The energy hierarchy in a London energy statement

Be lean, be clean, be green, be seen is the order in which a London energy statement has to argue its case, and the order is not decorative. The Greater London Authority expects demand reduction to be exhausted before efficient supply is claimed, and efficient supply before renewables are counted, with the residual shortfall offset. The fourth stage, added by the London Plan 2021, obliges major schemes to report measured energy performance after completion rather than stopping at a design stage model. Miss any stage and the statement comes back from the GLA with a comment that costs weeks.

Where the hierarchy comes from and what it governs

The hierarchy sits in the London Plan 2021 energy policies, which apply to major development across Greater London and are applied most forcefully to applications referable to the Mayor under the Town and Country Planning (Mayor of London) Order 2008. Boroughs apply the same policies to schemes below the referral thresholds through their own local plans.

Two figures drive most of the work. Major development is expected to be net zero-carbon, and to achieve a minimum on-site reduction beyond the Building Regulations baseline, with a separate expectation that part of that saving comes from fabric and demand measures alone before any supply technology is counted.

The baseline moved when Part L 2021 came into force, and the Mayor's energy assessment guidance was reissued to deal with it. Check which version of that guidance your borough is working to before the modelling starts, because running the assessment against the wrong baseline is the single most expensive error in this document.

Be lean and the evidence for demand reduction

The lean stage covers fabric, form, glazing ratios, thermal bridging, airtightness and controls. It is assessed on what the building needs, before anything is plugged into it.

Weak statements assert a fabric first approach and then present a single modelled result. Strong ones show the iteration. List the U-values and the air permeability actually used in the model, say what was tested and rejected, and give the space heating demand and the percentage saving attributable to this stage on its own.

Glazing is where the argument usually turns. A fully glazed south elevation drives cooling demand up and then needs mechanical cooling to fix it, which the next stages have to carry. If the architecture demands the glass, say so and show the compensating measures rather than leaving the reviewer to infer them. Overheating modelling belongs alongside this, and an Overheating Risk Assessment should use the same geometry and the same assumptions as the energy model.

Be clean and the heat network question

The clean stage asks how heat is supplied. London policy sets a heating hierarchy that looks first to connection with an existing or planned district heating network, then to site wide systems, then to individual solutions.

For a site inside or near a network area, the statement needs evidence of contact with the network operator, the response, and the connection point. A sentence saying no network exists nearby is not evidence. Where connection is impractical, the scheme is usually expected to be built to be connectable later, with plant space and a route safeguarded.

Communal heat pumps have largely displaced gas combined heat and power in new residential schemes, and the gas engine that used to sit in this stage now tends to create more problems than it solves on air quality grounds. The statement should reflect that rather than repeating an assessment written for a different decade.

Be green and the roof space argument

The green stage covers on-site renewable generation, in practice mostly photovoltaics and heat pumps where they have not already been counted at the clean stage.

Roof space is finite and contested. Plant, lift overruns, terraces, biodiverse roofs and photovoltaic arrays all want the same surface. Reviewers look for a roof plan showing the allocation, the array area in m², the assumed orientation and pitch, and the annual yield with the tool used to calculate it.

Where the biodiverse roof and the array compete, a combined biosolar roof is usually the answer and should be drawn rather than described. This is also the point where a Green Infrastructure Plan and the energy statement must agree with each other, because contradictory roof plans in two documents of the same application are noticed.

Be seen and the monitoring obligation

The monitoring stage is the one applicants underestimate. It commits the development to reporting actual energy performance through the Mayor's reporting platform at defined points, typically at the design stage, on completion, and then in operation for a period of years after occupation.

Three consequences follow at planning stage. The scheme needs metering designed in at the right granularity, so that landlord, communal and dwelling energy can be separated. The obligation has to be capable of being secured, normally by condition or through the section 106 agreement. And someone has to own the reporting duty after the contractor leaves, which is a management question the applicant should answer before the council asks.

Write the metering strategy into the statement. A single sentence promising compliance with the reporting requirement, with no metering schematic behind it, is the version that attracts a pre-commencement condition nobody wants.

Offsetting the residual

Whatever carbon remains after the three physical stages is offset by a cash in lieu payment to the borough, calculated over an assumed thirty year period and secured through a planning obligation.

Boroughs set the price they apply and some have moved away from the figure first recommended by the Mayor, so take the rate from the borough's current published schedule rather than from an older scheme's assessment. Get this wrong and the section 106 heads of terms are drafted on a number that changes late in the process, which is exactly when the viability argument is least welcome.

Offsetting is the last resort in the policy, not a purchasing option. A statement that reaches the minimum on-site percentage and buys out the rest without showing why more could not be achieved on site is asking for a challenge.

Assembling the statement for a referable scheme

Set the document out in the order of the hierarchy, with the carbon figures carried through in a single consistent table stage by stage, so a reader can follow one number from the notional baseline to the residual.

Include the modelling outputs as an appendix, name the software and version, and state the weather file used. For referable applications the GLA reviews the assessment directly and will ask for the underlying files, so assume they will be read rather than skimmed.

Coordinate it with the rest of the pack. The Energy Statement, the Whole Life Carbon Assessment and the Sustainability Statement share assumptions about floor areas, systems and lifespans, and the fastest way to lose credibility is to give three different gross internal areas across three documents in the same submission.

This is general guidance, not legal advice. Check the current London Plan guidance and your borough's requirements before relying on it.

PlanScope drafts an Energy Statement structured to the policy framework and flags where the modelling outputs still have to be inserted, which saves the narrative writing rather than the engineering. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.