Gas boilers in an energy statement and where policy stands

Gas boiler planning policy is now the awkward part of most energy statements, because the national building standard and a growing number of local plans pull in different directions. Building Regulations still permit a gas boiler in a new dwelling. Adopted local plan policies in many authorities effectively do not, either by setting a carbon reduction target that gas cannot reach or by requiring connection to a heat network or a heat pump solution. The energy strategy has to reconcile the two, and it is the local policy that decides the application.

Where the national position sits

The Part L uplift that took effect in June 2022 tightened the target emission rate for new dwellings and changed the notional building against which compliance is measured. A gas boiler scheme can still comply, though it has to work harder on fabric, ventilation and low-carbon supplementary measures to do so.

The Future Homes Standard has been consulted on with the stated intention of moving new homes away from fossil fuel heating, and the commencement date and final content have moved more than once. Treat it as announced and not yet in force, check the current position on gov.uk before you write, and state in the energy statement which edition of Part L the calculations were run against. Transitional arrangements matter here: a scheme with a commencement date inside a transition window may be assessed against the earlier edition, and that should be stated rather than assumed.

Nothing in the national position requires an applicant to justify a gas connection. Local policy frequently does.

Local plan policies that restrict new gas

Section 1 of the Planning and Energy Act 2008 lets a local plan include policies requiring a proportion of the energy used in development to come from renewable sources on site and setting energy efficiency requirements. That is the statutory hook most authorities cite.

The policies fall into recognisable families.

• A percentage carbon reduction beyond the Building Regulations target, which a gas boiler scheme will usually miss without an unreasonable amount of photovoltaic array.
• A requirement to follow an energy hierarchy, with the London Plan's be lean, be clean, be green and be seen sequence the widest-known version, and policy SI 2 the relevant policy for major development in London. Where the on-site target is not met, a carbon offset payment secured by obligation makes up the shortfall. Check the current Greater London Authority energy assessment guidance for the baseline and the offset price, because both are revised.
• A heat network requirement, obliging connection where the site falls inside a designated heat network priority area, or safeguarding a future connection point where a network is planned.
• An explicit prohibition on new fossil fuel heating systems, which a handful of authorities have adopted and more have proposed through plan review.

Read the policy wording rather than the supporting text. A policy that says development should achieve a target is weaker in practice than one that says development will only be permitted where it does.

Hybrid systems and how they are assessed

Hybrid arrangements pairing a heat pump with a gas boiler for peak demand are offered as a compromise and are assessed sceptically, for a defensible reason: the modelled split between the two heat sources is an assumption, and occupant behaviour and control settings decide the real one.

If you propose a hybrid, model the split explicitly, say what proportion of annual heat demand each source carries, and show the calculation. Then explain the control strategy that delivers it. An officer reading a hybrid case wants to know what stops the boiler doing most of the work on a cold week in January.

Where the reason for the hybrid is peak electrical capacity rather than carbon, say that plainly and evidence it. That is a stronger argument than an efficiency claim.

Electrical capacity and why it drives the answer

The practical constraint on all-electric heating is often the connection, not the plant. A scheme moving from gas boilers to heat pumps raises the diversified electrical load per dwelling substantially, which can turn a simple service connection into a new substation, a reinforcement contribution and a programme risk.

Get the distribution network operator's budget estimate early, because the answer changes the layout: a substation needs a site, access and a lease. Record the position in the Energy Statement and, where a substation is proposed, in the Utilities Assessment as well, so the two documents agree.

Heat pumps also change the overheating picture, because the fabric and glazing strategy that suits a low-temperature system interacts with Part O. An Overheating Risk Assessment run on the final glazing specification, rather than an early one, avoids a late redesign.

Existing buildings and replacement plant

Replacing a boiler in an existing house is not usually development at all, so planning policy does not reach it. The exceptions are worth knowing.

A flue on a listed building affects the character of the building and may need listed building consent. External plant in a conservation area can need permission where it is on a principal elevation fronting a highway. An air source heat pump on a dwelling is permitted development under Class G of Part 14 of Schedule 2 to the General Permitted Development Order 2015, subject to conditions on siting, scale and compliance with the relevant planning standards, and those conditions have been amended, so read the current text rather than a summary.

Commercial conversions are a different problem, because the existing heat source is often a dated gas system and the conversion triggers an energy assessment against current policy. The cost of the change sits in the viability case.

Evidencing a case for gas where it is still proposed

Sometimes gas remains the proposal. The evidence that makes that arguable, in rough order of weight:

1. A written distribution network operator response showing the electrical capacity is not available within the development programme, with the reinforcement cost and timescale.
2. A carbon comparison over the plant's expected life, using the published grid carbon factors, that shows what the gas option actually costs in emissions against the alternatives assessed.
3. A safeguarding commitment: pipework, plant space, riser provision and electrical capacity designed so the building can convert to low-carbon heat later without opening up the structure.
4. Where the site sits in a heat network priority area, a network operator's written position on connection timing.

An assertion that heat pumps were considered and found unsuitable, with no supporting figures, is what gets conditions imposed instead. And a carbon comparison that stops at the day of completion misses the point of the policy.

Conditions restricting a future connection

Authorities increasingly attach conditions about heat supply, and they have to meet the six tests in the Planning Practice Guidance on conditions. Those most often seen require a scheme for connection to a future heat network, require the plant specified in the approved energy statement and no other, or require submission of an as-built report against the modelled performance.

The be-seen style monitoring condition is the one to read carefully. It commits the developer to reporting actual performance after occupation, and the reporting obligation can outlast the developer's interest in the site. Agree who holds it before the decision notice is issued.

Draft your Energy Statement in minutes and then send it for professional review, or read the all-electric new homes decision for a worked comparison. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance rather than legal advice, so check the position with your local planning authority or a qualified professional before relying on it.