SAP and SBEM outputs a planning officer will ask for

When a planning officer asks for SAP SBEM outputs planning submissions rarely arrive with the right documents attached. The energy statement comes with a summary table typed by the consultant, and the officer wants the calculation output itself: the design stage report generated by the software, with the assessor's reference on it, showing the target and the achieved figures side by side.

Two methodologies, two output documents. SAP for dwellings, SBEM or an approved dynamic simulation model for everything else. Knowing which applies, and which pages of it to submit, avoids a request for further information in week five.

SAP and SBEM, and when each applies

The Standard Assessment Procedure is the approved methodology for dwellings, including new houses and flats and conversions creating dwellings. Its outputs are dwelling specific, so a scheme of 60 homes across eight house types produces eight calculations rather than one.

The Simplified Building Energy Model covers non-domestic buildings and is part of the national calculation methodology. Where a building's form or servicing strategy falls outside what the simplified model handles well, an approved dynamic simulation model is used instead, and the outputs look different.

Mixed use schemes need both. A block with ground floor commercial space and flats above produces SAP calculations for the dwellings and an SBEM or dynamic model output for the commercial shell, and the emissions from the two are reported separately before being combined. Officers frequently receive only one half.

Under Part L 2021 the dwelling metrics are a primary energy rate, an emission rate and a fabric energy efficiency rate, each compared against a target derived from a notional dwelling. Non-domestic buildings are assessed against a target emission rate and a primary energy target. The names of the metrics matter, because a statement quoting only a percentage improvement over an unspecified baseline tells the officer nothing.

Which documents to submit, and when

For a planning submission, a sample is usually acceptable: one output per dwelling type, with the worst case type identified and the reasoning stated. Say in the Energy Statement how many plots each sampled type represents, because an officer cannot check the arithmetic otherwise.

Where a scheme is referable to a strategic authority, or the local plan sets its own carbon reduction target, expect the hierarchy to be reported stage by stage: the lean measures, then the clean measures, then the renewable contribution. Each stage needs its own calculation output, and the difference between them is the number the policy tests.

Reading a design stage report for errors

Officers rarely interrogate these documents. The consultant reviewing on the council's behalf does, and so should you before submission. The recurring errors:

• The dwelling type in the output does not match the drawing. Wrong floor area, wrong number of storeys, a flat modelled as mid floor when it is top floor.
• Orientation not set, or set to a default. This changes solar gains and, on a scheme with a strong east to west axis, changes the result materially.
• Fabric values better than the specification. A wall U-value in the calculation that the drawn construction cannot achieve.
• Air permeability in the calculation better than the figure in the specification, or better than the contractor has agreed to test to.
• Thermal bridging taken as an accredited details value where no accredited details are specified, rather than the default.
• Photovoltaic capacity that does not fit on the available roof once shading, access, plant and any green roof are accounted for.
• Heating system not the one in the mechanical specification. A heat pump in the calculation and a boiler in the drawings is a surprisingly common mismatch, and the decision behind it is discussed in our note on the all-electric new homes and gas connection decision.
• Overheating not assessed at all, which is a separate requirement and not answered by the energy calculation.

Check the assessor's reference, the software version and the date on every output. An undated output with no reference is not evidence of anything.

Assumptions an officer will question

Three, reliably.

Renewable capacity. If the calculation relies on a photovoltaic array, the officer will look for it on the roof plan. An array shown on the calculation and absent from the drawings is the single most common reason an energy statement is sent back.

Communal systems. Where a heat network or communal plant is assumed, the officer will ask where the energy centre is, how it is accessed, and whether the flue and ventilation are shown. On a phased site the network's staging matters, as set out in our note on energy masterplanning across a phased site.

Offsetting. Where a policy requires any residual emissions to be offset through a payment, the calculation has to produce the residual figure in the units the policy uses, over the period the policy specifies. Get the units right or the payment will be recalculated.

Reconciling outputs with the written statement

This is a document control problem more than a technical one. The statement and the outputs have to agree, and on a scheme that has been through three design revisions they usually do not.

A short reconciliation table at the front of the energy statement solves it: dwelling type, plot numbers, output reference and date, target figure, achieved figure, percentage improvement. Every number in the body of the statement should be traceable to a row in that table.

Then check the statement against the drawings and the specification as well as against the outputs. The chain is drawing, specification, calculation, statement, and a break anywhere in it produces a condition requiring the whole thing to be resubmitted.

Where a whole life carbon assessment is also required, its boundary and its assumptions have to match the energy strategy rather than describe a different building, and the interaction is covered on our Whole Life Carbon Assessment page.

Version control across design revisions

Four rules that survive a live project:

1. One output set per design revision, named with the revision and the date, and never overwritten.
2. The revision of the drawings and specification the calculation was run against, recorded on the front of the output set.
3. A single owner of the energy model, with changes requested through them rather than made in parallel copies.
4. A change log listing what moved between revisions and what it did to the result.

The failure mode is familiar. The architect reduces the glazing on the south elevation, nobody tells the energy assessor, and the submitted calculation describes a building that no longer exists. If the discrepancy is found by the council, the fix is a further submission. If it is found at building control, the fix is a design change on site.

Conditions requiring as-built outputs

Most authorities now condition the as-built evidence. Typical wording requires the submission, before first occupation of each dwelling or phase, of as-built calculation outputs and air pressure test certificates demonstrating that the approved performance has been achieved.

Two things to watch when the wording is drafted. Whether the condition requires the design figure to be matched exactly, which will be breached on some plots, or allows a stated tolerance. And whether the trigger is occupation of each dwelling or of each phase, because the administrative difference across 200 plots is considerable.

Ask for a phase based trigger and a tolerance, at the resolution to grant stage. Both are usually agreed if raised then, and neither is easy to change afterwards.

If you are drafting the energy and sustainability documents for a scheme, enter your postcode on PlanScope to see which reports the site is likely to need.

This is general guidance, not legal advice. Calculation methodologies and Approved Documents change, so check the current versions and take advice from a qualified energy assessor before relying on any figure. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.