Guidance updated for Part L 2021 and Part O 2021

The Greater London Authority published updated Energy Assessment Guidance in June 2022, covering how to prepare an energy assessment to accompany strategic planning applications referred to the Mayor of London¹. The document states that it explains how London Plan policies apply now that Part L 2021 has taken effect, and introduces a percentage improvement benchmark for residential developments together with a requirement to report Energy Use Intensity and space heating demand¹.

The guidance sets a net zero-carbon target for all major developments, defined as those with 10 or more units and those with more than 1,000 square metres of floorspace, not only those referred to the Mayor¹. Applications must demonstrate at least a 35 per cent on-site carbon reduction beyond Part L 2021, met separately for residential and non-residential elements, with any shortfall made up through a payment into the relevant borough's carbon offset fund¹. The offset price assumed is £95 per tonne of carbon dioxide over a period of 30 years¹. Energy efficiency measures alone are expected to reduce regulated CO2 emissions by 10 per cent below a development compliant with Part L 2021 for residential uses, and by 15 per cent for non-residential uses¹.

The guidance also sets out benchmarks for residential developments, which it says are expected to exceed the minimum:

The document confirms that applicants should continue to report dynamic overheating modelling as part of the energy strategy, using Chartered Institution of Building Services Engineers guidance and accounting for the limits Part O 2021 places on choices when undertaking a CIBSE assessment¹. On heating infrastructure, it requires that heat networks should not exceed the CO2 and primary energy factor limits set out in Part L 2021, and that any expansion of a network's capacity should come from a low carbon heat source¹. Heat network operators are now expected to publish a summary of their decarbonisation strategy¹.

The guidance describes the energy hierarchy that major developments are expected to follow:

"be lean: use less energy and manage demand during operation through fabric and servicing improvements and the incorporation of flexibility measures"

It adds that assessments should be submitted at the planning application stage, not post planning in response to a condition, and that all outline planning applications should be accompanied by an energy strategy while full and reserved matters applications must provide a detailed energy assessment¹. A cash in lieu contribution will be considered acceptable only where it has been clearly demonstrated that no further savings can feasibly be achieved on-site¹.

Why it matters for households

The guidance applies to planning applications rather than to existing homes, so it does not change the rules for a householder upgrading a boiler or adding insulation. Its practical effect is on the fabric and servicing of new homes in London, and on the information a developer must supply before permission is granted. The reporting requirements mean that a development's predicted energy use intensity and space heating demand are stated at application stage, and the "be seen" stage of the hierarchy requires monitoring and reporting of actual performance after construction¹. For homes connected to or planned for connection to a district heating network, the requirement that networks stay within Part L 2021 CO2 and primary energy factor limits, and that capacity expansion use a low carbon heat source, bears on the carbon intensity of the heat supplied. The guidance does not set out how offset payments are spent locally, and no detail on that has been reported.

What happens next

The guidance states that the benchmarks may be updated periodically to include additional building types and to reflect improvements in performance over time¹. No further dates are given in the document.

Sources1 cited

1. Date, london.gov.uk