Energy statements for minor residential schemes

An energy statement for a small development is a planning document, not a Building Regulations submission, and the difference explains most of the confusion. No national rule says a scheme of one to nine homes needs one. Whether you need an energy statement for one house depends entirely on the adopted local plan and the authority's validation list, and the two do not always agree.

Check both before you draw anything. A policy that applies to "all new residential development" means the single plot as much as the 200-unit scheme, and the validation officer will apply it to the letter.

When a minor scheme is asked for one

Three things bring an energy statement onto a minor application. A local plan policy requiring one for all new dwellings. A validation list item that names the document. Or a condition on an outline permission requiring energy details at reserved matters.

Read the policy wording rather than the policy title. Some ask for a percentage improvement in carbon emissions over the Building Regulations baseline. Some ask for a proportion of demand met by low carbon or renewable generation. Some ask only for a narrative explaining how the design reduces energy demand. Those are three different documents, and submitting the wrong one guarantees a further information request.

Where the plan predates the 2021 Building Regulations uplift, the target may be expressed against a baseline that no longer exists. That is a real problem and it is dealt with below.

What the policy is measuring

Since the 2021 edition of Approved Document L, a new dwelling is assessed against three targets generated from a notional building of the same size and shape: a Target Emission Rate for carbon, a Target Primary Energy Rate, and a Target Fabric Energy Efficiency rate. The 2021 uplift set the notional specification to deliver around a 31 per cent reduction in carbon emissions for new dwellings compared with the 2013 standard.

Your SAP calculation produces the matching Dwelling Emission Rate, Dwelling Primary Energy Rate and Dwelling Fabric Energy Efficiency figure. The Energy Statement reports those three against the targets and explains the design decisions that produced them.

Primary energy is the metric people forget. A scheme can pass on carbon and fail on primary energy, particularly where direct electric heating is proposed, and an officer working from a policy written around carbon alone will not spot it until Building Control does.

Fabric before technology

Officers and Building Control both prefer a scheme that reduces demand before it generates energy, and the local plan policies that follow the London approach put it in that order explicitly.

For a minor scheme the practical sequence is:

1. Improve the fabric U-values beyond the notional specification where the form allows, especially on a compact plot with a poor surface-to-volume ratio.
2. Reduce thermal bridging by using calculated psi values rather than the default figures, which are deliberately punitive.
3. Set a realistic air permeability target and specify the ventilation strategy that goes with it, because a tight house without mechanical ventilation with heat recovery is a comfort problem.
4. Choose the heating system.
5. Add generation.

The order matters commercially. Fabric decisions are locked in at foundation and frame stage. A solar array can be added in the final month, and it is the item most often value-engineered out after permission.

Heat pumps and how SAP treats them

The carbon factor for grid electricity used in SAP 10 is far lower than the figure in the 2012 version, which changed the arithmetic completely. An air source heat pump now scores strongly on carbon and reasonably on primary energy, and it is the straightforward route to meeting a percentage improvement target on a small site.

Two cautions from experience. The system needs a genuine low-flow-temperature emitter design, and a SAP model assuming 45°C flow with radiators sized for 70°C will not perform as modelled. And hot water matters more than heating in a well-insulated small house, so the cylinder size, the standing loss and any secondary circulation deserve attention before the array on the roof.

Where the plan asks for a proportion of demand from renewables specifically, check whether the authority counts a heat pump as renewable generation. Some do, some treat it as a low carbon technology and expect photovoltaics as well.

Overheating, and the report that goes with it

A well-insulated, airtight small house with large glazed openings on a south or west elevation will overheat. Approved Document O applies to new residential buildings and sets a simplified method and a dynamic modelling route.

Planning and Building Regulations diverge here in an unhelpful way. A planning officer can approve a design with a fully glazed gable that then fails the Part O simplified method, and the fix at that stage is smaller windows or external shading, both of which change the elevations you have permission for. Run an Overheating Risk Assessment alongside the energy work rather than after it, and put the shading and opening strategy on the submitted elevations.

Evidence the officer will look for

A usable energy statement on a minor scheme runs to a handful of pages and contains:

• the policy or condition being answered, quoted, with the target stated as a number
• the SAP output summary for each dwelling type, with the software version stated
• the notional and as-designed specification side by side, covering U-values, air permeability, thermal bridging approach and ventilation
• the heating and hot water strategy with the assumed flow temperature
• any generation, with the assumed array size, orientation and pitch
• the resulting percentage improvement, with the baseline named
• a short statement on overheating and how it is addressed

Where the policy target is expressed against an older Building Regulations edition, restate it. Say which edition the policy assumed, what the current baseline is, and what your scheme achieves against both. Officers accept that reasoning when it is set out plainly and resist it when it looks like an attempt to move the goalposts.

A Sustainability Statement covers the wider policy points such as water use, materials and waste, and on small schemes the two documents are often combined. Larger projects may also need a Whole Life Carbon Assessment, though that is rare below major thresholds outside London.

Conditions that follow approval

The usual condition requires the approved energy measures to be installed and retained, with evidence submitted before occupation. That evidence is normally the as-built SAP and the Energy Performance Certificate.

The trap is the gap between design SAP and as-built SAP. Substituting a different heat pump, dropping the array from 4 kWp to 2.5 kWp, or accepting a worse air test result all reduce the as-built figure, and the condition is written against the approved statement rather than against Building Regulations compliance. Discharge becomes a negotiation you did not budget for.

Keep the design SAP, the specification and the contract in step. Where a substitution is unavoidable, agree it with the authority before it happens.

PlanScope drafts an energy statement from your project details and the policy position, and flags the figures it cannot verify rather than inventing them. See PlanScope pricing for the free report, the single report price and the Professional tier for architects and agents.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.