Talk title: HNTAS, DESNZ Technical Standard for Ambient Loops & Shared Ground Loops, and preview of updated CIBSE TM51
Speaker: Ken Gordon, ADE
Event: CIBSE Scotland Conference 2026: Heating the Future, 27 May 2026
Video: https://youtu.be/i6O3xV_NlUM

[00:00] And I'm going to kind of show my age now by a reference to Monty Python. Now for something completely different. So I work with the, yes, I work with the ADE and I look after the smaller heat networks, the decentralized heat networks, which are known to Desnes as the alternative technologies, but also as shared ground loops and ambient heat networks.

[00:33] And put my glasses on so I can read this.

[00:38] So, yeah, so today I want to talk about something bigger than heat pumps themselves, because in the UK conversion around the ground source is now shifting away from individual heating technologies and increasingly towards shared infrastructure. And that changes the whole thing completely. It's no longer simply about improving building efficiency or replacing boilers.

[01:08] It's increasingly about energy infrastructure, grid stability and long life thermal assets. And maybe I should be on this one here. Yeah. So before getting into the details, this is really the journey I want to take you on through this morning. First, why shared thermal infrastructure is fundamentally changes what the systems can become.

[01:34] And second, that is why that is increasingly matters to the wider energy economy. So, I'll talk about that in a minute. Particularly around winter peak demand and grid stability third why that then changes delivery models ownership structures regulation and financing and finally why this may become especially important for scotland and the wider uk energy transition so before we go any further this is really the architectural shift center of the discussion traditionally we tend to think about ground source heat pumps as individual buildings systems connected to individual ground loops but once you move towards shared ambient infrastructure the model changes significantly you now have a shared low temperature thermal network serving multiple buildings while each building still retains its own local heat pump and importantly the same infrastructure can support heating cooling thermal balancing and seasonal thermal storage at that point the network begins to behave much less like isolated building plant

[02:38] And much more like shared utility infrastructure and that distinction becomes extremely important later when we start talking about regulation investment and long-term asset ownership to me this is where the engineering becomes strategically important because the electrical grid is not designed around annual averages and heat pump efficiencies it's designed around peaks and the challenge with heat electrification is that heating demand often rises precisely when the electrical system is already under the greatest pressure if two systems deliver the same amount of heat they are not necessarily equivalent from a grid perspective air source systems typically experience failing source temperatures during colder pray conditions which can increase electrical demand during winter peaks so ground couple systems behave differently because the thermal source is far more stable it doesn't actually cause change하는 is far more stable and that means lower and flatter electrical demand profiles during peak winter operation so increasingly the question is no longer simply does electrified heating work

[03:44] Question is can it scale without creating unacceptable winter peak electrical demand once you start thinking at system level shared ground looks become very interesting because the moment the ground array is shared the infrastructure becomes decoupled from individual buildings the thermal resource is no longer tied to one customer or one asset life cycle instead it becomes a shared long life thermal asset capable of serving multiple users in their local community that creates several important system advantages diversified loads proven utilization future connection flexibility and infrastructure longevity once those characters are integrated into the system they will be able to be used in a variety of different ways and once those characters are integrated into the system they will be able to be used in a variety of different ways and once those characteristics emerge the network increasingly starts to resemble regulated utility infrastructure rather than conventional building services engineering this is really where regulation starts to matter enormously because once shared thermal infrastructure begins serving multiple customers of very

[04:47] Long asset lives the commercial and regulatory model changes fundamentally these systems begin to resemble utility infrastructure and utility infrastructure depends on confidence that technical performance will be maintained consumers will be protected assets will remain operational long term and future revenue is sufficiently predictable to support investment that is why regulation has become strategically important in the uk because regulation is not simply about compliance it's about creating the conditions under which infrastructure capital becomes willing to invest at scale once that happens the economics change very quickly so this is how the uk is now beginning to formalize that transition policy level comes from desnes and scottish government heard from james earlier that policy direction is then underpinned legally through the energy act 2023. Off gem then becomes

[05:47] The formal regulator of the emerging market framework beneath that is hntas this heat network technical assurance scheme heat network technical assurance scheme is the most important part of the energy act 2023. Which starts translating policy ambition into technical assurance and enforceable delivery standards so what we're now seeing is the gradual construction of a complete governance architecture around heat networks and that's very significant shift because this moves heat networks away from voluntary good practice and towards regulated infrastructure delivery there it is and this is where technical standards are critically important because standards are ultimately what convert high level policy ambition into the energy act 2023. This is where technical standards are critically important because standards are ultimately what convert high level policy ambition into the energy act 2023.

[06:27] To measurable engineering delivery this document here is called ts1 technical standard one and it forms the core technical framework underpinning regulated heat network delivery in great britain and this is the one for centralized heat networks so not the one that I talked about earlier so the current work will now extend that framework to include shareground loops and ambient heat networks and the important point here is that technical assurance is no longer being treated as optional guidance and we've heard that as well it's increasingly becoming part of a regulated delivery environment and that is ultimately what creates investor confidence consumer confidence and long-term market stability one of the reasons that this becomes especially relevant to scotland is that in many rural and semi-rural areas sit awkwardly between two traditional models they're often not dense enough for conventional high temperature district heating but equally treating every building as a completely isolated energy system is not always optimal either. Shared ground loops and ambient heat networks potentially create a

[07:32] Middle ground, a way of connecting clusters of buildings, campuses, estates or communities through flexible low temperature thermal infrastructure and that will be extremely important for regional decarbonisation across Scotland. So if I was to leave you with one central message this morning it's this. Conditions required to scale shared thermal infrastructure are no longer theoretical. The engineering is already proven, the policy framework is emerging, the commercial logic is increasingly compelling and that demand assurance starts to create the long-term investment confidence needed for infrastructure scale deployment. That's really the transition now underway in the UK. This is moving from specialist engineering systems towards strategic thermal infrastructure.

[08:23] So I was asked just to talk about the some work that I did for CIBSE. I was lead author on TM51 and so we've rewritten with the steering group the whole technical memorandum on ground and water heat pumps and one of the major changes with the new document is that it increasingly reflects this system level approach. The new TM51 moves well beyond standalone heat pump design, increasingly addresses shared thermal infrastructure ambient loops, thermal storage, cooling integration, seasonal performance and wider energy system interaction.

[09:02] A major theme throughout the document is the relationship between ground coupled systems, grid resilience and winter peak demand reduction and increasingly that aligns very closely with the direction now emerging through HNTAS and technical standards. It also has an appendix on it which is designed for building services engineers which moves away from the sort of architectural state and building service engineers. So it's strong enough to fit the main components apparently the first water source heat pump apparently the first water source heat pump used for central heating was installed in Octorada over a century ago

[10:04] What is changing now is not the physics what's changing is the emergence of the policy regulatory commercial infrastructure frameworks needed to allow these systems to scale property properly and perhaps that's the real opportunity ahead not to reinvent the technology but finally to build the conditions that allow shared thermal infrastructure to become part of the mainstream energy system.