Energy statement for a single self-build dwelling
A single dwelling energy statement should be four to six pages answering one policy clause by clause. Most are either missing or four times too long.
For a single self-build dwelling, an energy statement is usually four to six pages and it answers one question: how the house will meet the energy and carbon requirements in the adopted local plan policy that applies to it. Most applicants either skip it, and get a validation query, or produce a 40 page document full of modelled outputs the case officer cannot use.
Start by checking whether you need one at all. Many authorities require an energy or sustainability statement for all new dwellings through their local validation list, and many do not require one below a unit threshold. The local list decides it, not the national requirements.
When a single dwelling needs one
Three triggers, in order of how often they apply. A local plan policy requiring a percentage carbon reduction or a renewable energy contribution for all new dwellings. A local validation list item requiring an energy or sustainability statement for any new build. Or a constraint-driven requirement, such as a policy in a design code or an area action plan.
If none applies, a short paragraph in the planning statement covering the fabric approach and the heating strategy is normally enough, rather than a full Energy Statement. Do not volunteer a full statement where none is required. It creates commitments you then have to satisfy at discharge of conditions stage.
Where a statement is required, read the policy wording first and write the document to answer it clause by clause. A policy asking for a 20 per cent reduction against the building regulations target is answered with a number, not with a description of your insulation.
What the council actually reads
The case officer is not an energy assessor. They read the first page, the compliance table and the conclusion, and they pass the rest to a sustainability officer only if the authority has one.
So put a single table near the front showing the policy requirement, the figure achieved, and where the evidence sits. Then write two pages of explanation behind it. Everything else belongs in an appendix.
| What the policy asks | What to state | Evidence |
|---|---|---|
| Percentage improvement on the regulations target | The figure achieved | Design stage SAP output |
| Renewable or low carbon contribution | Technology, capacity, predicted annual output | Manufacturer data and the SAP output |
| Fabric standard | U-values by element, airtightness, thermal bridging approach | Specification schedule |
| Overheating | The route to compliance and the result | Overheating assessment |
| Water efficiency | Litres per person per day target | Fittings schedule |
That table, filled in honestly, is most of the document.
Fabric specification and the modelling behind it
Design stage SAP is a building regulations calculation, and planning borrows its outputs. That distinction matters because a planning condition requiring a percentage improvement is discharged against an as-built calculation, not the design stage one, and the gap between the two is where self-builders come unstuck.
Give U-values by element rather than a general claim about a fabric-first approach. Walls, roof, floor, windows and doors, with the airtightness target and the approach to thermal bridging, because psi values at junctions make a material difference to the result and a default assumption costs several percentage points.
Two honest notes worth including. Airtightness is achieved on site rather than on paper, so say who will be responsible for it and when the test will happen. And a highly insulated, airtight house needs mechanical ventilation with heat recovery designed properly, which is a commissioning issue as much as a specification one.
Heating and hot water
The strategy question for a new self-build is now usually whether to connect to gas at all. An all-electric house with a heat pump avoids the connection cost, aligns with the direction of national policy, and produces a better result in the carbon calculation as the grid decarbonises. The counterweight is a higher capital cost for the system and the cylinder space it needs. The gas connection decision turns on the specifics of the site rather than on a general rule.
If you choose a heat pump, say which type, the seasonal efficiency assumed, the emitter strategy at the flow temperature assumed, and the hot water cylinder volume. Those four numbers are what a reviewer checks, because a heat pump modelled at a flow temperature the radiators cannot deliver produces a compliant calculation and a cold house.
Direct electric heating with a very high fabric standard can also comply, and on a small dwelling it sometimes wins on capital cost. Say so if that is the route, rather than dressing it up.
On-site renewables at one-house scale
Photovoltaics are the default, because the calculation credits them, the roof is already there and the maintenance burden is low. State the array capacity, the orientation and pitch, the shading assumption and the predicted annual generation.
Battery storage improves self-consumption and the household bills but usually does nothing for the planning calculation, so include it as a statement of intent rather than as part of the compliance case. Solar thermal is now rare on new build because the photovoltaic and heat pump combination does the same job more simply. Wind at single dwelling scale almost never justifies itself outside exposed rural sites.
Where the policy asks for a percentage of energy from renewables rather than a carbon reduction, check carefully which denominator the policy uses, because regulated energy and total energy give very different answers and policies are often silent.
Cost implications, honestly
Nobody can give you a reliable figure for these choices without a specification and current quotes, and anyone who does is guessing. What is reasonably stable is the ranking: fabric improvements are the least costly route to the first increment of carbon saving, photovoltaics the least costly route to the next, and heat pumps carry the largest capital step but change the operating position.
Get three quotes against a written specification rather than against a performance target. On a one-off house the difference between quotes for the same specification is routinely larger than the difference between specifications.
Conditions likely to be attached
- Development to be carried out in accordance with the approved energy statement, with as-built evidence before occupation.
- Details of the renewable energy installation to be approved before the relevant part of the works.
- Water efficiency at the optional higher standard of litres per person per day, where the local plan applies it.
- Electric vehicle charging provision.
- Overheating mitigation in accordance with an approved assessment.
Condition one is the one that bites. Read it before you accept the permission, because it commits you to the figures in your own document, and a document that over-promised is expensive to discharge. An Overheating Risk Assessment is often needed alongside, particularly for a house with large south or west glazing, and the two documents should share the same fabric and ventilation assumptions.
Where the plan requires broader sustainability measures beyond energy, a Sustainability Statement covers materials, water, waste and biodiversity, and it should not repeat the energy statement.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
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Frequently asked questions
Does a single new house need an energy statement?
Only where a local plan policy or the authority's local validation list requires one. Many authorities require an energy or sustainability statement for all new dwellings, and many set a unit threshold. Check the local list rather than the national requirements, and where none applies, cover the approach in a paragraph of the planning statement instead.
What should be on the first page?
A table setting out each requirement in the applicable policy, the figure achieved against it, and where the evidence sits. The case officer is not an energy assessor and will read the front page, the compliance table and the conclusion. Everything technical belongs behind that, and modelled outputs belong in an appendix.
Is a SAP calculation a planning document?
It is a building regulations calculation that planning borrows from. A design stage output supports the application, but a condition requiring a percentage improvement is discharged against the as-built calculation. The gap between design stage assumptions and as-built performance, particularly on airtightness and thermal bridging, is where self-builders get caught.
Should the house be all-electric?
Often, though it depends on the site. An all-electric house with a heat pump avoids the gas connection cost, matches the direction of national policy and improves as the grid decarbonises, against a higher capital cost and the space a cylinder needs. State the heat pump type, seasonal efficiency, flow temperature and cylinder volume if you go that way.
Do batteries help the planning case?
Rarely. Battery storage improves self-consumption and household bills but generally does not change the compliance calculation, so present it as a statement of intent rather than as part of the policy case. Photovoltaics are the technology the calculation credits, so state array capacity, orientation, pitch, shading assumption and predicted annual generation.
What conditions usually follow?
Development in accordance with the approved energy statement with as-built evidence before occupation, details of the renewable installation, water efficiency at the optional higher standard where the plan applies it, electric vehicle charging, and overheating mitigation. The first of those commits you to your own figures, so read it before accepting the permission.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.