Episode 216 - Future Homes Buildings Standard

This week we will be talking about the latest updates on the Future Homes and Buildings Standards. This episode content meets PC3 - Legal Framework & Processes of the Part 3 Criteria.

Resources from today's episode:

Websites:

• https://www.ribaj.com/intelligence/future-homes-and-building-standards-explainer/
• https://assets.publishing.service.gov.uk/media/69c13592bb0dfe55b83e4b85/Future_Homes_and_Buildings_Standards_Consultation_Response.pdf

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Transcript

Episode 216:

Hello and Welcome to the Part3 with me podcast. 

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I am your host Maria Skoutari and this week we will be talking about the latest updates on the Future Homes and Buildings Standards, a follow up to Episode 72 & 82. Todays’ episode meet PC3 of the Part 3 Criteria.

Now, if you listened to Episode 72, you’ll remember we talked about the Future Homes Standard and how it was intended to reshape domestic building design through lower carbon heating, better fabric performance, improved ventilation, and a stronger emphasis on building performance in use. Then in Episode 82, we widened the lens to look at the Future Buildings Standard and how that was expected to extend the same direction of travel into non-domestic buildings, with a particular focus on low-carbon heat, compliance pathways, and energy modelling. At the time, the plan was for these two standards to come into force in 2025, with the aim of delivering new homes that produce 75-80% less carbon than those built under the 2013 Building Regulations, and non-domestic buildings producing around 27% less carbon. 

Well, a lot has happened since those episodes, and I thought it was about time we revisited where we are now. The short answer is that the standards have landed, but they look a little different to what we were expecting, and crucially, they come into force later than originally planned. 

So today I want to take you through what's new, what's changed, and what it all means for you as an architect.

Starting with the name of the Standard:

In Episodes 72 and 82, I spoke about two separate policy strands, which was the Future Homes Standard for dwellings, and the Future Buildings Standard for non-domestic buildings. Well, the government has now rolled these into a single combined announcement called the Future Homes and Buildings Standards. 

The government's consultation response was published in March 2026 by the Ministry of Housing, Communities and Local Government, and alongside it, the amended regulations have been laid before Parliament and updated Approved Documents L and F have been published.

One small but interesting point from the consultation response is that the government has actually decided not to proceed with a dedicated Future Homes Standard brand, which had been floated as a way of marketing compliant homes. So you won't see a formal kitemark or stamp instead, compliance will simply flow through the Building Regulations in the usual way, via Approved Documents L and F.

A helpful way to think about this update is to separate domestic and non-domestic buildings, because the policy is now clearly dealing with both together, but with different compliance details.

For new dwellings, the government has set the fabric and service requirements, while taking a different approach to solar provision. In practice, that means the direction is still toward better fabric and lower carbon services, but the solar requirement has been reframed as a new functional requirement for renewable electricity generation, something we will expand on later in the episode.

Now, for new non-domestic buildings, the government has also confirmed the standards through the updated framework, including performance requirements based on Target Emissions Rate and Target Primary Energy Rate, plus updated guidance on building services, ventilation, controls, and other energy-related elements. The broader message is that non-domestic projects will continue to need a more integrated, performance-led approach, not just a checkbox exercise at the end of technical design. Again something we will expand on later in the episode

The important point here is that the standards are not asking for a single technology in every case. Instead, they are trying to secure outcomes, such as lower emissions, reduced demand, better efficiency, and buildings that can operate well as the grid decarbonises. That matters for architects because it supports a more holistic design conversation with energy consultants, services engineers, and clients from the earliest stages.

The key aim of the combined Future Homes and Buildings Standards is:

• To deliver new homes that produce at least 75% less carbon than those built under the 2013 Part L, and around 30% less than the 2021 Part L uplift that came into force in June 2022.
• To ensure all new homes are 'zero carbon ready’, meaning they will not require retrofitting to become zero carbon in use, once the electricity grid is fully decarbonised.
• To mandate on-site renewable electricity generation for all new dwellings through a new functional requirement, known as Regulation L3.
• To close the performance gap between design intent and actual in-use performance, through tighter airtightness standards, improved specification, and the provision of Home User Guides to occupants.
• To deliver estimated energy bill savings of up to £830 a year compared with a standard home achieving an Energy Performance Certificate rating of C.

The biggest new requirement from the Standards aims is the mandatory on-site renewables:

This is probably the biggest new element that wasn't in place when Episode 72 was released. The headline change under the Standard is a brand-new functional requirement in Part L, called Requirement L3, which creates a legal obligation for all new dwellings, and any buildings containing dwellings, to include on-site renewable electricity generation. In practice, this almost always means rooftop solar photovoltaic panels.

So what does compliance actually look like? The Approved Document says that, as a minimum, rooftop solar panels must cover the equivalent of 40% of the dwelling's ground-floor area, using panels with an efficiency of 0.22 kilowatts-peak per square metre. The panels must be oriented somewhere between south-east and south-west, installed at a pitch of 45 degrees, and must not be overshaded. Where these requirements genuinely cannot be met, you're expected to maximise generation output in other ways by specifying higher performance panels, alternative orientations, or other modifications.

There are some limited exemptions. Buildings over 18 metres tall are exempt, as are higher-risk buildings more broadly, and sites where limitations like heavy overshading or complex roof geometry mean that a minimum output of 720 kilowatt hours per year simply cannot be achieved. But outside of those narrow exemptions, you should be assuming that every new home practices design from 2027 onwards will have solar PV on the roof. This has real knock-on consequences for roof form, orientation of the building on the site, masterplanning, and how you arrange terraces or apartment blocks so it's worth bringing into feasibility and planning discussions early, not leaving it to technical design.

Now when it comes to heating, will it effectively be the end of fossil-fuel systems in new homes like gas:

Well, technically no, the new standards don’t contain an explicit ban on gas boilers, just as Part L 2021 didn't explicitly ban them. However, the carbon targets have now been set at a level that simply cannot be realistically achieved by any fossil-fuel heating system, including gas boilers, oil boilers, and even hydrogen-ready boilers. Direct electric heating is also effectively excluded because of its primary energy and running cost implications.

What this leaves us with in practice is three main routes for heating new homes:

• Air-source heat pumps, which will be the default for the majority of new homes, such as standalone houses and smaller developments.
• Ground-source heat pumps and shared ground loop systems, which are more relevant where you have the ground conditions and the density to justify them.
• And, heat networks with low-carbon heat sources, which remain an important option for higher-density developments, apartment buildings and mixed-use schemes where individual heat pumps are impractical.

It's worth flagging that the changes won’t affect existing homes where it will still be possible to install or replace a gas boiler under Part L Volume 1 rules for existing dwellings. So the Standard is very much aimed at the new build pipeline.

On heat networks specifically, the consultation response has refined the approach we discussed in Episode 82. The updated Approved Documents now set two routes to demonstrate compliance for a dwelling or building connected to a new or existing heat network. The first being a standardised ‘low carbon heat network' notional building for communal networks, and a revised sleeving route for district networks. And any temporary heating solutions used before a building is actually connected to a heat network will themselves need to be low carbon.

The next key area the Standard focuses on is Fabric Performance:

In Episode 72 I talked a lot about the fabric first approach, and this remains front and centre in the combined Standards. Interestingly, the maximum permitted, or ‘backstop', U-values for new dwellings under the combined Standards are unchanged from Part L 2021. What has changed are the notional U-values, which are the fabric assumptions used when the government sets the carbon and primary energy targets. Because the combined Standards use a whole-building performance approach, you can trade off between fabric and services, but in practice meeting the targets will mean fabric that is significantly tighter than the 2021 notional.

To give you some headline numbers:

• For External walls the notional U-value has tightened from 0.18 watts per square metre kelvin under Part L 2021, down to 0.15 under the Future Homes Buildings Standard. The backstop remains at 0.26.
• For Ground floors the notional U-value tightens from 0.13 to 0.11, with the backstop unchanged at 0.18.
• For Roofs the notional remains at 0.11, with a backstop of 0.16.
• For Windows the Future Homes Buildings Standard changes the approach meaning window performance is now calculated based on the actual dimensions of each opening in the design, rather than a single notional figure. In practice, triple glazing, typically with a whole-window U-value of 0.8 to 1.0, becomes the standard for most new homes. The backstop of 1.6 for windows and doors remains the same as Part L 2021.

So, what does this mean for design moving forward, it means thicker walls. Cavity walls will typically need cavities over 150 millimetres with full-fill mineral wool or partial-fill PIR. Timber frame builds will require deeper studs, typically over 140 millimetres, often with an additional external insulation layer. Masonry walls will need thicker insulation layers overall. And that all has implications for plot widths, the size of the foundations, the relationship between external and internal dimensions, and the site coverage. So again this will need to be brough it into feasibility to avoid surprises to clients later. This is particularly important for any of you working on sites that have already been acquired on standard house types, because those standard types may well not meet the Future Homes Buildings Standard in their current form. 

This is very familiar territory for architects and it means being disciplined about the basics relating to insulation continuity, thermal bridging, airtightness, opening design, junction detailing, and avoiding design moves that create avoidable energy penalties. It also means that performance can no longer be treated as something that sits only in the energy model. It has to be considered in the detailing, specification, and site inspection stages too.

The update also reinforces that buildings constructed to these standards should be zero carbon ready in use as the electricity grid continues to decarbonise. It means the ambition is not just “lower carbon today”, but “designed so that future decarbonisation of the grid delivers the rest of the carbon reduction without needing major retrofit later”.

Another one of the bigger technical shifts under the Future Homes Buildings Standard is the airtightness challenge and ventilation:

Part F 2021 had already introduced new mandatory ventilation requirements for homes. The Future Homes Buildings Standard now takes this a significant step further by introducing much more stringent airtightness limits. The notional airtightness target is now 3 cubic metres per hour per square metre at 50 pascals. That is considerably lower, in other words, tighter than both the current backstop of 8 and the Part L 2021 notional of 5. Because of that, and to keep indoor air quality acceptable, the rules effectively necessitate some form of mechanical ventilation. In most cases, that will mean either decentralised mechanical extract ventilation, or, more commonly for this level of airtightness, mechanical ventilation with heat recovery. So MVHR is moving from ‘considered best practice' to the default way of ventilating a new home under the Future Homes Buildings Standard.

Designing for this level of airtightness is going to require a genuine step change in construction quality. You'll need continuous air barriers designed and detailed from the outset, more factory-finished cassette or panelised construction methods, and very careful service penetration design. Airtightness and ventilation are completely interdependent, so you need to be considering them together, allowing space for duct runs from the central MVHR unit to every habitable room and wet room, and factoring in the acoustic impact of those ducts and the unit itself. And because overheating is amplified in well-insulated, airtight buildings, you also need to keep Part O, Overheating, front of mind. As one thing the government has now confirmed is that they will be proceeding with a full technical review of Approved Document O. So expect more on that in future episodes.

Another key consideration under the Future Homes Buildings Standard relates to compliance tools, like SAP 10.3 and the Home Energy Model:

In Episode 72 I mentioned that the Standard Assessment Procedure, or SAP, was the primary method for calculating energy performance. That is changing. The government has made available an updated version of SAP, SAP 10.3, which will be an approved calculation methodology from the launch of the Future Homes Buildings Standard. Alongside this, the government has been developing a brand-new methodology called the Home Energy Model, or HEM, which is intended to be more precise and more flexible than SAP.

HEM is expected to become an approved calculation methodology no earlier than three months after the consultation response was published, so we're looking at mid-2027 at the earliest. Once HEM is available, there will be a ‘dual running' period of at least 24 months during which either HEM or SAP 10.3 can be used to demonstrate compliance with the Future Homes Buildings Standard. HEM is the government's methodology of choice going forward, and they've committed to transitioning to it as the sole methodology at the earliest opportunity after those 24 months. So if you are working with energy consultants, it's worth asking them about their readiness for HEM, because this is going to be a meaningful change in workflow.

One theme I also spoke about in Episode 72 was closing the performance gap: 

Which is the difference between a home's design intent and how it actually performs once occupied. The  Future Homes Buildings Standard puts a real focus on closing that gap. Part L now introduces a new Regulation 40C on producing information in the right format. In practice, this mandates that developers provide occupants with a Home User Guide that includes comprehensive, accessible information on the efficient operation of low-carbon heating, ventilation, and on-site energy systems.

The Home User Guide template is not legally mandatory, it's an approved method of compliance, but whatever format you use, the guidance must now be provided both as a paper copy and a digital copy, or a paper copy with a digital copy made available. The idea is that different users refer to information in different ways, and certain groups such as elderly occupants may prefer paper. The government has commended developers who provide QR codes or online portals alongside the written guide. The proposal for a central government-run database of Home User Guides has, for now, been shelved but that's one to watch in the context of the wider conversation about building passports.

Now, in terms of Non-domestic Buildings:

The update under the combined Future Homes Buildings Standard is equally significant, even if the public conversation tends to focus more on homes.

The government has confirmed that the standard will continue to use Target Emissions Rate and Target Primary Energy Rate for non-domestic buildings, while the National Calculation Methodology remains the basis for compliance, using SBEM for simpler buildings and Dynamic Simulation Modelling for more complex ones. The government also says it will carry out a comprehensive review in 2026 of the NCM for non-domestic buildings.

The notional building approach remains central, and the response includes specific provisions for renewable electricity generation in non-domestic buildings, including photovoltaic panels equivalent to 40% of the actual building’s foundational area for both top-lit and side-lit spaces. That shows how strongly on-site renewable generation is now embedded into the regulatory direction of travel.

The standard also keeps the focus on services efficiency, commissioning, and controls and talks about updated guidance for building services, self-regulation devices, and improved treatment of ventilation, lighting, and metering. For architects, that means the design brief for a non-domestic project is increasingly inseparable from the services strategy.

So, what is the new release date for the combined Standards:

This is probably the most significant change since I last spoke about this topic. Remember, the original target was 2025. That has now shifted. The Future Homes and Buildings Standards will come into force on the 24th of March 2027, with a 12-month transitional period running until the 24th of March 2028 for buildings that have been 'commenced' by that date. What that means in practice is that for projects where a building notice, initial notice or full plans application has been submitted before the 24th of March 2027, construction can still be carried out under the existing 2021 version of Part L, provided work actually commences on that relevant building by the 24th of March 2028.

There is also a separate set of arrangements for Higher-Risk Buildings. For those, the amended regulations come into force on the 24th of September 2027, and a valid Gateway 2 application must have been submitted before that date for work to continue under the 2021 standards. There are also some knock-on changes to the older 2013 transitional arrangements that had allowed some large sites to continue building to the 2010 version of Part L, those arrangements are now being tightened so that work has to have started before the 24th of March 2028. So if you're working on a large phased site, this is one to flag with your client and your contractor early.

And finally, what does this actually mean for architects in practice:

The key implications I would say architects need to adopt is:

• Treating energy and carbon as design drivers from concept stage, not late-stage compliance issues.
• Expect renewable electricity generation to be part of normal residential design, not an exceptional add-on.
• Assume heat pumps, heat networks, and low-carbon services will be central to many schemes.
• Pay much more attention to detailing, commissioning, and handover because performance gap concerns remain central.
• Keep ventilation and overheating in the conversation whenever airtightness and fabric performance improve.

At the simplest level, the new standards are designed to make sure that new homes and non-domestic buildings are future-proofed with low carbon heating and high levels of energy efficiency, so that buildings constructed to the standards will not require retrofitting to become zero carbon in use once the electricity grid is fully decarbonised. That is the big policy intent, and it is consistent with the trajectory we discussed in the earlier episodes relating to better fabric, lower energy demand, cleaner heating, and more robust compliance.

Let’s sum up what we ran through today:

• The Future Homes Standard and Future Buildings Standard have now been combined into a single set of regulations called the Future Homes and Buildings Standards, or FHBS, with the government's 2026 consultation response published in March.
• The Future Homes Buildings Standard comes into force on the 24th of March 2027, with a 12-month transitional period to the 24th of March 2028. Higher-Risk Buildings have an alternative date of 24th of September 2027.
• The standards target at least 75% less carbon than 2013 Part L, and around 30% less than 2021 Part L, with potential energy bill savings of up to £830 a year compared to an EPC C home.
• A brand-new functional requirement, Regulation L3, makes on-site renewable electricity generation mandatory for all new dwellings. In practice, rooftop solar PV covering the equivalent of 40% of the ground-floor area will become the default.
• Gas, oil and hydrogen-ready boilers are not explicitly banned, but the carbon targets effectively rule them out for new homes – the focus shifts to air-source and ground-source heat pumps, and low-carbon heat networks for denser schemes.
• Notional U-values tighten for walls and floors, with triple glazing becoming the de-facto standard, and a new notional airtightness of 3 cubic metres per hour per square metre at 50 pascals – which effectively makes MVHR the default ventilation strategy.
• SAP 10.3 will be the approved calculation tool from launch, with the new Home Energy Model running in parallel once it becomes available and eventually replacing SAP.
• New Regulation 40C formalises the Home User Guide, with information now required in both paper and digital format, and a full technical review of Part O on overheating is on the way.

The Future Homes Buildings Standard finally gives us the clarity the industry has been waiting for. Although, the timeline has slipped to 2027, which is a frustration for those of us who wanted quicker action on carbon. But the content is, in many ways, more ambitious than what was on the table in 2023, particularly the mandatory solar PV and the much tighter airtightness target. For Part 3 candidates, the key thing to understand is not just the numbers, but the design logic of considering fabric first, low-carbon heat, on-site generation, and a genuine focus on how the building will perform in use.