning of 2023 we are also starting to see adopted by other councils around the UK (please read my blogpost if you are interested in seeing how this follows similar patterns in the past). Please call me, or fill in my online form with your projects details if you simply want some guidance and chat about your options.
SAP Calculations '101' and tips to get a better result on your project
SAP (which stands for Standard Assessment Procedure) Calculations are required on most New Build Properties and some Extensions due to Part L of the Building Regulations (you can read more about Part L in detail through the link). In short, its a requirement by the government that all New Build Dwellings in the UK have a SAP calculation. That's interesting, as in some circumstances it also means a SAP Calculation is required for an extension to an existing Buildings or even in a Building Conversion project. The building works cannot (or should not!) start without these calculations.
What is a SAP Calculation aiming to achieve?
The basic idea is that the UK is trying to get all new buildings to be as energy efficient as possible and thus reduce the carbon footprint we are producing. For this reason, on 15th June, 2022 SAP Calculations underwent a major over hall to SAP 10. This has significantly affected the SAP Calculations for new builds, extensions and conversions. Please click here for a detailed break down of SAP 10 if you were familiar with SAP Calculations previous to this date but aren't sure of what's changed..
There are basically three stages of SAP Calculations required for any new build project, whether New build, Extensions or conversions:
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'As Designed' SAP Calculations
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'As Built' SAP Calculations
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'EPC' (Energy Performance Certificate)- Produced from the As Built SAP Calculations
As the SAP Calculations are taken from the buildings plans and specifications, at present there is generally no need for me to visit the property as most, if not all, of the required information can be gathered from remotely.. In this webpage I will explain in detail what are each of these SAP Calculations are and also what is required for SAP Calculations for extensions and SAP Calculations for conversions.
Design Stage SAP Calculations explained
To be able to produce SAP Calculations you (or your representative, architect, builder etc.) will need to supply us with the following information:
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Detailed Scaled Plans with North Orientation
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Scaled Elevation Drawings
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Planned Heating,, air-con and ventialtion (HVAC) Specifications
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Planned Water Heating Speciifcations
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Planned Lighting Specifications
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Any renewable technology you plan to fit
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Detailed Specification of the Building Fabric, (ideally with planned building products works best)
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Details for planned windows and doors, skylights etc.. and thermal bridging
I compile this detailed information and enter the calculations into an approved government software (SAP) to see if the planned building or extension complies with Part L of the Building Regulations. These are important calculations as the actual building will be measured against them, and any deviation from these (Intentional or unintentional!) may lead to the actual building or extension not passing and expensive remedial works needed in order for the building to comply! Thankfully though, you will be please to know that would be impossible if the plans and specifications are implemented correctly. Another reason to make sure you have a reliable builder and project manager for your project!
Occasionally, the submitted plans don’t meet Part L for various reasons and that's when I will work with you or your architects to quickly find solutions that work but are also practical and cost effective.
If I am also instructed to carry out the ‘As Built’ SAP Calculations, during the build, with you permission I like to keep close contact with the project manager or architect and am happy to recalculate any potential changes to the project along the way to ensure all is smooth and we still comply when we get to the ‘As Built’ Stage.
All you need to know about ‘As Built’ Stage SAP Calculations
Once the project has been completed, we will need to prove that everything we calculated at the ‘AS Design’ SAP Calculations stage has been installed and the beautiful new finished building still complies. If everything has been built to plan, that is relatively straight forward however it can be more challenging if there have been changes that I don’t know about so, please, keep me informed through the project of any changes! Remember I am here to support you and want the project to comply as much as you do. Once we have achieved compliance I will send you an ‘As Built Sign Off’ Document which you or your representative will sign to confirm the project is built to the discussed details (Including any changes we made on the way!) and complies with Part L of the Building Regs.
At this stage I will also need other supporting documents to produce the ‘As Built’ SAP calculations such as:
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The air tightness certificate
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Thermal Bridging Junctions Checklists or Illustrations
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Microgeneration Certificate Scheme (MCS) Certificates ( If applicable)
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Heating/ Ventilation commissioning Certificates.
Energy Performance Certificate (EPC) Report
This Certificate contains the multi-coloured energy graph many are now familiar with and information about the property presented in an ‘easy to read’ format. The SAP Energy Performance Certificate (EPC) is different to the RdSAP EPC used in existing buildings and can only be produced using the details provided in the ‘As Built’ information by an ‘On Construction Domestic Energy Assessor’ (OCDEA). It is easier for me to produce the EPC if I have calculated the building at the previous stages, however I am qualified and experienced in existing and new building assessment so can advise you correctly if there is any uncertainty which type of EPC is required. In certain circumstances I can produce an EPC on a new build property without having been involved in earlier stages of the project.
In September 2020, the government launched a new Energy Performance for Buildings Register for England, Wales and Northern Ireland (Note not Scotland- It is a different register). The EPC will be stored and accessed from here and is valid for 10 years, regardless of how many times the property is sold or rented.
SAP Calculations for Extensions made simple
So you have applied for an extension to your house with lots of shiny, bright glazing, perhaps even with large bi-folding doors. You submit your application and Building Control have asked you for a SAP calculation for your extension before you can proceed. Why? Part L of the Building Regulations stipulate that the glazed area of your extension must be less than 25% of the extensions floor area. Any greater amount than that (eg bi-fold doors on a smallish kitchen extension) will generally mean SAP Calculations are needed to prove compliance with part L.
How does it work in practice?
SAP Compliance for new extensions can essentially be split into main two areas:
1/Limiting the areas of openings
2/ensuring robust fabric standards.
What does that mean? Here is the actual wording from Part L of the Building Regulations:
“ In most circumstances reasonable provision would be to limit the total areas of the windows, roof windows and doors so that it does not exceed the sum of;
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25% of the floor area of the extension
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The total area of windows or doors which as a result of the extension no longer exist or area exposed."
Most modern extensions have a preference for more than 25% glazing ( your nice bi-folding doors!) which exceeds the limits set in paragraph 4.2 of AD 1LB. The SAP Assessment demonstrates compliance by offsetting against the original building despite these larger areas of glazing. Using the plans you will submit to planning I am usually able to demonstrate the extension will comply with the building regulations despite the larger amount of glazing present, and, if not compliant, I will help you find a cost effective way to ensure the project complies.
3 tips to help your extension achieve Building control compliance
Focus on the following areas:
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Thermal elements-look for cost effective ways to improve insulation to the extensions fabric- i.e. loft, floor walls etc
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Can you upgrade the thermal properties of the glazing? Often there is only a small cost difference to upgrade from double to triple glazing for example when ordering new windows.
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In the existing part of the building, could you make fabric improvements? Better insulation for example in the loft? We can use this to compensate for the extension and achieve compliance.
I would love to be involved in your next project. Why not fill in the online form or call me for a chat on 07800 654321 to see how I could help your project successfully meet the standards. I am between the UK and Spain but my mobile number is UK rates.
