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On Construction EPC & SAP Compliance Services UK

Specialist energy consultancy for architects and developers. SAP calculations, EPC certification, and compliance support from design to completion.

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Energy Compliance Made Simple

We simplify Building Regulations compliance with clear, practical guidance from early design to final certification. Getting your Part L Building Regulations compliance in order from day one saves a lot of headaches later, whether you are working on one house or a 20-unit scheme. We work from your drawings at each stage, so there are no surprises when Building Control comes knocking.

What is an On Construction EPC?

Required for all new builds in the UK. Based on SAP calculations and issued at completion stage.

Mandatory for new builds

Based on SAP modelling

Issued at completion stage

People often confuse this with the standard EPC on an existing home. They are not the same thing. An On Construction EPC is produced from the design specification, your insulation values, heating system, glazing details, air permeability score, and thermal bridging data. No assessor needs to visit a finished property to produce it.

The rating scale runs A to G, and Building Control will not sign the project off until a valid certificate has been lodged with an accredited scheme. On top of that, the SAP calculation behind the EPC has to prove the property hits the Target Emission Rate, Target Primary Energy Rate and the Target Fabric Energy Efficiency level required under Part L. Miss any of these, and you have a compliance problem on your hands.

How It Works

1. Design Stage
SAP calculations from drawings

2. PEA
Predicted energy assessment

3. As Built
On-site verification stage

4. EPC Issued
Final certificate lodged

Each stage leads into the next, and skipping ahead causes problems. The design-stage SAP gives you the performance targets the build has to meet: U-values for walls, floors, and roof, the heating efficiency, and the air permeability figure.

That feeds into the Predicted Energy Assessment, which goes to Building Control before work starts on site. Once the build is finished, the as-built check confirms nothing has drifted from the design. Boiler swapped mid-build? Insulation spec changed? Those updates go into the calculation before the final certificate is lodged, and your As built certificate is issued.

Why EPCs Matter

Ensures UK Building Regulations compliance

Improves energy efficiency outcomes

Prevents costly redesigns later

There is a commercial side to this, too. Buyers are reading EPC ratings more carefully than they used to, and so are mortgage lenders. A new-build coming in at B or above is what the market expects now. If a rating comes back low and it is flagged late in the programme, fixing it usually means extra insulation, a different heating system, or both. Catching the problem at the design stage costs a fraction of catching it on site.

What is Building Energy Modelling?

Building energy modelling is how we calculate what a building’s energy performance will look like before it is built. For new homes in UK, the approved method is SAP, the Standard Assessment Procedure. It pulls together the fabric specification, the heating and hot water system, ventilation, and lighting into a single compliance figure.

For a standard new-build house, it is fairly straightforward. More complex projects, ones with solar panels, non-standard construction methods, or high glazing ratios, need the model set up carefully, or the results will not hold up at the as-built stage. We carry out the building energy modelling as part of every SAP assessment we do. Where there is a risk of a compliance gap, we flag it early and explain what needs to change, in plain terms, while there is still time to do something about it.

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FAQs (Frequently Asked Questions)

1. Is an On Construction EPC the same as a regular EPC?

No, a standard EPC is done by an assessor visiting an existing property. An On Construction EPC is different; it uses SAP calculations based on your drawings and spec, not a physical inspection. Every new-build residential property in the UK needs one under Part L of the Building Regulations before Building Control will sign the project off.

2. When is the right time to get a SAP calculation done?

As early as possible, ideally before the construction drawings are locked. A design-stage SAP shows whether the spec will pass Building Regulations while changes are still easy and cheap to make. Leaving it until the build is finished and then finding a compliance gap is a much bigger problem to sort out.

3. How quickly can you turn it around?

For design-stage calculations, three to five working days once we have complete drawings and a full spec. As-built assessments are done once the build is finished and completion certificates are in hand.

4. What do you need from me to get started?

Floor plans, sections, elevations, and construction specification as well as details details of the heating, hot water, and ventilation systems. If some of that is still being confirmed, send what you have, and we will work with it.

5. Is the building regulations compliance certificate the same as the EPC?

No, the compliance certificate comes from Building Control once they are satisfied the project meets all the relevant requirements, including Part L. The On Construction EPC is one of the documents you have to provide to get there. No EPC, no compliance certificate.