Warmth on Credit: Who Foots the Bill When a Council Heat Network Fails?

In a plant room off a residential street in inner London, a gas-fired boiler the size of a van is doing what it has done for nineteen winters. It pushes hot water through insulated pipes under the pavement and into several hundred homes, none of which has a boiler of its own. The residents pay for heat by the kilowatt hour. Most have never set foot in the room that produces it.

Heat networks of this kind now supply a growing share of the capital's homes, from post-war estates to new-build towers. They are central to almost every borough's carbon plan: a communal plant can run on heat pumps, waste heat from data centres or the London Underground, or eventually hydrogen, in a way that a wall-mounted combi boiler never can. But as winter 2026 sets in, the same systems are exposing a less discussed problem. The plant rooms are ageing, the repair bills are climbing, and the question of who ultimately pays is being answered differently street by street.

A utility in all but name

District heating has long been treated as a building service rather than a piece of infrastructure. That distinction matters. A householder on gas has a supplier, a regulator, a price cap and the right to switch. A householder on a heat network typically has a contract with the network operator, a standing charge, a tariff set by that operator, and very little recourse if the heat stops.

Most London schemes were built by councils or by the housing associations that took over their stock. Many are operated through arm's-length energy services companies — ESCos — wholly or partly owned by the local authority. Some are joint ventures; a handful have been sold to private operators; others sit inside the general fund and are run by a team of two or three officers who also manage the borough's other energy contracts.

That mosaic of ownership is now the source of much of the difficulty. When a boiler fails or a plate heat exchanger corrodes, the question of who authorises the spend, who carries the risk and who recovers the cost depends entirely on which model applies.

The service charge line nobody budgeted for

For leaseholders, heat network costs usually arrive in two parts: a consumption charge and a share of the maintenance of the communal system. The second is where the pressure is showing.

Officers in several boroughs report that maintenance contracts signed when gas was cheap and plant was new now look badly underpriced. Insurance premiums for plant rooms have risen. Spare parts for older combined heat and power engines can take months to arrive. Where a scheme was designed to be cross-subsidised by a commercial customer — a leisure centre, a school, a tower of private flats — the failure or departure of that customer shifts fixed costs onto the remaining households.

Councils are not obliged to absorb those costs. In some schemes the lease or tenancy agreement allows recovery through the service charge; in others the council has chosen to underwrite the shortfall from its own budget rather than pass it on. Both approaches are defensible; they are not consistent, and residents on adjacent estates can find themselves paying markedly different amounts for the same service.

Tenants in council-owned stock are in a different position again. Their heat is often bundled into rent or charged at a rate set by the landlord, and they have no route to the housing ombudsman for pricing disputes in the way they might for repairs.

The carbon promise and the repair backlog

The political case for heat networks is strong. Heating buildings accounts for a substantial share of the capital's emissions, and the Mayor's net-zero targets assume a significant expansion of communal and district heat. Government funding streams — most recently the Heat Network Efficiency Scheme and its predecessors — have paid for feasibility studies, pipework upgrades and heat pump conversions.

But grants rarely cover the unglamorous work of replacing a twenty-year-old boiler, and they almost never cover the cost of compensating residents for a cold week in January. Councils chasing decarbonisation money are therefore doing so while carrying a maintenance backlog they cannot easily price.

The risk is what the sector calls a stranded asset: a plant room that is too old to be efficient, too expensive to replace and too embedded in the fabric of a neighbourhood to abandon. For a borough already forecasting pressure on its housing revenue account, that is a liability with no obvious off-switch.

Regulation arrives, with questions attached

The regulatory picture is changing. Ofgem has been designated as the regulator for heat networks, and the market framework being phased in will bring consumer standards, price transparency and, in time, potentially price regulation for domestic customers. For residents, that is broadly welcome. For councils, it introduces a new layer of compliance to a service many have run as a quasi-domestic arrangement.

Some officers privately welcome the discipline. Others point out that a regulated utility is expected to hold capital reserves, maintain asset registers and publish performance data — obligations that small borough energy teams are not currently resourced to meet. A network that fails to meet standards could find itself on a list that town halls would rather avoid.

What residents are asking

The complaints that reach councillors and scrutiny committees are consistent across boroughs. Outages that last days. Bills based on estimates rather than meter readings. Standing charges that seem unrelated to consumption. A sense that there is no comparison site, no switching route and no one clearly accountable when the heat goes off.

Some councils have responded with resident liaison panels and clearer billing. Others have not. The gap between the best and worst schemes is now wide enough that the sector's own representatives describe it as a reputational risk for the whole model.

The reckoning on the balance sheet

The boiler rooms of London are not a glamorous subject, and that is partly why they have been left to accumulate. But the decisions now being taken — about who absorbs the cost of repair, whether to bring maintenance back in-house, how quickly to convert to low-carbon heat, and what residents are told — will determine whether district heating becomes a credible part of the capital's infrastructure or a recurring line of complaint in every borough that runs one.

Winter 2026 will not settle that question. It will, however, make the arithmetic harder to ignore.