What Is the Future Buildings Standard?

The Future Buildings Standard (FBS) is the 2026 update to Part L Volume 2 of the Building Regulations for England, covering the conservation of fuel and power in non-domestic buildings. Published on 24 March 2026, the FBS raises energy performance requirements substantially, introducing mandatory solar PV, low-carbon heating, and tighter fabric standards for new non-domestic buildings (AD L2 2026).

Why the FBS matters

The Future Buildings Standard represents the most significant change to non-domestic building energy regulations since Part L was first introduced. It forms part of the government's pathway to achieving net zero carbon emissions by 2050, and sits alongside the Future Homes Standard (which covers domestic buildings).

The standard is designed to ensure that new non-domestic buildings built from 2027 onwards are highly energy-efficient and produce significantly lower carbon emissions than those built under the current Part L 2021 requirements.

Who is affected?

The FBS applies to anyone involved in the design, construction, or commissioning of new non-domestic buildings in England, including:

• Architects and building designers
• Developers and contractors
• SBEM and energy assessors
• Building control bodies
• Mechanical and electrical engineers
• Building owners commissioning new developments

When does it take effect?

The FBS takes effect in two phases (Building Circular 01/2026):

• March 2027 – enforcement for all non-domestic buildings except higher-risk buildings
• September 2027 – enforcement for higher-risk buildings

Projects that have submitted a building control application before the enforcement date may use transitional provisions, provided work commences within 12 months. See the full timeline for key dates from 2019 to 2028.

What's new under the FBS?

Mandatory solar PV

New non-domestic buildings must provide solar PV equivalent to 40% of the building foundation area, for both side-lit and top-lit buildings (consultation response, para 3.11, p18). The current NCM 2021 Equation 9 uses a weighted formula (20% side-lit / 40% top-lit) - this will be updated when the 2026 NCM is published. If 100% of heating is from heat pumps, no PV is required (NCM 2021, para 83). Exemptions also apply for higher-risk buildings.

Low-carbon heating

The notional building specification assumes low-carbon heating systems such as heat pumps. Buildings using fossil fuel heating will struggle to meet the Target Emission Rate (TER) and Target Primary Energy Rate (TPER).

Tighter fabric standards

The notional building specifies improved U-values for walls, roofs, floors, and windows compared to the Part L 2021 notional specification. While most backstop (limiting) values remain unchanged, the tighter notional specification means the overall compliance bar is significantly higher.

Improved lighting efficacy

The FBS requires general lighting efficacy of at least 105 luminaire lumens per circuit watt (lm/W), up from previous standards (AD L2 2026).

How is compliance demonstrated?

Compliance with the FBS is demonstrated through SBEM (Simplified Building Energy Model) or approved Dynamic Simulation Modelling software. The actual building's BER must not exceed the TER, and the BPER must not exceed the TPER – both derived from the notional building specification.

The output is a BRUKL report – the formal compliance document required at both design stage and as-built.

FBS vs FHS

The Future Buildings Standard covers non-domestic buildings, while the Future Homes Standard covers domestic buildings. They were published together but have different calculation methodologies: the FBS uses SBEM/NCM, while the FHS uses the Home Energy Model (HEM). See the full FBS vs FHS comparison.