Energy statement for a listed building with limited fabric change

A listed building energy statement has to make an argument that a new build statement never does: that the scheme delivers what it reasonably can, and that the shortfall against policy targets is justified by the duty to preserve the building. Sections 16 and 66 of the Planning (Listed Buildings and Conservation Areas) Act 1990 sit above the energy policy, and where a fabric measure would harm special interest, it is the measure that gives way. The statement's job is to show the work of getting there, measure by measure.

Start by separating the two consent regimes. Building Regulations and planning policy ask different questions, and the easements are not the same.

Where the energy hierarchy meets listed building consent

Approved Document L recognises that listed buildings, buildings in conservation areas and scheduled monuments need special consideration where compliance would unacceptably alter their character or appearance. Regulation 25B on nearly zero-energy buildings does not apply to protected buildings on the same basis.

That is a Building Regulations position. It does not automatically carry across to a local plan policy requiring a percentage carbon reduction, and it does not answer a London borough applying Policy SI 2 of the London Plan 2021 with the Greater London Authority's energy assessment guidance. Policy targets and their baselines have moved with the 2021 Part L uplift, so take the current figure from the adopted policy and the current guidance rather than from a previous project.

The energy hierarchy still structures the statement. Be lean, be clean, be green, be seen. What changes on a listed building is that the first step is constrained, so the second and third have to carry more, and the fourth earns its place because a monitored building tells you what the model could not.

Fabric measures that are usually acceptable

Work from the inside out and from the invisible to the visible. The following measures are frequently acceptable on a listed building, subject always to the specific fabric and to the conservation officer's view.

• Loft insulation at ceiling level, where there is no historic plaster ceiling at risk and the timbers can be inspected afterwards.
• Insulation to a suspended timber ground floor, taken up from above during other works.
• Draughtproofing of windows and doors, using discreet brush or compression seals rather than surface-applied strips.
• Secondary glazing, slim framed and set back, which is reversible and often the single most effective window measure.
• Reinstating shutters, and heavy lined curtains with pelmets.
• Chimney balloons or dampers in unused flues.
• Insulation behind later, non-original linings, where hygrothermal risk has been assessed.
• Roof insulation at rafter level where slates are already being stripped for repair.

Two of these do more work than the rest. Draughtproofing plus secondary glazing addresses the dominant heat loss path in most listed dwellings, which is air leakage through and around historic joinery, and neither harms the fabric if detailed carefully.

Measures that require consent and often fail

The list of refusals is short and predictable.

Replacing historic glass with sealed units in original frames removes the glass and usually the glazing bars. Full window replacement in uPVC or aluminium is refused as a matter of course. External wall insulation changes every elevation, junction and reveal, and on a listed building it is almost never acceptable, which is a different calculation from an unlisted house in a conservation area where external wall insulation is judged on appearance.

Internal wall insulation on solid walls is the interesting case, because it fails on two grounds at once. Where there is decorated plaster, cornice or panelling, it harms special interest. And on a solid wall built to dry out inwards, adding an impermeable layer raises interstitial condensation and decay risk at embedded timbers. BS 5250 and the hygrothermal assessment it points to are the technical answer, and the honest outcome is often that the measure is not worth the risk.

Spray foam in a roof space deserves a paragraph of its own. It obscures the timbers from inspection, traps moisture, and is difficult to remove. Several lenders decline properties that have it.

Services and controls as the main lever

When fabric is constrained, services do the heavy lifting. This is where a listed building statement should spend most of its length.

1. Heat source. An air source heat pump needs an external unit, and siting is a listed building consent question as much as a planning one. Permitted development rights do not remove the need for listed building consent, so a Part 14 class does not help you.
2. Emitters. A heat pump at a low flow temperature needs larger emitters or underfloor heating, and in a listed interior the achievable emitter size may cap the whole strategy. Say so.
3. Zoning and controls. Independent zones per floor, room thermostats, weather compensation and time control give real savings in a building that will never be airtight.
4. Hot water. Cylinder insulation, secondary return losses and pipe runs through unheated spaces.
5. Lighting and appliances, which matter more once the heating load is reduced as far as it can be.

Record the flow temperature the emitters can achieve and the heat loss you have actually calculated. A statement that asserts a heat pump is viable without that calculation invites a challenge from the conservation officer and from the client's engineer.

Renewables on a designated asset

Solar photovoltaics on a listed building turn on visibility and on fixing. A rear roof slope hidden from public view, panels laid in a single rectangle with matching flashings, and fixings into batten rather than through historic rafters, is a scheme that sometimes succeeds. A front elevation array does not.

Ground-mounted arrays in a curtilage raise setting questions rather than fabric ones, and outbuildings with modern roofs are frequently the answer nobody looked at. Where the roof covering is Welsh slate or handmade clay tile, in-roof systems that remove the covering are harder to justify than on-roof systems that sit above it.

Heat networks, where one is available, sidestep the appearance problem entirely and should be checked before anything else.

Justifying a shortfall against policy targets

This is the section that decides the application. Build it as a table, not as prose.

For each policy requirement, state the measure considered, what was done, what was rejected, the heritage reason for rejection with reference to the list entry and the significance assessment, and the residual effect on the target. Then state the overall position: the percentage reduction achieved, the reduction the policy seeks, and the gap.

Where local policy provides for a carbon offset payment to cover a shortfall, price it and offer it. Where it does not, the argument is that the statutory duty and the heritage policy of the National Planning Policy Framework outweigh full compliance with a numerical target, and that argument is much stronger when every acceptable measure has visibly been taken.

Whole life carbon is the quiet ally here. Retaining and repairing existing fabric avoids the embodied carbon of replacement, and a whole life carbon assessment often shows a repaired historic building outperforming a replacement over a 60 year period. Use it where the policy framework allows.

Illustrative example: a Grade II early nineteenth century townhouse, single glazed sashes, solid brick walls. Secondary glazing throughout, full draughtproofing, loft and suspended floor insulation, an air source heat pump in a rear lightwell with oversized radiators, three heating zones, and photovoltaics on a flat roof extension not visible from the street. The statement quantified a shortfall against the local target and set out eight rejected measures with the heritage reason for each. Approved with a condition on the external unit's acoustic housing.

Documenting the balance for the decision maker

Keep the energy statement and the heritage statement consistent. They are read together, and a contradiction between them is the thing an objector will find.

Overheating is the other consistency check. Secondary glazing, draughtproofing and reduced ventilation raise the overheating risk in a building that previously leaked its way to comfort, and an overheating risk assessment that models the building as altered avoids a problem arriving after completion.

Finish with a short monitoring commitment. Be seen is the step that is easiest to offer and rarely offered: metered energy use for two years, reported to the authority, which turns a contested assumption into evidence for the next application on a similar building.

Draft the energy statement for your scheme on PlanScope, then have it reviewed alongside the heritage assessment before submission.

This is general guidance, not legal advice. Listed building works need advice from a conservation professional and, for services design, a qualified engineer. Check the position with your local planning authority 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.