The Part L uplift: three targets for a new dwelling
A new dwelling now has to pass three separate targets, not one. Primary energy is the target that catches schemes designed around a gas boiler.
The part l 2021 uplift new dwellings have to meet is the 2021 edition of Approved Document L Volume 1, which took effect for work from 15 June 2022 and raised the carbon standard for a new home by around 31 per cent against the previous edition. A new dwelling now has to pass three separate targets rather than one, and the third of them, primary energy, is the one that catches schemes designed around a gas boiler.
For a planning application the uplift matters in two ways. It changes what counts as policy-compliant in an energy statement, and it changes the arithmetic of any local policy expressed as a percentage improvement over Approved Document L.
The three targets a new dwelling has to meet
Compliance is demonstrated through a SAP calculation for each dwelling, and the calculated performance has to beat three targets at once.
| Target | What it measures | Units |
|---|---|---|
| Target Emission Rate | Regulated carbon dioxide emissions | kg CO2 per m² per year |
| Target Primary Energy Rate | Primary energy demand, including fuel generation and distribution losses | kWh per m² per year |
| Target Fabric Energy Efficiency | Space heating and cooling demand from the fabric alone | kWh per m² per year |
Alongside the three targets sit limiting values for individual elements and minimum standards for building services, so a dwelling cannot pass by trading an unheated conservatory specification against a very efficient heat pump. The limiting fabric values and the notional building specification are tabulated in Approved Document L Volume 1, and you should read the current edition rather than a summary, because the tables are where arguments are settled.
Each target is calculated for the individual dwelling, not averaged across the development. That is the first thing to check in a submitted set of SAP outputs.
What changed in the notional dwelling
The targets are derived from a notional dwelling of the same size and shape as yours, built to a specification set out in the Approved Document. Raising the standard means improving that notional specification, and three changes did most of the work.
The notional fabric improved across walls, roofs, floors, windows and air permeability. Wastewater heat recovery appeared in the notional specification. And photovoltaics were included on the notional house, sized in relation to the ground floor area, which is why a detached house with no renewables now struggles to meet the emission target.
Heating also changed. New wet heating systems in new dwellings are designed to a maximum flow temperature of 55 degrees Celsius, which means larger emitters and pipework sized for low-temperature operation. That requirement costs little at design stage and a great deal to retrofit, and it is the detail most often missing from a developer's standard house type when it first comes forward.
Two further changes sit outside Part L but arrived with it. Approved Document O introduced an overheating requirement for new residential buildings, assessed either by a simplified method or by dynamic thermal modelling, and an Overheating Risk Assessment against CIBSE TM59 is now routinely requested at planning stage in urban areas. Approved Document S introduced electric vehicle charge point provision.
Primary energy alongside carbon
Primary energy counts the energy used at the building plus the losses in generating and delivering it. Electricity carries a larger factor than gas at the meter because of those upstream losses, though the factors used in the calculation methodology reflect a decarbonising grid.
The practical effect is that primary energy and carbon can pull in different directions. A design can meet the emission target through on-site photovoltaics while failing primary energy because the heating system is inefficient, or the reverse. Checking only the carbon figure, which is what most planning energy statements historically reported, no longer demonstrates compliance.
Report all three figures in the energy statement: the dwelling emission rate against target, the dwelling primary energy rate against target, and the dwelling fabric energy efficiency against target. A single percentage improvement figure without the underlying three comparisons tells an officer nothing.
Transitional arrangements and what they covered
The 2021 edition applied to work from 15 June 2022, with a transitional provision for schemes already in the system. Where a building notice, initial notice or full plans had been given or deposited before that date, the previous standards could still apply to an individual building provided work on that building started before 15 June 2023.
Two points are worth holding onto. The transitional test applied building by building rather than site by site, so a large phased development could not shelter later plots behind an early start on plot one. And the transitional window has long closed, so any dwelling now being built is assessed against the 2021 standards regardless of when the planning permission was granted.
Planning permission and Building Regulations approval are separate consents with separate timelines. A permission granted in 2019 does not carry an entitlement to build to a 2019 energy standard.
Where planning policy sits above the regulations
Section 1 of the Planning and Energy Act 2008 allows a local plan to include policies requiring energy efficiency standards that exceed the Building Regulations, and government statements have periodically limited how far councils should go. The position has shifted more than once, so check the current national statement and the adopted local plan policy together before advising a client.
London is the clearest case of policy sitting above the regulations. The London Plan requires major development to be net zero carbon, with a minimum on-site reduction beyond the Building Regulations baseline and a cash-in-lieu offset payment for the shortfall, calculated and secured through the section 106 agreement. The Be Lean, Be Clean, Be Green, Be Seen hierarchy is how the Greater London Authority expects that case to be structured, and the Be Seen stage requires reporting of as-built performance.
Outside London the pattern varies. Some adopted plans require a percentage improvement over Part L, some require a fabric standard expressed in kWh per m² per year, and some require renewable generation as a proportion of demand. Read the policy wording carefully, because an improvement expressed against "Part L" needs an edition to be meaningful.
What a planning energy statement should carry
An Energy Statement submitted with an application should contain the baseline, the measures and the outcome, in that order, with the arithmetic visible.
What officers look for: the SAP version used, the three target comparisons for each dwelling type, the fabric specification as a schedule of U-values and air permeability, the heating and hot water strategy with flow temperature, the renewable generation with array area and orientation, the overheating position, and a statement of how the design meets the relevant local policy. Where a shortfall remains, state the offset payment calculation.
Where the scheme is commercial as well as residential, the non-domestic volume of the Approved Document applies to those parts and the modelling method differs, which is covered in energy statements for warehouse and logistics schemes.
Roof area is usually the constraint on renewables, and it is also wanted for drainage attenuation and biodiversity. Resolving that competition early is easier than redesigning at reserved matters, and the combinations that work are set out in biosolar roofs: energy, drainage and biodiversity together.
The Future Homes Standard is intended to raise the standard again. Check the current position and any transitional dates on gov.uk before relying on a programme assumption, because the detail and the timing have both moved.
Errors that show up in submitted SAP outputs
The same handful of mistakes appear in planning submissions again and again.
- Reporting only the carbon figure and omitting primary energy and fabric energy efficiency.
- Using a default thermal bridging value rather than calculated junction details, which flatters the fabric result and is then not achievable on site.
- Assuming an air permeability well below the value the contractor will actually test to.
- Modelling photovoltaic arrays with no shading and an ideal orientation that the roof plan does not support.
- Averaging results across house types instead of reporting the worst case.
- Omitting the 55 degree flow temperature requirement from the heating specification.
- Submitting a design stage calculation and never reconciling it with the as-built report and its photographic evidence requirement.
That last one is becoming the pinch point. The as-built Part L report requires photographic evidence of insulation and airtightness detailing, and a design that was never buildable shows up at that stage rather than at planning.
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Frequently asked questions
What are the three Part L targets for a new dwelling?
The Target Emission Rate in kilograms of carbon dioxide per square metre per year, the Target Primary Energy Rate in kilowatt hours per square metre per year, and the Target Fabric Energy Efficiency in kilowatt hours per square metre per year. All three must be met by each individual dwelling, alongside limiting values for fabric elements and minimum standards for building services.
When did the Part L uplift take effect?
The 2021 edition of Approved Document L applied to work from 15 June 2022. A transitional provision allowed the previous standards to apply where a building notice, initial notice or full plans had been given or deposited before that date and work on that individual building started before 15 June 2023. That window has closed.
Why does primary energy matter if my scheme meets the carbon target?
Because compliance requires all three targets. Primary energy counts the energy used in the dwelling plus the losses in generating and delivering it, so an inefficient heating system can fail primary energy even where on-site renewables bring the carbon figure under target. Reporting only the carbon result no longer demonstrates compliance.
Can a council require better than Part L through its local plan?
Section 1 of the Planning and Energy Act 2008 allows local plan policies on energy efficiency, and national statements have periodically limited how far those policies should go. The position has shifted more than once, so check the current national statement alongside the adopted local plan policy, and note that London operates its own net zero carbon regime.
What is the 55 degree flow temperature requirement?
New wet heating systems in new dwellings are designed to a maximum flow temperature of 55 degrees Celsius, which requires larger emitters and appropriately sized pipework. It costs little at design stage and a great deal to retrofit, and it is the detail most often missing from a standard house type when it first comes forward for planning.
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.