FBS Consultation Response Summary

The Future Buildings Standard consultation response was published on 24 March 2026 alongside the new Approved Document L Volume 2. It covers the government's decisions following the 2023 consultation on the Future Homes and Buildings Standards, which ran from 13 December 2023 to 27 March 2024 and received 2,413 analysed responses (consultation response, para 2.4, p13).

What the government proposed

The consultation presented two options for the non-domestic notional building specification (Questions 10-11):

• Option 1 (recommended) – 40% PV coverage for side-lit spaces, 75% for top-lit spaces, heat pumps for side-lit, radiant electric for top-lit, enhanced lighting efficacy and heat recovery
• Option 2 – 20% PV coverage for side-lit spaces, 40% for top-lit, same heating approach, lower overall ambition

Both options shared the same fabric approach: "mostly the same fabric requirement as currently required under the 2021 standards", with enhanced airtightness for warehouses and sports halls (Consultation Response, Section 5).

What was adopted

The government adopted a modified version of Option 1, described as having "the benefit of reduced costs compared to Option 1, making this standard more achievable for the sector, whilst still being more ambitious than Option 2" (Consultation Response, Section 2).

Solar PV decisions

The FBS policy adopted a flat 40% of foundation area for both side-lit and top-lit buildings (consultation response, para 3.10-3.11, p18). The originally proposed 75% for top-lit buildings (warehouses, sports halls) was reduced to 40%. The current NCM 2021 Equation 9 still 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, the notional building has no PV (NCM 2021, para 83).

Three important exemptions were added:

• Higher-risk buildings (those exceeding 18 metres in height) are exempt from the solar PV requirement entirely
• Buildings unable to achieve 720 kWh/year output (due to shading or orientation) are exempt
• Alternative renewable electricity generation or improved fabric/services can offset reduced PV coverage where physical constraints apply

The National Federation of Roofing Contractors raised concerns about installer competence standards and fire safety testing for rooftop solar installations (Consultation Response, Section 3).

Heating decisions

The adopted standard specifies low-carbon heating in the notional building:

• Side-lit spaces (offices, hotels, schools) – heat pumps (air-source or ground-source)
• Top-lit spaces (warehouses, sports halls) – radiant electric heating
• Heat networks – 4th-generation equivalent acceptable, providing "sufficient clean heat" with matching low-carbon generation capacity

An explicit fuel restriction was adopted: new heating systems must use fuels with a CO₂ emission factor no greater than 0.086 kgCO₂/kWh and a primary energy factor no greater than 1.969 kWhPE/kWh (AD L2 2026, para 4.4). This effectively bars fossil fuel heating in new non-domestic buildings. Additionally, new wet heating systems must be designed for a maximum flow temperature of 55°C (AD L2 2026, para 4.12).

Fabric decisions

Non-domestic fabric backstop values were retained at Part L 2021 levels: roof 0.18, wall 0.26, floor 0.18, and windows 1.6 W/(m²·K). The consultation response confirmed that fabric standards would remain "mostly the same" with enhanced airtightness only for warehouses and sports halls (Consultation Response, Section 5).

This contrasts with the domestic Future Homes Standard, where fabric targets were tightened significantly (e.g., external walls from 0.26 to 0.15 W/(m²·K)). The non-domestic approach relies on the notional building method to set overall energy targets, rather than mandating specific U-values beyond the backstops.

Lighting and building services

The consultation proposed a notional lighting efficacy of 150 lm/W (consultation response, para 12.55, p114), but the government adopted 105 lm/W following industry feedback that the higher target was not cost-effective. Display lighting was set at 95 lm/W. The adopted 105 lm/W is still a 10.5% increase from the Part L 2021 notional of 95 lm/W (NCM 2021, para 71), representing a meaningful improvement while remaining achievable with current LED technology (Consultation Response, Section 7).

Additional changes included a new heat pump seasonal efficiency calculation tool, multiple lighting system input capability in iSBEM, and updated carbon factors for all fuels (Consultation Response, Section 8).

Compliance metrics

Respondents were asked whether the existing BER/BPER metrics should be retained (Question 12). Those supporting the existing metrics cited familiarity and alignment with established industry practices. Some respondents expressed a preference for delivered energy as a metric. The government retained the dual BER/BPER approach unchanged from Part L 2021 (Consultation Response, Section 2).

Higher-risk building exemptions

Buildings classified as higher-risk buildings (those at least 18 metres in height or at least 7 storeys, and containing at least two residential units) received a later enforcement date (September 2027 rather than March 2027) and a full exemption from the solar PV requirement. The government acknowledged that rooftop PV on high-rise buildings presents unique structural and fire safety challenges.

Cost and benefit analysis

The impact assessment estimated a net present social value of £874 million over 70 years, with total carbon savings of 11.8 MtCO₂e and monetised carbon benefits of £2.0 billion. Under the preferred option, build cost uplifts range from 0.6% for hospitals to 2.6% for shallow-plan offices and hotels (FBS Impact Assessment, Table 16, p64). The Regulatory Policy Committee rated the impact assessment "not fit for purpose" due to insufficient evidence on small business exemptions and reliance on narrative rather than quantitative comparison (RPC Opinion, FBS Impact Assessment).

Implementation timeline

The consultation originally proposed implementation in 2025. The adopted timeline delayed this to 2027, providing a full 12 months between publication and enforcement. See the FBS timeline for all key dates and the transition arrangements page for transitional protection details (Building Circular 01/2026).