In March 2026, the government finally published the Future Homes and Buildings Standards. For most new homes in England, the new regulations come into effect on 24 March 2027. This is not a distant policy shift anymore. It will affect buildings being designed now.
The general direction is that new homes are being pushed towards low-carbon heating and much higher energy performance. The regulations also create a new functional requirement, L3, for onsite renewable electricity generation in new dwellings.
Industry reaction has broadly welcomed this clarity & update.
Heating and Ventilating reported that the standard gives developers and the supply chain the certainty they have been looking for. The MCS Foundation called it a cause for celebration as well as reflection. Thanks to this update, their research shows significant savings for households: installing solar panels and a heat pump would save a household in a typical new home over £1000 a year (increasing to £1,300 if battery storage is added).
Good Homes Alliance said it is an important step forward, but not the end of the road.
For architects, most of the attention will naturally go to heat pumps, solar PV, fabric and ventilation. But there is a system design consideration sitting in the midst all of that, i.e. hot water storage is back in the plan.
Why hot water matters more than many architects realise?
For decades the combi boiler solved an architectural problem as much as a heating one; it gave homes heating and hot water without needing a separate cylinder. And that means it freed up floor plans.
That changes once new homes move to low-carbon heating.
The Future Homes Hub has already published a dedicated heat pump guide for architects and architectural technologists because this issue is now turning up early in design. It says the guide responds to one of the most pressing challenges architects are raising as the sector moves towards the Future Homes Standard.
It also makes an important point – where early heat pump schemes have gone wrong, the issue has usually not been the technology itself, but spatial, acoustic and fabric assumptions that were fixed too early in the design process. And also that heat pumps can’t simply be ‘dropped into legacy gas-based layouts’ without triggering redesign & installation conflicts. The guide outlines different types of heat pumps and the necessary space required for a hot water cylinder.
That matters because it means this is not a problem to pore over later. It is already being recognised as an early-stage design issue.
The floor plan problem behind the Future Homes Standard
This is where practicalities need to be taken into account.
Under the Nationally Described Space Standard, built-in storage areas within the overall GIA include only a 0.5m² allowance for fixed services or equipment such as a hot water cylinder, boiler or heat exchanger. That isn’t much, especially in small flats, compact houses, modular homes or tight urban schemes, that space gets used up quickly.
The Future Homes Hub guide states that architects need to make space for emitters, cylinders, pipework, controls and other equipment within the thermal envelope of the home, and that resolving these too late can lead to common spatial conflicts and rework.
CIBSE has also said that space and integration are significant constraints, with suitable locations for heat pumps and hot water storage often difficult to find.
“So the challenge is not just that a hot water store is needed again. It is that it now has to fit inside homes that have often been designed around the assumption that a combi boiler would do that job quietly in the background.”
And that is why this becomes an architect problem now, and not later.
If the hot water strategy is left to later stages, thermal storage will need to get forced into a plan that was never designed for it, or cupboard space is lost, or pipe runs get longer.
Why hot water also matters more under HEM
There is another shift happening at the same time. The Home Energy Model is not just a new version of SAP; it is a different way of modelling performance.
HEM runs a half-hourly simulation across the whole year, which means 17,520 timesteps. Hot water demand is part of that calculation loop every 30 minutes, and energy calculation as a service (ECaaS), a cloud-based API run by MHCLG, will be the only valid route for Part L compliance under the Future Homes Standard, unlike SAP, where multiple software providers each built their own calculation engine (leading to inconsistencies between providers).
For hot water specifically, HEM goes into much more detail than SAP. It uses individual tapping events, stratified cylinder modelling and pipework losses. In simple terms, hot water efficiency calculation is being shifted from a background detail to a model that works more as a real system.
That too has a direct design implication. As the new model looks at storage behaviour, recovery, outlets and heat losses losses in more detail, the location of the hot water store, heat loss rate, and the length of piperun matter more than before. A well located & well insulated compact thermal store that doesn’t leak heat into the space, and has shorter runs would generally give a better result than a bulky hot water store in a corner of the building.
So, if hot water system details are vague or introduced late, the risk is also in compliance achievement.
What this means for architects designing homes now
Integrating renewables – a heat pump onto the site plan and adding solar PV to the roof – means redesigning how domestic hot water is included in the home layout too.
It also means making sure the hot water system is not treated as an afterthought in homes that are now expected to run on low-carbon heat and on-site electricity generation. The upcoming HEM performance calculation means selecting a thermal storage that is low heat-loss, compact and can fit into the convenient spaces in the layout.
Why compact hot water storage becomes more valuable under the new standard
Our Thermino heat battery works as a compact thermal store for projects where a traditional cylinder is difficult to fit into. It is up to 4x smaller than an equivalent hot water cylinder and has only a quarter of the heat losses of a typical old cylinder, thanks to smaller size and vacuum insulation panel lining. That matters in homes where every bit of space counts. It can help architects avoid sacrificing valuable cupboard space or compromising on room design just to accommodate hot water storage.
It also helps support a lower loss hot water system from the start, which becomes more important as homes are designed around heat pumps, on-site renewables and tighter energy targets.
We provide BIM models and SAP technical notes because this is exactly the sort of decision architects and design teams need to test early.
For architects, the value is that compact thermal storage can help protect cleaner layouts and free up locations where a traditional tank would be impossible, whether that is under stairs, inside smaller cupboards or under kitchen worktops.
Under the Future Homes Standard, some form of hot water storage becomes part of the living reality of designing low carbon homes. The question is what kind of storage enables you to free up floor space while still achieving compliance?
Over 35000 heat batteries are installed in homes across the UK and beyond
Thermino heat batteries are already being used in the kinds of projects architects are working on now. In London, the Whetstone Green Apartments show how compact thermal storage can work in a net-zero urban housing scheme alongside rooftop solar PV. In Edinburgh, the LAR Housing Trust project used Thermino with Kensa Shoebox heat pumps in a historic church conversion and adjacent new build homes, helping deliver modern heating and hot water within tighter floor plans. And in Gentoo’s Core 364 project in northern England, compact in-flat Thermino storage helped make a ground source heat pump retrofit possible across seven tower blocks without decanting residents. Together, these projects show the same thing: compact hot water storage can help architects and housing teams solve space constraints while still supporting low-carbon design.
The question is whether the hot water storage problem is being resolved early enough, and intelligently, to avoid becoming the thing that compromises the rest of the design.
That is exactly why we think compact hot water storage deserves to be assessed much earlier in the design process than it often is today.
Explore Thermino for your next project or speak to our team by clicking here.
Frequently asked questions
When does the Future Homes Standard actually start?
For most new homes in England, the regulations come into force on 24 March 2027. Transitional provisions are limited, so schemes being designed now need to be tested against that timeline.
Why does hot water become a bigger design issue under the Future Homes Standard?
Because low-carbon heating brings hot water storage back into the home. Once the combi boiler is swapped out, the thermal store for hot water needs space, pipework and efficiency. That affects layouts much earlier than teams are used to.
Has anyone else in the sector flagged this issue?
Yes. The Future Homes Hub guide for architects already treats cylinder location as an early design stage decision, and CIBSE has also highlighted how difficult it can be to find suitable locations for heat pumps and hot water storage where space is constrained.
Why does HEM make this more important?
Because HEM models hot water in much more detail than SAP, including tapping events, thermal storage behaviour & heat losses, and pipework losses. It also relies on better project data, so late may impact compliance.
What should architects do first?
Start by deciding the hot water strategy at concept stage, not once the plan is already fixed. That means thinking about location, space, pipe runs and product data early.
Why is compact thermal storage important?
Because it frees out spaces in tighter home layouts. Our specifier resources also provide BIM models and SAP technical notes, which helps teams test fit and compliance earlier.
