Reporting regulated and unregulated emissions separately
Part L targets and carbon offset payments bite on regulated emissions only. Reporting both categories in one table, with the policy figure labelled, stops the most common review comment.
Regulated and unregulated emissions have to be reported as separate lines, because they are measured by different means and only one of them is what a compliance target or an offset payment actually bites on. Regulated emissions come from the fixed building services controlled by Part L of the Building Regulations. Unregulated emissions come from everything else the occupier plugs in or lights a hob with. Merge the two into a single percentage and you will produce a number no officer can check and no condition can secure.
What each category covers
Regulated energy is the set of end uses the National Calculation Methodology models: space heating, space cooling, domestic hot water, fixed ventilation and its auxiliary energy, and fixed internal lighting. Those are the loads a designer controls through fabric, plant selection and controls, so those are the loads Part L regulates.
Unregulated energy sits outside that boundary. In practice it means cooking appliances, small power and plug loads, lifts and escalators, server rooms, external and car park lighting where it is not fixed internal lighting, and process energy in a commercial building.
The split is not about how much carbon each produces. In a well-insulated flat with a heat pump, unregulated energy can be the larger share of the operating total. It is about who controls it, and a planning condition cannot control what a future tenant buys from a retailer.
Why compliance targets use regulated emissions only
Part L 2021, in force since 15 June 2022, sets its improvement against a notional building and measures only regulated emissions. New dwellings are expected to deliver around a 31 per cent reduction in carbon emissions against the previous 2013 standard, and new non-domestic buildings around 27 per cent, both figures being regulated-only comparisons using the SAP 10.2 and SBEM emission factors.
That matters when you quote a saving in an Energy Statement. A reduction expressed against the Part L notional building is a regulated-emissions figure by definition. Writing it as a saving on total emissions is simply wrong, and an officer with an energy consultant on retainer will spot it.
BREEAM works the same way. The Ene 01 credit draws on the National Calculation Methodology output, so the energy performance it rewards is regulated performance, which is one reason a BREEAM rating and a planning policy target do not always move together.
Where a policy reaches unregulated emissions
Some policy does look beyond the Part L boundary, and you should know which parts.
The London Plan 2021 energy hierarchy, Be Lean, Be Clean, Be Green, Be Seen, requires major schemes to report regulated and unregulated emissions in the same tables at baseline and after each stage, even though the net zero-carbon target and the borough offset payment apply to residual regulated emissions. The Greater London Authority's energy assessment guidance sets out the table format and is periodically revised, so work from the current version rather than a table copied from an earlier scheme.
Whole life carbon reporting reaches further still. Under the RICS Whole Life Carbon Assessment standard, second edition 2023, operational energy in module B6 covers both regulated and unregulated use over the assessment period, which is why a Whole Life Carbon Assessment and an energy statement will legitimately show different operational figures for the same building. Say so in both documents rather than leaving a reviewer to find the discrepancy.
Post-occupancy monitoring policies, where a council has them, almost always measure metered energy, which is the total. A commitment to report metered performance against a modelled regulated figure is a commitment to an unfavourable comparison.
How mixing the two distorts a percentage saving
The arithmetic is easy to get wrong in the direction that flatters the scheme, and easy to get wrong in the direction that sinks it.
If unregulated emissions are added to both the baseline and the proposed case without any change between them, the denominator grows while the saving does not. A design achieving a 40 per cent regulated reduction might show as something closer to 25 per cent on a total-emissions basis, purely because of the larger denominator. Nothing about the building changed.
The reverse error is worse. Applying an improved electricity carbon factor to unregulated loads, while leaving the baseline unregulated loads on an older factor, creates a saving the design did not produce. That kind of figure has been unpicked at appeal, and the whole energy statement loses credibility with it.
| Line | Baseline | After measures | Reduction |
|---|---|---|---|
| Regulated emissions | reported | reported | the compliance figure |
| Unregulated emissions | reported | reported if changed | usually nil |
| Total | reported | reported | contextual only |
Keep the reduction column empty on the total row if nothing in the unregulated column has moved. An empty cell is more honest than a diluted percentage.
Presenting both in one table
The format that survives review is a single table with regulated, unregulated and total as three rows, repeated for each stage of the hierarchy, in tonnes of CO2 per year to one decimal place, with the emission factors and the calculation tool version named in a footnote.
Add a short note under the table stating which row the policy target applies to. Two sentences. It removes the most common review comment before it is written.
Where a scheme has several uses, split the table by use rather than reporting a blended figure. A logistics building with a small office is a case in point, and the approach we set out for energy statements on warehouse and logistics schemes applies equally to mixed residential and commercial blocks.
Offset calculations and which figure applies
Carbon offset payments, where a borough or district operates a fund, are calculated on residual regulated emissions after on-site measures, multiplied by a price per tonne and a period, commonly 30 years. The price is set by the authority and reviewed, so take the figure from the current published guidance or charging document rather than a precedent scheme.
Three practical points follow. Use the regulated residual, not the total. State the emission factor set behind that residual, because a change of factor changes the payment. And show the calculation in full, including the tonnes, the price, the period and the arithmetic, so the section 106 drafter can lift it.
If your scheme includes combined heat and power, the emission factors interact with the air quality case as well, and the tensions that creates are set out in our piece on combined heat and power and the air quality objection.
Answering an officer who asks for a single number
Officers ask for one number because committee reports have limited room. Give them the regulated percentage, labelled as such, and a second sentence giving the residual tonnes to be offset. That is two numbers a committee can use and a condition can secure.
Resist the total-emissions percentage unless the policy you are being assessed against asks for it. If it does, give both, with the regulated figure first, and explain in one line why they differ. And keep the wording identical across the energy statement, the sustainability statement and the planning statement, because inconsistency between those three is one of the more common reasons an energy condition gets drafted more tightly than you wanted.
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, and an energy statement relying on SAP or SBEM output needs a suitably qualified assessor to run and sign off the modelling.
Enter your postcode on PlanScope to see which energy and sustainability reports your scheme is likely to need.
Frequently asked questions
What counts as regulated energy under Part L?
Regulated energy covers the fixed building services the National Calculation Methodology models: space heating, space cooling, domestic hot water, fixed ventilation with its auxiliary energy, and fixed internal lighting. These are the loads a designer controls through fabric, plant and controls. Everything else the occupier brings, such as cooking and plug loads, is unregulated and falls outside the Part L calculation.
Do carbon offset payments use regulated or total emissions?
Offset funds are calculated on residual regulated emissions remaining after on-site measures, multiplied by a price per tonne and a period, commonly 30 years. The price is set by the authority and reviewed periodically, so take it from current published guidance rather than a precedent scheme. Show the tonnes, the price, the period and the arithmetic in full.
Why does my whole life carbon figure differ from my energy statement?
Module B6 of the RICS Whole Life Carbon Assessment standard covers operational energy including unregulated use over the whole assessment period, while an energy statement reports regulated emissions against a Part L notional building. The two are measuring different boundaries over different periods. Explain the difference in both documents rather than leaving a reviewer to discover it.
Can a planning condition control unregulated emissions?
Only indirectly. A condition can require fixed plant, metering, external lighting specifications or a post-occupancy reporting regime, but it cannot control which appliances a future tenant buys. That is the practical reason compliance targets stop at the Part L boundary, and why commitments about unregulated energy are better framed as monitoring than as a cap.
What reduction does Part L 2021 expect?
Part L 2021, in force since 15 June 2022, expects around a 31 per cent carbon reduction for new dwellings and around 27 per cent for new non-domestic buildings, both measured against the previous 2013 standard. Both are regulated-only comparisons produced by SAP or SBEM. Quoting either as a total-emissions saving misstates what the calculation did.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.