Shared Ground Loop and Networked Ground Source Heat Pumps

A shared ground loop array is a single network of underground pipes that serves several homes at once, with each home running its own ground source heat pump connected to that network. Instead of every household drilling its own boreholes or digging its own trenches, one array of boreholes is shared across a street, an estate or a block of flats, and the heat pumps sit inside each dwelling. The model is recognised in the rules of the Boiler Upgrade Scheme, which lists "ground source heat pumps as part of a shared ground loop" as an eligible technology, subject to a combined capacity limit of 300 kWth across all the heat pumps on the loop¹.

The idea matters because it solves the two problems that stop most UK households choosing ground source heating: the cost of the groundworks and the lack of land. One drilling operation serves many homes, and homes with no garden at all, including flats, can draw heat from the ground beneath the street. Under the ECO4 energy efficiency scheme, a ground source heat pump "may also be comprised of a shared ground loop, considered as a DHC variant measure type"², which shows how far the model has moved from a niche idea into official policy. For a household, the prize is the efficiency and quietness of ground source heating without owning the ground array yourself.

One ground array, many heat pumps

The defining feature of a shared ground loop is that the ground side is collective and the heating side is individual. Lengths of pipe are buried in the ground, either in a borehole or a horizontal trench, and the pipe is usually a closed circuit filled with a mixture of water and antifreeze⁷. In a shared array, many of these closed circuits are brought together to a common manifold, and from there each dwelling is served by its own connection. Each home then has its own heat pump, its own controls and its own electricity meter.

This is what distinguishes a shared ground loop from the more familiar picture of a single house with its own private array. The heat source is the same in both cases: ground source heat pumps transfer energy from the natural heat stored in the earth to heat the home and domestic hot water⁸. What changes is ownership and scale. The buried infrastructure becomes a shared asset, closer in character to the water main or the electricity cable in the street than to a household appliance, while everything above ground inside the home remains the householder's own.

The model is now written into several government schemes, which is the clearest sign that it is treated as a mainstream option rather than an experiment. The Boiler Upgrade Scheme's installer guidance sets the boundary at 300 kWth total for shared ground loop systems⁹, a limit that comfortably covers a street of typical homes given that the median capacity of a ground source installation in England and Wales is 10.5 kW⁵. ECO4, the energy efficiency obligation scheme, treats the shared ground loop variant of a ground source heat pump as a District Heating Connection measure type². For a household's energy independence, the appeal is straightforward: heat from beneath your own street, converted by a machine you own, with no flue, no fuel deliveries and no outdoor fan unit.

Boreholes, brine and a heat pump in every home

Underneath the shared model sits ordinary ground source heat pump engineering. The pipe circuit, often called brine once filled with the water and antifreeze mixture⁷, absorbs heat from the ground and carries it to the heat pump in each home, which raises the temperature to a level useful for space heating and, in some cases, pre-heating domestic hot water⁷. The ground stays at a stable temperature year round, which is why the same array can serve every home through winter without the performance swings an outdoor air unit faces.

The groundworks take one of two forms. A borehole is only about 20 cm wide, but somewhere between 75 and 200 metres deep⁴. Slim, deep boreholes are the usual choice for shared arrays in built-up areas, because a rig can drill them in a street, a car park or a patch of communal ground without opening up large trenches. The alternative is horizontal looping: for a new-build three-bedroom house, expect two trenches of 30 to 40 metres in length⁴. At street scale, horizontal trenches need far more land than most existing estates can spare, which is why borehole arrays dominate the shared model.

What drives the cost and practicality of the ground side is access: whether the ground is reached through trenches or a borehole, the size and heat need of the property, whether it is a new build or an existing property, and whether radiator or underfloor heating upgrades are needed⁴. In a shared scheme, the drilling cost is spread across all the homes on the loop, which is the whole economic argument for the model. Each household's heat pump is sized to its own home, so a small flat and a large house on the same loop pay for machines appropriate to their needs while sharing the one asset that neither could afford alone.

Shared loop, heat network or individual array: which is which

Three arrangements get confused, and the differences matter for bills, rights and grants.

• Individual ground array. One home, one set of boreholes or trenches, one heat pump. The householder owns and pays for everything.
• Shared ground loop. Many homes, one ground array, one heat pump in each home. The ground side is shared; the heating and the billing are individual.
• Heat network. One central heat source, whether a boiler plant, a large heat pump or a district connection, serving many dwellings through insulated pipes carrying hot water. Heat is produced centrally and sold to residents.

The official rules draw the boundary firmly. In the Future Homes and Buildings Standards, communal heat network systems, "where multiple dwellings or units within one a single building are served from a central heat source in that building, cannot use this route to compliance"¹⁰. A shared ground loop is different precisely because there is no central heat source: every dwelling has its own heat pump, and the only thing shared is the ground. Under ECO4's mid-scheme change rules, a District Heating Connection "does not include a connection to a district heating system that uses a shared ground loop"¹¹, an explicit statement that the two are treated separately in the scheme's administration.

That distinction runs through to the householder's daily experience. On a heat network, heat arrives as a product, metered and billed by the network operator, and residents who pay the landlord or site owner by meter readings do not have the right to choose their own energy supplier¹². On a shared ground loop, each home buys only electricity, from whichever supplier it likes, and the heat itself is produced on the premises. The ground array is infrastructure; the heat is yours.

Flats, dense estates and street-by-street schemes

Shared ground loops earn their place where individual arrays cannot fit at all. Flats are the clearest case: a household in a mid-floor flat has no ground of its own, no garden and usually no permitted development rights either, since the rights that apply to many common projects for houses do not apply to flats, maisonettes or other buildings¹³. Householder planning consent likewise does not cover applications affecting flats, more than one house or changes of use, and full planning permission is needed for those¹⁴. A shared array sidesteps all of this by putting the groundworks in communal or highway land under one scheme-wide consent, with the heat pumps sitting inside each dwelling as internal appliances.

The funded programmes show the scale at which the model is being deployed. Warm Homes: Social Housing Fund Wave 3 expects heat pumps and low carbon heat networks optimised for low flow temperatures first, then, in priority order, shared ground loops or ground source heat pumps, air to air heat pumps, heat batteries, high retention electric storage heaters in electrically heated flats and small dwellings, or solid biomass¹⁵. Wave 3 Challenge Fund applications must include a minimum of 100 eligible social housing properties at EPC band D or G per application, and mixed tenure blocks or terraces can be treated in their entirety as long as there are at least 30% social homes in the block or terrace¹⁵. At the top end, Strategic Partnership applications are expected to deliver 3,000 to more than 6,000 homes¹⁵.

Retrofit programmes in dense housing are already using the approach. Edinburgh's High Rise Retrofit and Upgrade Programme Phase 1 covers 10 high rise blocks across Craigmillar and Peffermill Court, Cables Wynd and Linksview House, and the six Moredun blocks, with proposals for significant improvements in thermal performance¹⁶. For residents of flats and dense estates, the shared model is often the only route to ground source heating, and it brings the efficiency of that technology to homes that would otherwise be left on electric heating or communal gas plant.

What changes for the householder

Living on a shared ground loop changes the shape of your heating in ways that are mostly in the householder's favour. There is no outdoor unit: the heat pump sits inside the home, typically in a cupboard or utility space, so there is no fan noise outside, no clearance distances to worry about and nothing to site in a garden. The rules that restrict how many air source heat pumps a dwelling may have under permitted development, one only for most dwellings and flats, two for detached houses¹⁷, simply do not arise, because the shared loop model puts the machinery indoors and the pipes underground.

Billing changes too, and this is the part worth understanding before joining any scheme. If you pay a supplier directly for the electricity or gas you use at home, you can choose to switch to a different supplier or tariff at any time¹⁸. That rule applies to a home on a shared ground loop, because the only energy being purchased is electricity for your own heat pump. The same protection extends to rented properties: if you have to pay your energy bills, you can choose to switch your supplier or tariff at any time¹⁸. This is a genuine difference from heat network arrangements, where residents paying a landlord or site owner by meter readings or estimates do not have the right to choose their own energy supplier¹².

The dependence that remains is on the shared ground array itself and on whoever owns it. A household on a shared loop is independent of gas, of oil deliveries and of a heat network operator's tariffs, but it depends on the condition of the buried pipes and on the governance of the scheme that owns them. Those are questions to ask before signing anything: who owns the array, what the long-term maintenance arrangement is, and what happens if the scheme's owner changes hands.

Costs and grants: £7,500 towards each heat pump

The grant position is clear and favourable. The Boiler Upgrade Scheme offers £7,500 towards a ground source heat pump, including water source heat pumps and those on shared ground loops³. The same £7,500 figure appears in the scheme's installer guidance for ground source heat pumps, with vouchers valid for 6 months¹⁹, and the grant value has applied since 21 July 2026 under the current guidance¹⁹. Because each home on a shared loop has its own heat pump, each household's installation is a grant-eligible project in its own right, subject to the scheme's rules.

The groundworks costs are where the shared model changes the arithmetic. Official statistics for England and Wales put the nominal median cost of a ground source heat pump installation at £27,232 in 2026 Q2, including the grant value, with a lower quartile of £18,136 and an upper quartile of £42,110⁵. Those figures cover ground source installations generally, and the ground array is a large part of what drives the spread, since access to the ground and the choice of trenches or borehole are among the main cost factors⁴. In a shared scheme, the drilling is done once for many homes, which is the basis on which the model is promoted for street-scale deployment.

Take-up so far has been small. Shared ground loop ground source heat pumps accounted for 29 grants, 0.05% of all grants paid to date under the scheme, as of the quarterly report to July 2025, with just 2 paid in the May to July 2025 quarter⁶. Cumulatively, ground source heat pumps of all kinds saw 2,388 voucher applications, 2,024 vouchers issued and 1,567 redemptions paid between May 2022 and July 2026 in England and Wales⁵. The model is established in the rules but still early in the market, which is worth knowing when judging any installer's or scheme promoter's claims of proven scale.

Running costs, efficiency and bills

What a household actually pays to run a heat pump on a shared loop is the electricity its own machine consumes, on whatever tariff the household has chosen. Ground source heat pumps draw on the stable temperature of the ground, which supports efficient operation through the heating season, and the shared array spreads the cost of reaching that resource. Because each home has its own heat pump and its own supplier contract, running costs are not pooled, metered centrally or subject to a network tariff: they follow the household's electricity use and tariff choices¹⁸.

The funded schemes treat shared ground loops as a priority technology for exactly this reason. Warm Homes: Social Housing Fund Wave 3 sets out its expected measures in priority order, with heat pumps and low carbon heat networks optimised for low flow temperature below 55°C first, then shared ground loops or ground source heat pumps¹⁵. The low flow temperature requirement matters to residents because it shapes the whole system design: heat pumps running at lower flow temperatures are the most efficient, and the scheme rules push landlords towards that configuration.

Evidence from retrofit programmes points to substantial carbon outcomes, which track the efficiency of the heating system. In Edinburgh's high rise programme, electrification of the heating system has shown significant carbon emission reductions between 67 and 85%¹⁶. For residents, the bill outcome depends on the heating being replaced: moving from electric storage heaters or communal gas to a heat pump on a shared loop changes both the unit cost of heat and the control each household has over it. The independence gain is real, but it is an independence from fuel and from communal billing, not from the electricity grid: the home still buys every unit of energy it uses, as electricity, from a supplier of the household's choosing.

Heat the Streets and the retrofits proving the model

Street-scale shared ground loop schemes, of which the Cornwall "Heat the Streets" retrofit is the best known example, exist to demonstrate that the model works in ordinary UK streets, not just on paper or in a single flagship building. The concept is simple to state: drill once under a whole street, connect every home, and let each household run its own heat pump. The evidence base for retrofit at scale in dense housing is being built by programmes such as Edinburgh's High Rise Retrofit and Upgrade Programme Phase 1, which covers 10 high rise blocks across three areas of the city, with proposals for significant improvements in thermal performance alongside the electrification of heating¹⁶.

The Edinburgh programme's figures give a sense of what deep retrofit plus electrified heating can deliver: carbon emission reductions between 67 and 85% where the heating system has been electrified¹⁶. Those reductions come from coupling better thermal performance with heat pumps, which is the same combination the funded schemes push for. For social housing residents, the appeal of the shared loop model is that the ground array is funded and owned at scheme level, while the household gets the heating system and the bills arrangement of an individual heat pump.

The market numbers show how early the street-scale model still is. Shared ground loop ground source heat pumps have accounted for 0.05% of Boiler Upgrade Scheme grants paid to date, 29 in total, with 2 paid in the May to July 2025 quarter⁶. Street-scale schemes are therefore best understood as demonstrations and social housing programmes at this stage rather than a mass-market option a householder can simply order. Where a scheme exists on your street or estate, the questions to ask are the ones this page sets out: who owns the array, what the grant position is, and what your supplier and switching rights will be.

Installation, permits and ground infrastructure built to last

The planning position for the heat pump itself is favourable. The installation of a ground source heat pump or a water source heat pump on domestic premises is usually considered permitted development, not needing an application for planning permission²⁰. If you live in a listed building or a conservation area, local requirements need checking with the council before any work starts²⁰. For a shared scheme covering a whole street or block, the array and the pipe runs will be handled under whatever consents the scheme organiser secures, and flats, which do not have the same permitted development rights as other properties, are directed to consult the planning team about any proposed works²¹.

The technical standards for the ground array are set out in the approved documents. Ground arrays, including header pipes and manifolds, should be flushed as one system to remove all debris and purged to remove all air²². A pressure test in accordance with BS EN 805 should be conducted for closed-loop installations²². Commissioning information provided to the dwelling owner should include details of the fluids used and their commissioned concentrations²². These are the checks that matter most on a shared array, because a fault in the common groundworks affects every home on the loop, not just one.

The buried pipe network is the part of the system designed to outlast everything else. For comparison, feed-in tariff support periods, the majority of installations running 20 years²⁴, show how long government expects ground-mounted energy infrastructure to serve; a buried plastic pipe array with no moving parts is expected to serve for far longer still, and scheme promoters routinely describe the ground array as a century-scale asset for the street. The heat pumps themselves are the shorter-lived components, replaced household by household as they age, while the array beneath carries on serving whoever lives there next.

Where a shared ground loop is not the answer

The model has firm boundaries, and they are worth stating as plainly as the benefits. The Boiler Upgrade Scheme caps the combined capacity of all heat pumps on a shared loop at 300 kWth¹, which sets an upper limit on how many homes one scheme can cover under the grant. Take-up remains tiny, 0.05% of grants paid to date⁶, so a householder outside an organised scheme will struggle to find one to join: this is a model that arrives with a housing association, a council or a developer, not one an individual household commissions alone.

The rules for funded schemes also carve out specific conditions. Under ECO4, a District Heating Connection using shared ground loops installed in social housing at SAP band D needs to be an innovation measure, while for all other tenure types it does not need to be an innovation measure²⁵. A connection to a district heating system that uses a shared ground loop is excluded from the District Heating Connection measure altogether under the mid-scheme change rules¹¹. These are administrative boundaries, but they shape what funding a particular scheme can draw on, and therefore what it can offer residents.

For the individual householder with a garden, a private array may remain the simpler path, since a single home avoids the governance questions of a shared asset. And the shared model does not remove every dependence: the home remains connected to the electricity grid for every unit of heat, the heat pump itself depends on its manufacturer and installer, and the household depends on whoever owns and maintains the buried array. What a shared ground loop offers is not off-grid living but a different balance: collective ownership of the ground, individual ownership of the heat, and a supplier relationship the householder controls.