The carbon offset and monitoring sections of an Energy Statement

Carbon offsetting is the last stage of an Energy Statement, not a shortcut through the earlier ones. The carbon offset section of an Energy Statement quantifies the regulated carbon the scheme still emits after the fabric, the plant and the renewables have done everything they reasonably can, converts that residual into a payment or an off-site measure, and shows how it will be secured. The monitoring section then commits the development to reporting what it actually emits once people are living in it.

Both sections are short. Both are read closely, because they are where a case officer checks whether the earlier numbers add up.

Where offsetting sits in the hierarchy

The energy hierarchy used across England and formalised in London is be lean, be clean, be green, be seen. Reduce demand through fabric and form. Supply energy efficiently. Generate renewable energy on site. Then monitor what happens in use.

Offsetting is not a step in that sequence. It deals with what is left over after step three, and a scheme that reaches for offsetting before exhausting the on-site options will be told to go back. The order matters in the drafting as well: present the offset figure as the arithmetical residual of the stages above it, with the intermediate carbon figures shown, so an officer can see nothing was skipped.

Where an authority has a net zero carbon policy for major development, it will usually set a minimum on-site reduction against the Building Regulations baseline before any offset is accepted. Take that figure from the adopted plan or its guidance rather than from a previous scheme, because the baseline moved with the Part L 2021 uplift and local policies were written against different versions of it.

Calculating the residual

The calculation covers regulated emissions: space heating, hot water, cooling, ventilation, lighting and auxiliary energy. Unregulated emissions from cooking and appliances sit outside the Building Regulations calculation and outside most offset policies, so say which basis you are using.

Three numbers drive the section.

The baseline emissions, calculated to the version of Part L applicable to the application, using SAP for dwellings and SBEM or dynamic simulation for non-domestic buildings.

The residual emissions after the lean, clean and green stages, from the same model.

The shortfall against the policy target, expressed in tonnes of carbon dioxide per year.

That annual shortfall is then multiplied by the period the policy applies, commonly 30 years, and by the price per tonne the authority uses. The Greater London Authority publishes a recommended price in its energy assessment guidance and London boroughs may set their own, and authorities outside London that operate offset funds publish rates in a supplementary planning document or a charging schedule. Prices are revised, so cite the current published figure rather than carrying one forward.

Securing the payment

An offset payment is almost always secured through a section 106 obligation rather than a condition, because it is a financial contribution. Four drafting points decide whether it works.

The trigger. Before first occupation is normal, and on a phased scheme the obligation should be split by phase so the payment follows delivery.

The recalculation mechanism. Where the as-built performance differs from the design stage model, the obligation should say whether the payment is recalculated and at whose risk.

Indexation. A fixed sum agreed at permission and paid four years later has lost value, so expect index linking.

The destination. Authorities usually direct payments to a ring-fenced carbon offset fund, and the obligation should say what the money may be spent on.

Where an authority accepts off-site carbon measures instead of a payment, the obligation needs to identify the measures, the delivery body and the verification. That is harder to draft and slower to agree, and most applicants take the payment route for that reason.

Monitoring and reporting after completion

The be seen stage asks for actual performance rather than modelled performance, and it operates in three reporting rounds: as designed at the planning stage, as built after construction, and in use annually for a stated number of years once the building is occupied.

What has to be submitted is more specific than people expect. Modelled and then metered energy use by end use, the renewable generation actually achieved, the emissions resulting, and an explanation where the in-use figures diverge from the design. That last item is the point of the exercise. A development reporting in-use energy well above its design figure is useful information to the authority even though it is uncomfortable for the applicant.

Meter strategy is therefore a design decision and not an afterthought. Separate metering of landlord services, individual dwelling consumption, and renewable generation is what makes reporting possible. Retrofitting sub-metering after handover is expensive and frequently incomplete, so the Energy Statement should state the metering strategy explicitly.

Who is responsible once the units are sold

This is the practical weakness in the whole regime. The planning obligation binds the land, so the duty persists, but the party able to collect the data changes.

On a build to rent or a commercial building with a single owner, reporting is straightforward. On a scheme sold plot by plot, the developer loses access to the meters, and the management company inherits a reporting duty it was never briefed on and has no budget for.

Three things reduce that risk. Name the responsible party for each reporting round in the obligation, including the successor after disposal. Put the data collection duty into the management company's service charge schedule and its handover pack. And specify half-hourly data collection from landlord and communal meters, which can be read remotely rather than relying on occupier cooperation.

Honest uncertainty: enforcement of in-use reporting obligations is patchy, and an obligation that nobody chases delivers nothing. Writing it well is still the right thing to do, and it costs almost nothing at drafting stage.

Keeping the figures consistent

The offset figure in the energy statement has to agree with everything else in the submission. Four documents commonly disagree.

The sustainability or energy summary in the planning statement, where an earlier iteration of the figures survives.

The sustainability statement, which often quotes a percentage reduction from a previous model run.

The whole life carbon assessment, where the operational energy modules should reconcile with the Energy Statement's regulated figures.

The architect's roof plan, where the photovoltaic area assumed in the model exceeds the area actually available once plant, access zones and overshadowing are allowed for.

Run a single check before submission: one table of carbon figures, one source model, one date, referenced from each document rather than retyped into each. The same discipline applies to a BREEAM credit strategy, where energy credits depend on the same model outputs.

Councils expect a suitably qualified author for energy and carbon modelling and professional review is strongly advised before submission. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.