England has set a new default for clean power in housing. On 23 March 2026 ministers signed the Building Regulations etc. (Amendment) (England) Regulations 2026, implementing the Future Homes and Buildings Standards. Part L is retitled “Energy and greenhouse gas emissions” and, from 24 March 2027, a new requirement L3 mandates on‑site renewable electricity for new homes and buildings containing dwellings. For higher‑risk buildings (HRBs), related provisions start on 24 September 2027.

What L3 means on the ground is simple: when a dwelling (or a building that contains dwellings) is erected, a system that generates renewable electricity must be installed on the building or within its plot. Power must be available to residents and the system must deliver a ‘reasonable output’ for the site’s design and surroundings. Exemptions exist for specified ‘relevant buildings’, for plots where on‑site output would be unreasonable, and where an equivalent output is delivered from a shared renewables system that supplies residents.

The update also changes how compliance is judged. Requirement L1 now refers explicitly to minimising greenhouse gas emissions as well as conserving fuel and power. The definition of ‘fixed building services’ is widened to include lifts, escalators and moving walkways in new buildings, and a new Regulation 40C requires handover information for new-home owners to be provided in an appropriate, accessible format. Commissioning and airtightness references are aligned to the revised L1 numbering.

The direction aligns with the government’s Future Homes and Buildings Standards programme to deliver ‘zero‑carbon ready’ buildings. Officials have already signalled that the vast majority of new homes will include solar under the standard to cut bills as electricity prices fluctuate. (gov.uk)

Why it matters: buildings produced about 17% of UK greenhouse gas emissions in 2023. Moving Part L from an energy‑only lens to one that also targets emissions links building control directly to the UK’s carbon budgets. (gov.uk)

Timings are clear. Most provisions take effect on 24 March 2027, with transitional relief where a building notice, initial notice or an application with full plans is submitted before that date and work starts before 24 March 2028. For HRBs, changes apply from 24 September 2027 with similar application‑based transitions. For design teams, that creates a one‑year window to lock in roof layouts, inverter positions, wiring routes and updated handover packs.

For residents, the benefits are tangible. Energy Saving Trust notes a typical 3.5 kWp home solar system in the UK and estimates such systems can save around one tonne of CO2 a year, depending on location and use; government messaging adds that households can save hundreds of pounds annually where solar is fitted. Real‑world savings depend on tariffs and daytime consumption. (energysavingtrust.org.uk)

Supply chains look ready. The Microgeneration Certification Scheme reports record volumes of small‑scale renewables in 2025, signalling strong installer capacity ahead of the 2027 start date-important for housing associations and SME builders planning multi‑plot schemes. (mcscertified.com)

For apartment blocks and mixed‑use schemes, the broader definition of ‘fixed building services’ brings lifts and moving walkways into Part L’s energy and emissions frame. Communal rooftop arrays that supply multiple dwellings can meet L3 where electricity is available to residents; early coordination on roof space, metering and fire‑safety guidance is essential. (gov.uk)

Practical next steps for builders: size PV arrays for ‘reasonable output’ using site‑specific shading and orientation studies; integrate cable routes and inverter locations at RIBA Stage 2; specify high‑efficiency heat pumps and controls to meet the strengthened L1; prepare digital handover packs that satisfy Regulation 40C, including plain‑English guides to smart meters, time‑of‑use tariffs and basic maintenance. The government’s indication that most new homes will have solar should be treated as the starting point, not the ceiling. (gov.uk)

Policy plumbing is moving too. Government plans to reform Energy Performance Certificates and introduce smarter metrics are designed to help people understand and manage building performance-useful context for how Part L’s new emissions focus will be communicated to buyers and tenants. (gov.uk)

What to watch for in 2026–27: updated Approved Document L guidance and the Home Energy Model that will sit behind compliance assessments. With emissions now explicit in Part L, England has a route to lower bills and cleaner power-provided delivery teams use the next year to fix designs, line up installers and embed effective resident handover. (assets.publishing.service.gov.uk)