This guide records the position reviewed on 25 July 2026. Projects must still confirm the applicable regulatory edition and transitional route building by building.
Government published the Future Homes and Buildings Standards package and Approved Document L in March 2026. Publication does not mean every current project moves immediately to the new guidance. Effective dates, building-control submissions, commencement and higher-risk-building rules all matter.
The main effective dates
The 2026 regulations and Approved Document L take effect on 24 March 2027 for work that is not higher-risk-building work. Relevant provisions for higher-risk-building work and work to an existing higher-risk building take effect on 24 September 2027.
These are not the only dates a project team needs. Transitional provisions refer to the timing and validity of building notices, initial notices or applications, and to commencement. Higher-risk buildings have a separate approval and transition framework.
Non-HRB transition is building by building
The government's Building Circular states that, for non-HRB work, the changes do not apply to a building where a valid building notice, initial notice or full-plans building-control approval application was given before 24 March 2027, provided the relevant work on that building commences before 24 March 2028.
A site-wide planning permission or a start elsewhere on a development is not a safe substitute for checking the Building Regulations definition and the position of each building. The project team should record its building-control and commencement evidence.
SAP 10.3 is the initial methodology
Government updated its approved domestic methodology from SAP 10.2 to SAP 10.3 in March 2026. The current GOV.UK SAP guidance, updated on 8 June 2026, states that SAP 10.3 is currently the sole approved methodology following a delay to the Home Energy Model.
Approved software and the applicable regulatory route still control what can be used for a specific submission. Do not rename an older calculation or assume that a design automatically complies with the 2026 standard because it has been run in newer software.
HEM follows later
The Home Energy Model is intended to replace SAP for the energy rating of dwellings. It did not launch at the same time as the Future Homes Standard. Government says it will be introduced alongside SAP 10.3 later, after further assurance and readiness work.
No speculative HEM launch date is stated here. Teams should follow the official SAP guidance and methodology notices rather than programme a project around an unofficial date.
What housebuilders should do now
First, map each phase and building to its intended Building Regulations route and evidence the dates on which transition relies. Second, test the 2026 design implications early enough to influence house types, fabric, systems, plots and procurement.
Third, keep methodology, software version and approved-document edition visible in every modelling brief. Finally, allow for coordination across Part L, Part F, Part O, services design and construction evidence rather than treating the methodology update as a software-only change.
Record the project route
Capture building type, HRB status, building-control submission, approval status and commencement evidence for each relevant building.
Read the 2026 guidance
Compare current types and systems with the published Approved Documents before the effective date.
Confirm software and methodology
Use approved implementations and state the version in the brief and report.
Watch primary sources
Recheck GOV.UK guidance before submission, particularly for HEM and transition updates.
Frequently asked questions
Did the 2026 Approved Document L take effect when it was published?
No. Its stated effective date is 24 March 2027 for non-HRB work, with relevant HRB provisions effective from 24 September 2027, subject to transitional arrangements.
Has HEM replaced SAP?
Not as at this guide's review date. Government states SAP 10.3 is currently the sole approved methodology and HEM will follow later.
Can a whole development use one transition decision?
Do not assume so. The non-HRB transition described by government is building by building, and HRB work has separate arrangements.