UK Building Regulations & Sustainability

Where regulation is heading

UK building regulations are evolving rapidly in response to the climate emergency. For decades, sustainability in regulation meant one thing: operational energy efficiency (Part L). That is now expanding to include embodied carbon, whole life carbon, and broader environmental performance.

Understanding the regulatory direction helps you make material choices today that will still comply tomorrow. It also helps you advise clients on future-proofing their projects against tightening requirements.

This guide covers the current regulations, confirmed upcoming changes, and probable future requirements relevant to sustainable material specification in England and Wales. Scotland and Northern Ireland have their own building standards with broadly similar trajectories.

Part L: Conservation of fuel and power

Part L is the primary regulation governing energy efficiency in buildings. It sets requirements for insulation levels (U-values), airtightness, heating system efficiency, and overall energy performance. It has been progressively tightened through successive editions.

The 2021 update to Part L (effective June 2022) introduced a significant step change, requiring approximately 30% lower CO2 emissions from new homes compared to the previous edition. Key changes included:

Fabric-first approach

Prioritises insulation, airtightness, and thermal bridging reduction.

Energy & CO₂ targets

Primary energy rate and CO₂ emission rate must meet or beat notional building.

Overheating assessment

CIBSE TM59 methodology required for new residential buildings.

No new fossil fuels (2025)

From 2025, no gas boilers in new homes under the Future Homes Standard.

Note. Part L drives insulation specification, airtightness detailing, and window performance. Higher insulation requirements mean more insulation material per building - making the embodied carbon of that insulation material increasingly relevant.

The Future Homes Standard (2025)

The Future Homes Standard (FHS) is a major regulatory update that will apply to new homes in England from 2025. It represents the government's pathway to ensuring all new homes are 'zero carbon ready' - designed so that no further retrofit is needed to achieve zero operational carbon as the electricity grid decarbonises.

75–80% CO₂ reduction

Compared to Part L 2013 baseline. A major step change in performance.

No gas boilers

Heat pumps or district heating required. End of gas in new homes.

Enhanced airtightness

Tighter envelopes with improved ventilation strategies.

Whole-building testing

Performance gap between design and as-built must be closed.

Watch out. The Future Homes Standard focuses on operational carbon, not embodied carbon. A home could comply fully with FHS while using high-embodied-carbon materials. This gap is what Part Z aims to address.

Part Z: The push for embodied carbon regulation

Part Z is a proposed amendment to the Building Regulations that would introduce mandatory whole life carbon assessment and embodied carbon limits for new buildings. It is not yet law, but it represents the direction of travel and is supported by a broad coalition of industry bodies.

The Part Z proposal, developed by a cross-industry group including engineers, architects, and professional bodies, would require:

Topic	Detail
Whole life carbon assessment	mandatory calculation of embodied carbon (A1-A5 and C) plus operational carbon (B6-B7) for all new buildings above a minimum size threshold. This would use EN 15804-aligned methodology.
Embodied carbon limits	maximum kg CO2e per m2 of floor area for new buildings, differentiated by building type. The limits would tighten over time on a published trajectory, giving the industry certainty to invest in low-carbon manufacturing.
Upfront carbon reporting	disclosure of A1-A5 embodied carbon at planning stage, enabling local authorities to factor carbon into planning decisions.
Material-level benchmarks	carbon intensity targets for key materials (concrete, steel, insulation) based on current best practice, creating a floor below which the worst performers cannot operate.

Note. Part Z is not yet enacted, but the Greater London Authority already requires Whole Life Carbon assessments for referable planning applications. Several other local authorities are following suit. The trajectory is clear even if the national timeline is uncertain.

BREEAM and sustainability rating schemes

While building regulations set minimum legal requirements, voluntary rating schemes like BREEAM set higher benchmarks that many clients and planning authorities require. Understanding how they interact with regulations helps you advise on material specification.

Topic	Detail
BREEAM (Building Research Establishment Environmental Assessment Method)	the UK's most widely used sustainability rating scheme. Material credits (Mat 01) require EPD data and reward responsible sourcing (BES 6001, FSC/PEFC). Higher BREEAM ratings increasingly require whole life carbon assessment.
LETI (London Energy Transformation Initiative)	publishes design guidance and carbon benchmarks for new buildings. LETI targets are more ambitious than current regulations and are increasingly referenced in planning policy. Their embodied carbon targets (e.g. <500 kg CO2e/m2 for residential) are a useful yardstick.
RIBA 2030 Climate Challenge	sets progressive targets for operational energy, embodied carbon, and potable water use aligned with the Paris Agreement. Provides a framework for practices to track their progress.
NABERS UK	a performance-based rating system for operational energy in commercial buildings. Focuses on actual measured energy use rather than design predictions. Relevant because it shifts focus to real outcomes.
Passivhaus / EnerPHit	energy performance standards with strict fabric-first requirements. Not a UK regulation but widely adopted and increasingly referenced in local planning policy. Demands very high insulation levels and airtightness.

What this means for material specification

The regulatory direction creates clear implications for how materials should be specified today, even before all regulations are enacted.

Topic	Detail
Insulation performance will keep tightening	specify materials that can achieve very low U-values in practical build-ups. Consider thermal bridging at junctions, not just clear-wall performance.
Embodied carbon data will become mandatory	choose suppliers who already provide EPD data. Products without EPDs will become harder to specify as reporting requirements increase.
Whole life thinking is coming	material durability, replacement cycles, and end-of-life pathways will all matter for compliance. A cheap material that needs replacing twice has three times the reporting burden.
Responsible sourcing will be a baseline expectation	BES 6001, FSC/PEFC, and similar certifications will move from 'nice to have' to 'expected' as BREEAM requirements tighten and Part Z-style regulations emerge.
Local planning may lead national regulation	if your projects are in London or other progressive authorities, expect whole life carbon requirements now, regardless of national regulation timelines.
Specify for the next standard, not the current one	buildings designed today will be occupied for 60+ years. Designing to current minimum standards risks obsolescence. Designing to LETI or FHS standards future-proofs the building and the specification.

Tip. Use Matera to find suppliers with EPD-verified products, BES 6001 certification, and transparent carbon data. Having this information ready makes compliance with current and future requirements straightforward.

Key resources and links

These organisations publish the guidance and standards referenced in this guide. Bookmark them for the latest updates on regulatory changes.

Topic	Detail
HM Government	Building Regulations Approved Documents (planning portal)
LETI	Climate Emergency Design Guide and embodied carbon targets
UKGBC	Net Zero Carbon Buildings Framework and whole life carbon guidance
BRE	BREEAM scheme documents and technical standards
Part Z campaign	proposed regulatory text and supporting evidence
RIBA	2030 Climate Challenge targets and practice guidance
Passivhaus Trust	UK-specific guidance on Passivhaus and EnerPHit standards