Be Lean, Be Clean, Be Green, Be Seen in a London energy statement
An energy statement for a London scheme has to work through the hierarchy in sequence, with separate modelling at each stage and a monitoring commitment that outlives the application.
The London Plan energy hierarchy statement has to work through four stages in order, and the order is the policy. Policy SI 2 of the London Plan asks major development to be net zero-carbon, with a minimum on-site reduction in regulated emissions beyond the Building Regulations baseline, a stated minimum of that reduction achieved through energy efficiency alone, and any residual emissions offset through a cash in lieu payment to the borough's carbon offset fund. Then the building has to report what it actually does once it is built.
Assessors who run all four stages simultaneously and present a single percentage will be asked to resubmit. The Greater London Authority reads the stages sequentially because the policy is sequential.
What each stage asks for
- Be Lean: use less energy, through fabric performance, form factor, glazing ratio, airtightness, thermal bridging and the avoidance of active cooling.
- Be Clean: supply energy efficiently, principally by connecting to an existing or planned heat network where one is available.
- Be Green: use renewable energy, in practice photovoltaics on almost every scheme and heat pumps where they are not already counted at the Be Clean stage.
- Be Seen: monitor and report actual energy performance after completion, through the Mayor's reporting portal.
The adopted policy sets the on-site reduction at 35 per cent beyond the Building Regulations target emission rate, with at least 10 per cent of that achieved through energy efficiency measures on residential schemes and at least 15 per cent on non-residential ones. The baseline edition against which those percentages are calculated is set by the Mayor's energy assessment guidance rather than by the Plan itself, and that guidance has been updated since adoption. Check the current version before you fix a baseline, because an assessment run against the wrong edition of the Building Regulations is the most common reason a statement is returned unread.
Evidence at the Be Lean stage
This stage is where the design work shows or does not show. The GLA wants to see that efficiency was pursued before technology was bolted on.
Report the fabric parameters as built into the model: U-values for each element, the glazing ratio by elevation, the air permeability target, the approach to thermal bridging with psi values rather than default accredited construction details where you can manage it, and the ventilation strategy. State the form factor. A compact block with a form factor near 1.5 will pass on fabric in a way that a set of detached villas at 3.0 will not, and saying so honestly is better than presenting an implausible U-value schedule.
Two failures recur. Specifying fabric that the cost plan will not carry, which surfaces at the as-built reporting stage and leaves the applicant exposed. And claiming efficiency savings from a measure that belongs at a later stage, such as counting a heat pump's efficiency as a Be Lean saving. The second gets picked up almost every time.
Where the scheme involves an existing building, the fabric case interacts with heritage constraints, and the insulation options narrow sharply on a listed or locally listed elevation.
Heat network connection and the Be Clean test
The policy hierarchy expects connection to an existing district heating network where one is within reach, then connection to a planned network, then a site-wide network for the development itself.
Prove the position rather than asserting it. That means a map showing the nearest existing and planned networks with distances, correspondence with the operator, and the reason a connection is not viable where you are not proposing one. A statement that "no network is available" without evidence of the enquiry will be queried.
Where a connection is not available now but a network is planned, the standard response is to design the scheme so that it can connect later. That means a single plant room location, space for a heat exchanger, and a distribution arrangement that does not need to be rebuilt. Where a phased site is involved, the sequencing question is larger than one plot and is covered in energy masterplanning across a phased site.
The gas question now sits inside this stage. A combined heat and power engine that would once have earned a reduction against a gas baseline no longer does the same work on a decarbonising grid, and most London schemes are now all-electric. The decision and its consequences are set out in all-electric new homes and the gas connection decision.
Renewables and the Be Green stage
Photovoltaics carry this stage on most schemes. Report the array area, orientation, tilt, the assumed yield and the basis of that assumption, and show the array on a roof plan alongside everything else competing for the same roof.
That competition is real. Plant, lift overruns, terraces, green roofs, drainage attenuation and maintenance access all want the same surface. A combined arrangement is usually the answer, and the technical detail sits in biosolar roofs, combining panels and green roof.
Air source heat pumps deliver carbon savings at this stage where they were not already counted at Be Clean. Two design consequences follow. External units need space, acoustic separation from bedrooms and neighbouring windows, and a maintenance route. And the overheating assessment needs to be run on the same model, because a scheme optimised for winter heat demand can fail an overheating check. The overheating risk assessment should not be produced by a different consultant working from different assumptions.
Be Seen monitoring and reporting
This is the stage most applicants underestimate, because it creates obligations that outlive the planning application.
Reporting happens at three points: as designed at the planning stage, as built at completion, and in use once the building is operating and metered data exists. The data goes to the Mayor's reporting portal, and the obligation is normally secured by planning condition or by a section 106 obligation.
Two practical consequences. The metering strategy has to be designed in, with sub-metering by end use and by tenure where the building is mixed, because you cannot report what you did not meter. And somebody has to own the reporting duty for years after the contractor has left, which means naming the responsible party in the management arrangements rather than leaving it with a demolished project team.
Where schemes fail the hierarchy in order
The commonest failure is arithmetic presented out of sequence. The assessment reports a total reduction, then works backwards to allocate it across the stages. The GLA will ask for the stage-by-stage outputs with the modelling runs behind each one.
Second is an efficiency shortfall covered by renewables. If the residential scheme achieves 6 per cent through fabric and then adds panels to reach the overall figure, it fails the minimum efficiency element even though the total looks acceptable.
Third is an offset payment treated as the plan rather than the residue. Offsetting is available for what remains after the on-site measures, and a scheme that proposes to buy its way past the on-site minimum is not compliant.
Fourth, and this one is quiet, is a whole life carbon position that contradicts the energy statement. A heavily serviced building with a low operational figure and a very high embodied figure invites a question the energy statement alone cannot answer, which is why the whole life carbon assessment should be drafted alongside it rather than afterwards.
Assembling the statement for a referable scheme
For a scheme referable to the Mayor, which includes residential development of 150 units or more, the energy statement will be read by GLA officers as well as by the borough. Structure it so that each stage has its own section, its own modelling output and its own percentage, with a single summary table at the front carrying the regulated emissions at each stage in tonnes of carbon dioxide per year and the cumulative percentage reduction.
Include the modelling software and version, the weather file used, the baseline edition, the treatment of unregulated emissions, the offset calculation with the borough's current price per tonne, and the proposed monitoring commitment. Where a figure depends on a decision not yet made, say so rather than inserting a placeholder.
An energy statement drafted this way gives the case officer something they can lift into a report. One that presents a single number does not.
This is general guidance rather than legal advice. Check the position with your local planning authority or a qualified professional 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.
Frequently asked questions
What on-site reduction does London Plan Policy SI 2 require?
The adopted policy asks for a minimum 35 per cent reduction in regulated carbon emissions beyond the Building Regulations target, with at least 10 per cent achieved through energy efficiency on residential schemes and at least 15 per cent on non-residential schemes. The baseline edition used for that calculation is set by the Mayor's energy assessment guidance.
Can I offset the whole carbon shortfall with a payment?
No. The cash in lieu contribution to the borough carbon offset fund covers residual emissions after the on-site measures have been applied. A scheme that proposes to pay its way past the minimum on-site reduction or past the minimum efficiency element does not comply with the policy, however large the payment.
What does the Be Seen stage actually require?
Reporting of energy performance at three points: as designed at application stage, as built at completion, and in use once metered data exists. Data goes to the Mayor's reporting portal and the duty is usually secured by condition or planning obligation. It needs a metering strategy designed in and a named party responsible after handover.
Does a heat pump count at the Be Clean or Be Green stage?
It depends how it is used. Where a heat pump forms the site heat supply it is normally reported at the Be Clean stage. Where it is added as a renewable technology after the supply strategy is set, it counts at Be Green. What it cannot do is count as a Be Lean efficiency saving, which is a common and easily spotted error.
Which schemes are referable to the Mayor?
Referral thresholds are set by the Mayor of London Order and include residential development of 150 units or more, along with tall buildings and larger floorspace proposals meeting stated criteria. Referable schemes have their energy statement reviewed by Greater London Authority officers as well as by the borough case officer.
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.