Net zero carbon policies in local plans and the offset payment

A net zero carbon policy in a local plan almost never means a building with no emissions. It means a defined percentage reduction achieved on site, measured against the Building Regulations baseline, with the remaining shortfall paid for in cash to a carbon offset fund. Understanding that structure is what lets you price the policy at the start of a scheme rather than at the section 106 stage.

The model came from London and has spread. A major application is required to reduce regulated carbon emissions by a stated percentage beyond the national baseline, to demonstrate it through an energy strategy following a four-stage hierarchy, and to make a payment covering the residual tonnes over a 30 year period where the on-site target is not met in full.

How a plan level carbon policy is usually worded

Read any such policy and you will find four components.

A target, expressed as a percentage improvement on the regulated emissions calculated under the current Part L methodology, and sometimes as an absolute energy use intensity figure in kilowatt hours per square metre per year.

A hierarchy, requiring a minimum part of the saving to come from fabric and passive design before any credit is taken for low carbon technologies. In the London formulation this is the be lean, be clean, be green, be seen sequence, and the first stage carries its own minimum percentage.

A fallback, allowing the shortfall between the target and what is achieved to be met by a financial contribution.

And a verification requirement, asking for as-built evidence after completion rather than taking the design stage calculation on trust.

The order matters. A scheme that hits the headline percentage entirely through photovoltaic panels, with no fabric improvement, fails a policy with a minimum lean stage even though the total looks compliant.

The on site reduction required before any offsetting

This is where most negotiation happens, because the on-site figure is the expensive one and the offset is the easy escape. Policies are drafted to stop that escape being used as the first option.

Three questions decide what you have to deliver on site. What baseline applies, which depends on the version of the Building Regulations in force when the building notice or initial notice is given rather than when the application is submitted. Whether the target applies to regulated emissions only, or to unregulated energy as well. And whether the minimum fabric stage is expressed as a percentage of the total saving or as a standalone improvement.

Get those three wrong and the energy strategy answers a different question from the one the policy asks. An Energy Statement that sets out the baseline assumptions explicitly, stage by stage with a table of emissions at each, is far harder to argue with than one that reports a single headline percentage.

Heat is usually the binding constraint. A policy with a meaningful fabric stage and a restriction on fossil fuel heating pushes schemes towards heat pumps, which in turn raises questions about plant space, external unit noise and overheating, so the carbon policy quietly reshapes the design well beyond the energy chapter. Logistics and industrial buildings have their own version of this problem, covered in energy statements for warehouse and logistics schemes.

Calculating and indexing the offset payment

The arithmetic is simple and the inputs are where the argument lies.

The price per tonne is a local decision, usually taken from recommended guidance and sometimes uplifted. Authorities review these rates, so check the figure currently adopted by the authority you are dealing with rather than one quoted in an older report, and check whether the rate is indexed between the date of the obligation and the date of payment. An un-indexed rate on a scheme built out over six years is worth arguing for.

Two points catch developers out. The payment is calculated on regulated emissions over three decades, so a small annual shortfall becomes a six-figure contribution on a large scheme. And the calculation is normally done at design stage and then recalculated against the as-built position, which means the obligation has to say what happens if the as-built figure is worse than predicted.

Securing the payment through a planning obligation

Carbon offset contributions are secured by a section 106 agreement or a unilateral undertaking, not by condition, because a condition cannot require a payment.

That brings the statutory tests into play. An obligation may only be taken into account where it is necessary to make the development acceptable in planning terms, directly related to the development, and fairly and reasonably related in scale and kind. A carbon contribution tied to a specific adopted policy and calculated by a published formula satisfies those tests comfortably. A contribution to a general sustainability fund with no methodology does not, and that distinction is worth raising where an authority has a policy aspiration but no adopted mechanism.

Three drafting points are worth your solicitor's time. Trigger the payment at a sensible point, normally first occupation rather than commencement, since the as-built figure is not known earlier. Build in a mechanism for recalculation if the scheme is amended under section 73. And set out what happens to the money if it is not spent, because some agreements include a clawback after a fixed period.

Monitoring, verification and review

The verification stage is where schemes fail quietly. A policy asking for as-built evidence usually wants the final compliance calculation for each dwelling or building, submitted before occupation, alongside evidence that the installed systems match the design.

What goes wrong is substitution during construction. A specified heat pump becomes a different model, a glazing specification changes on cost grounds, a photovoltaic array shrinks to fit the roof around plant that was added late. Each change is small and the cumulative effect moves the as-built figure below the design figure, at which point the offset payment recalculates upwards.

A design team that tracks the carbon position through construction, in the same way a Whole Life Carbon Assessment tracks embodied emissions through procurement, avoids finding out at handover. Where a review clause exists, read it carefully, because some are drafted so that only an upward adjustment is possible.

Where policies have been watered down at examination

Not every carbon policy survives examination in the form the council proposed, and the reasons are worth knowing because they shape what an inspector will accept.

Local planning authorities have a statutory power to set energy efficiency requirements for development through plan policies, and that power has limits that have been argued over for years. A ministerial statement from 2015 on housing standards is still cited as restricting how far residential energy policies can go beyond national requirements, and its continuing effect remains contested. The Future Homes Standard adds another layer, since the government has signalled an intention to reduce the scope for local variation once the national standard takes effect. As at October 2026 that position needs checking against the current national policy and any ministerial statement, because it has moved more than once.

Two patterns recur at examination. Policies with absolute energy use intensity targets have survived more readily where the evidence base included a viability test of those specific targets. Policies requiring certification to a particular private standard have fared worse, because inspectors treat a requirement to buy a commercial certificate differently from a performance requirement.

Testing the policy against viability

A plan policy requiring both a high on-site reduction and an offset payment has a cost, and that cost should have been tested at plan-making stage through whole plan viability work. Where it was, the policy is hard to resist on viability grounds at application stage.

Where it was not, or where site-specific costs are abnormal in a way that can be evidenced, a Viability Assessment can be used to argue for a reduced contribution. National guidance expects such assessments to be the exception, to be made publicly available, and to use benchmark land value rather than the price actually paid. Councils expect a suitably qualified author, and professional review is strongly advised.

The practical advice is less about argument than sequencing. Price the on-site measures and the likely offset payment during the appraisal, before the land deal, because the policy is published and the formula is public. A carbon contribution discovered during section 106 negotiation is a cost that has nowhere to go.

Enter your postcode on PlanScope to see which energy and sustainability documents your scheme is likely to need.

This is general guidance, not legal advice; check the adopted policy and the current offset rate with the 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.