Regulated and unregulated energy in an energy statement

Regulated energy is what Building Regulations control: space heating and cooling, hot water, ventilation, fixed internal lighting, and the pumps and fans serving them. Unregulated energy is everything the occupier brings or switches on, from the oven and the fridge to IT equipment, external lighting and, in most non-domestic models, the lifts. Getting regulated and unregulated energy straight matters because Part L compliance and almost every local policy target are set against regulated emissions alone, while the bill the occupier pays covers both.

That gap is where energy statements come unstuck. An officer reading "a 35 per cent reduction" wants to know 35 per cent of what, and a statement that quietly mixes the two categories in one table invites a request for further information.

What each category covers

Part L works from the idea of fixed building services. If a service is installed as part of the building and falls inside the Approved Document L compliance calculation, its energy is regulated. For a dwelling that gives a short list: space heating, space cooling, domestic hot water, mechanical ventilation, and fixed lighting.

Everything else is unregulated. In a house that means the hob, the washing machine, the television and every charger left plugged in. In an office it means small power at the desk, the comms room, catering, external and car park lighting, and usually lifts and escalators.

Two loads sit awkwardly in between. Electric vehicle charging is occupier load, yet its diversified demand drives the incoming supply capacity, so it belongs in the load summary even though it sits outside the emissions target. Landlord-controlled corridor lighting in a block of flats is regulated within the non-domestic assessment of the common parts, while the flats themselves are modelled under the domestic methodology.

A quick test

Ask whether the building could be handed over without it. Boiler, no. Toaster, yes. The toaster is unregulated.

Why policy targets regulated emissions

The designer controls the fixed services and the fabric. The designer does not control how many freezers a tenant installs. Building Regulations therefore compare a proposed building against a notional building of the same size and shape, built to a defined specification, and the comparison only works if both sides count the same things.

That comparability is why planning policy borrows the Part L baseline rather than inventing one. London Plan 2021 Policy SI 2 asks major development to be net zero-carbon and sets a minimum on-site reduction of 35 per cent beyond Building Regulations, and that percentage is a regulated-emissions figure. Local plan policies outside London usually copy the same structure, sometimes with a different percentage or an earlier Part L baseline, so check the adopted wording before you fix a target in the design.

The practical consequence is that a scheme can hit its planning target and still hand the occupier a large electricity bill, because the loads driving that bill were never in scope.

Where unregulated loads still matter

Four places, and none of them are optional.

The incoming electrical supply is sized on total connected load, so understating small power and vehicle charging produces a capacity request the distribution network operator later has to revise.

Overheating modelling uses internal gains, and a good share of those gains are unregulated equipment. A CIBSE TM59 assessment for dwellings or a Part O compliance check will look thin if it assumes low equipment gains that the room layout cannot support.

Whole life carbon reporting includes operational energy as a separate module, and an assessment that counts only regulated energy understates the operational stage. If your scheme needs a Whole Life Carbon Assessment, agree the operational energy basis with the assessor before either document is drafted, so the two do not contradict each other.

Post-occupancy monitoring measures metered energy, which is inherently both categories together. Predicted regulated figures and metered total figures are not comparable, and saying so in the statement saves an argument two years later.

How each is modelled

For dwellings, the Standard Assessment Procedure produces the Dwelling Emission Rate and compares it with the Target Emission Rate, alongside primary energy and fabric energy efficiency rates. SAP does calculate appliance and cooking energy for other purposes, including the EPC, but that energy is excluded from the emission rate comparison.

For other buildings, the National Calculation Methodology runs through SBEM or an approved dynamic simulation model and gives a Building Emission Rate against a Target Emission Rate. Again the target covers fixed services only.

Unregulated energy needs a different tool. CIBSE TM54 sets out how to estimate operational energy at design stage, including equipment, catering and vertical transport, and it is the method most reviewers expect to see named when a statement quotes a total energy figure.

Name the software and version, the weather file and the assessment year. A reviewer who cannot tell which version of SAP produced a number cannot check it.

Effect on a stated carbon reduction

The arithmetic below is illustrative, using round figures to show the method rather than any real building.

Take a baseline of 40 tonnes of carbon dioxide a year regulated and 25 tonnes unregulated. A 35 per cent on-site cut applied to the regulated figure takes it to 26 tonnes. Total emissions fall from 65 to 51 tonnes, which is a 21 per cent cut overall. Both numbers are true. Only the first answers the policy question, and only the second tells the client what to expect from the meters.

Write both, label both, and never let the larger percentage appear next to the word "total" without a qualifier. And if the scheme relies on an offset payment for residual regulated emissions, say which figure the payment is calculated on.

Monitoring after occupation

London Plan Policy SI 2 carries a reporting stage covering predicted and in-use energy performance for major development, which is where the regulated and unregulated split stops being a modelling convention and starts being a measured difference. Sub-metering has to be designed in early to separate landlord services from tenant equipment, because retrofitting meters into a finished riser is expensive and often incomplete.

Outside London the same discipline is worth adopting voluntarily, and some authorities now attach an energy monitoring condition to major consents. Check the current Greater London Authority guidance for the reporting format, because it has been revised more than once.

Reporting both without confusion

A clean Energy Statement does five things with these two categories. It defines them in one short paragraph. It gives separate baseline and proposed figures for each. It states which figure the policy target applies to. It flags any load that a reader might reasonably classify differently, such as lifts. And it keeps the same numbers in the Sustainability Statement so the two documents agree.

The commonest error is a single summary table with one "total emissions" row and a percentage that came from the regulated calculation. The second commonest is a proposed regulated figure compared against an older Part L baseline than the one the authority's policy names.

PlanScope drafts energy statements with the regulated and unregulated split set out as separate reporting lines and inserts a "to be confirmed" flag wherever the modelling output has not been entered, so a reviewer can see what is missing rather than reading a plausible invented number. Enter your postcode on PlanScope to see which reports your site is likely to need, then send the draft to your energy assessor to populate and check.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.