Wales writes its own Approved Document L, and it no longer matches England's. We model new dwellings, conversions and glazed extensions against the Welsh document — design stage through to the on-construction EPC — working remotely from your drawings, so a site in Gwynedd is handled no differently from one in Newport.
Devolved standards
Building regulations were devolved to the Welsh Government, and since then Wales has published its own Approved Document L rather than adopting the English text. Part L is still the part of the regulations that deals with conservation of fuel and power, but the guidance behind it — the notional dwelling, the compliance targets, the detailed provisions — has diverged. Two versions of the same nominal requirement now sit side by side.
The practical consequence is blunt: a calculation run against the English document does not demonstrate compliance in Wales, and a report prepared against the wrong guidance has to be redone. Editions are revised periodically too, so it is worth confirming with your building control body which one applies to your application date.
Who checks it: building control in Wales runs through local authorities — Cardiff, Swansea, Newport, Wrexham, Gwynedd, Powys, Pembrokeshire and the rest — or through a private approved inspector. Either route expects the design-stage SAP with the application, and the as-built assessment before completion is signed off.
Getting started
Everything below arrives by email. There is no appointment to book and no site visit at design stage — the model is built from the documents, which is why the service suits a smallholding conversion in Ceredigion as readily as a city-centre apartment block.
| What to send | Why it is needed |
|---|---|
| Scaled floor plans | Floor areas, room layout and the heated envelope |
| Elevations | Window and door sizes, orientation and overshading |
| Sections | Storey heights, roof form and the volume being heated |
| Construction build-ups | Wall, roof and floor make-up so U-values can be established |
| Glazing specification | U-values, g-values and frame type for windows and doors |
| Heating & hot water | Appliance make and model, controls, cylinder and any secondary heating |
| Ventilation strategy | Extract, continuous mechanical or heat recovery, with the unit specified |
| Renewables | Photovoltaic array size and orientation, heat pumps, waste water heat recovery |
Not everything settled yet? That is normal at design stage. Send what exists and we will model sensible assumptions, then flag which of them the finished building actually has to live up to — including the air-tightness figure your builder needs to know about long before the test fans arrive.
Welsh projects
Much of Wales is smallholdings, former farm buildings and one-off plots rather than volume housing sites. Barn and outbuilding conversions are a material change of use, which brings energy requirements with them, and they rarely resemble a standard house type — irregular geometry, thick masonry, awkward thermal bridging. Those are modelling problems, solved from the drawings, not from standing in the yard.
Welsh housing stock includes a great many solid-wall stone properties, where an internal or external insulation upgrade cannot simply be looked up in a table. The build-up has to be calculated for the specific construction proposed, and the result feeds both the compliance case and the decision about how much insulation is worth fitting. Our U-value calculations cover exactly this, alongside the SAP work.
Elmhurst Energy accredited. Every assessment is produced under accreditation and audited to that standard, whether the project is a single dwelling in Pembrokeshire or a phased development in Wrexham. See the full range on the main SAP calculations page, or send your drawings for a fixed quote.
Common questions
It depends on the size and complexity of the scheme — floor area, how many distinct dwelling types there are, and how complete the drawings are. Send the drawings through the quote form for a fixed quote. The work is produced remotely, so a plot in rural Powys is quoted on the same basis as one in Cardiff.
No. Building regulations are devolved to the Welsh Government, which publishes its own Approved Document L for Wales. It has diverged from the English version since devolution, so targets, the notional dwelling and detailed provisions differ between the two. An assessment must be run against the Welsh document, and it is worth confirming with building control which edition applies to your application date.
Not for a design-stage SAP. The model is built entirely from drawings, build-ups and the heating and ventilation specification, so the assessment is produced from what you email us. No travel means location has no bearing on turnaround, and the work is carried out to the same accredited standard wherever the site is. At completion we need the air-pressure test result and any on-site changes.
Often, yes. Creating a dwelling from a building that was not previously one — a barn, a chapel, offices above a shop — is a material change of use and usually needs a conversion SAP. An extension can also need one where the glazed area is large relative to its floor area, because compliance is then shown by calculation rather than by meeting standard element limits.
Yes. The on-construction EPC for a new dwelling is generated from the finished as-built SAP rather than from a separate survey, and it is lodged once the assessment is complete. That is the certificate building control, the buyer's solicitor and any lender will look for.
Tell us the property type and postcode — we'll come back with a fixed quote and the earliest available date.