England has published 2026 editions of Approved Document L (energy and greenhouse-gas emissions) and Approved Document F (ventilation) for dwellings. As of September 26, 2026, the ordinary effective date is March 24, 2027; the stated date for higher-risk building work and work to an existing higher-risk building is September 24, 2027. These dates do not by themselves decide which edition applies to a secondary dwelling or conversion.
Start with scope and project records
The 2026 documents apply to building work in England. The official Building Circular 01/2026 describes transitional treatment for qualifying earlier notices or full-plans applications and sets a separate commencement condition. The later Circular 04/2026 corrects the 2026 documents and confirms the ordinary and higher-risk effective dates. Always use the revised documents from the current official pages.
Approved Document L also contains a new functional requirement for on-site renewable electricity generation when a dwelling or a building containing dwellings is erected. Its output method and project limits are covered in the focused England renewable-electricity guide; this transition guide remains focused on the wider Part L and Part F dates and project records.
For a project, establish:
- Whether the work is in England and whether it is a dwelling project within the relevant volume.
- Whether the work is new, an extension, an alteration, or a conversion, and whether it is connected with a higher-risk building.
- Which building-control notice or application was made and when.
- When the work began and whether the applicable transition’s progress condition is met.
- Which current Part L and Part F provisions, calculations, commissioning, and information duties apply.
Energy and ventilation are connected, separate checks
Approved Document L addresses energy and greenhouse-gas requirements; Approved Document F covers ventilation. They are not one interchangeable checklist. The 2026 England guidance includes new requirements and updated technical guidance, but the circulars do not supply the complete design solution. Use the current Approved Document L, Volume 1 PDF and Approved Document F, Volume 1 PDF, together with the governing regulations and approved methodologies.
Do not presume that every ADU is treated as a new dwelling for each Part L or F provision. A small unit created inside an existing building may have a different classification or work scope from a new detached dwelling. The building-control body should confirm the route, any transition, and whether the project needs professional calculations, testing, commissioning, or owner information.
Do not transfer England’s dates
These dates and documents apply to England only. Wales has separate Part L and F guidance and a March 2027 effective date; Scotland and Northern Ireland have different systems. Use the UK country-route guide and the Wales transition guide for those jurisdictions.
The date and transition information is a current checkpoint, not a compliance result. Ask the responsible English building-control body to confirm the project classification, applicable edition, exact transition provisions, and technical evidence before relying on a design.