This article covers the London Plan 2021, Policy SI 2, as applied by the GLA's Energy Assessment Guidance (June 2022) and its Part L 2021 cover note. A new draft London Plan was published in July 2026 and changes this approach. It isn't adopted yet; see the end of the article.
Who needs a GLA-style energy assessment
The net zero carbon target applies to all major developments, not just those referred to the Mayor. The GLA guidance gives 10 or more homes, or more than 1,000 m² of floorspace, as examples, and points to the Mayor of London Order 2008 for the full definition.
A scheme is referable to the Mayor, and gets GLA energy officer comments at Stage 1 and Stage 2, if it meets the Order's criteria. Those include 150 or more homes, buildings over 30 m high outside the City of London, and development on Green Belt or Metropolitan Open Land.
Boroughs assess the non-referable majors themselves. The GLA encourages them to use the same structure, so most London boroughs expect the same hierarchy, the same spreadsheet and the same targets.
The targets
| Target | Residential | Non-residential | Source |
|---|---|---|---|
| Overall | Net zero carbon (regulated emissions) | Net zero carbon (regulated emissions) | Policy SI 2; EAG 2.1 |
| Minimum on-site reduction beyond Part L 2021 | 35% | 35% | EAG 1.7, 2.2 |
| Benchmark to aim for | 50% or more | None set | EAG Table 1 |
| Be lean (energy efficiency alone) | 10% | 15% | EAG 2.3, 7.1 |
| Shortfall to zero | Offset payment to the borough | Offset payment to the borough | EAG 6.4 |
Two details catch people out:
- Residential and non-residential are tested separately. A mixed-use scheme can't use a strong residential result to carry weak commercial space. Both the 35% and the be lean targets apply to each use on its own.
- The baseline is the Part L 2021 target emission rate (TER) from the final proposed specification. For non-residential buildings, that notional building already includes heat pumps (seasonal efficiency of 2.86 for hot water and a seasonal coefficient of performance of 2.64 for space heating, EAG footnote 20). So a non-residential scheme gets credit only for doing better than those values. The GLA's own cover note accepts that non-residential schemes may find 35% harder to reach for this reason.
The four stages
| Stage | What counts | Practical notes |
|---|---|---|
| Be lean | Fabric, airtightness, thermal bridging, ventilation heat recovery, efficient lighting, passive design (orientation, shading, thermal mass) | Modelled with the notional heating system from the Part L baseline, so the saving reflects demand reduction only. Homes also report the fabric energy efficiency (FEE) result |
| Be clean | Connection to an existing or planned district heat network, local secondary heat sources, a communal network ready to connect | Developments in Heat Network Priority Areas follow the heating hierarchy in Policy SI 3. Heat pumps serving a district network count here |
| Be green | Renewables on site: PV, heat pumps, solar thermal, storage | Heat pumps always count here, not under be lean, unless they serve a district heat network (EAG 10.6) |
| Be seen | Monitoring and reporting energy use after completion through the GLA's platform | Reporting runs through the first five years in use (RIBA Stage 7) |
On top of the carbon figures, the assessment reports energy use intensity (EUI) and space heating demand, and should aim for the values in the guidance:
| Building type | EUI (kWh/m²/year) | Space heating demand (kWh/m²/year) |
|---|---|---|
| Residential | 35 | 15 |
| School | 65 | 15 |
| Office | 55 | 15 |
| Hotel | 55 | 15 |
| All other non-residential | 55 | 15 |
Source: GLA Energy Assessment Guidance 2022, Table 4. EUI excludes any renewable contribution.
The assessment also has to show the cooling hierarchy has been followed and include dynamic overheating modelling (Policy SI 4). For homes, that modelling now has to respect the limits Part O places on window opening and shading.
How the offset payment is worked out
The calculation is simple (EAG 6.4):
- Take the residual regulated emissions after be green, in tonnes of CO₂ a year.
- Multiply by the assumed life of the services, usually 30 years.
- Multiply by the offset price: the GLA recommends £95 a tonne, or the borough's own price.
Example: a scheme left with 20 tonnes a year pays 20 × 30 × £95 = £57,000.
The GLA is clear that the payment isn't an alternative to on-site savings (EAG 6.6). It's accepted only once the applicant has shown no further on-site savings are feasible. Pricing on-site measures against the offset cost won't get through an energy officer's review.
Why energy statements get comments back
From the guidance, these are the points energy officers check first:
- Be lean below 10% (homes) or 15% (non-residential). Usually fabric left at the Part L 2021 notional values, or heat pump savings put in the wrong stage.
- Residential and non-residential results not shown separately.
- No evidence on heat networks. Developments in Heat Network Priority Areas need correspondence with the network operator, and a communal system ready to connect.
- Renewables not maximised. The GLA expects on-site renewables to be maximised (EAG 10.2), so a roof only partly used for PV needs a reason.
- EUI and space heating demand missing from the GLA reporting spreadsheet.
- Overheating modelling missing, or done without allowing for Part O.
- Statement submitted after planning. The guidance says it must come with the application, not as a condition.
Before the energy statement: a checklist
- Confirm whether the scheme is major, and whether it's referable to the Mayor.
- Check the London Heat Map for Heat Network Priority Areas and existing networks nearby.
- Set fabric, airtightness and ventilation to beat the Part L 2021 notional values by enough to clear 10% or 15% on be lean alone.
- Model homes in SAP 10.2 and non-residential space in SBEM or dynamic simulation, using representative dwelling types.
- Decide the heating strategy through the heating hierarchy, and put heat pump savings under be green.
- Size PV to the usable roof, not to the minimum needed.
- Report EUI and space heating demand against Table 4.
- Run dynamic overheating modelling alongside, not after.
- Calculate any offset payment and agree the price with the borough.
- Complete the GLA carbon emissions reporting spreadsheet and submit it in Excel with the statement.
What the draft London Plan 2026 would change
The Mayor published a draft new London Plan in July 2026. Consultation closed on 15 October 2026, and the GLA expects to submit it to the Secretary of State in 2027 for examination. Until it's adopted, the London Plan 2021 and the 2022 guidance remain the policy.
The draft takes a different approach to energy:
- Energy targets instead of carbon targets. Draft Policy GHR1 sets minimum EUI and space heating demand standards. Space heating demand would be 20 kWh/m²/year (baseline) or 15 (aspirational) for all building types. EUI standards are set by building type, for example 40 (baseline) and 35 (aspirational) for homes, and 90 and 70 for offices.
- No carbon offsetting policy. The draft's supporting text refers to "the removal of carbon offsetting policy".
- One set of London-wide standards. Boroughs would not set their own energy efficiency or carbon reduction standards in local plans.
- Low Carbon Heat Appraisal. Draft Policy GHR2 asks every major development to appraise its heating options on cost as well as carbon.
- Monitoring continues for at least five years after occupation.
If your scheme will be decided after the new plan is adopted, or the borough is already giving the draft weight, it's worth checking the EUI and space heating figures now. Ask the borough how it is treating the draft.
More on the service: GLA London Plan energy statements and energy statements for planning.
