Heat as a Service - MyBoiler.com

In 2019–20, Bristol Energy and Baxi Heating worked with Energy Systems Catapult to pilot a mobile-phone-style ‘heat-as-a-service’ offer. This guide explains what that means, how the trials worked, and what happened next, using the organisations’ own published write-ups.

Checked October 2026. Figures and quotes below come from Energy Systems Catapult, BBC News, Ofgem, and other named public sources. If a number is not cited, it is not stated. Trial results are from small Living Lab samples, not the whole UK market.

What heat as a service is

On a normal UK gas tariff you buy kilowatt-hours (kWh) of fuel. You also buy (or already own) the boiler, the controls, and usually a separate service or cover plan. How warm the house feels is your problem: a cold snap, an empty loft, or a boiler that short-cycles all show up as a bigger bill or a less comfortable room.

Heat as a service (sometimes written HaaS) flips that. Energy Systems Catapult’s definition is that you pay for the outcome — feeling warm when and where you want — instead of for units of energy. In their trials that outcome was sold as Warm Hours on a Heat Plan: a price for keeping the home at the temperatures you asked for, for a set number of hours, rather than a price per kWh of gas.

The mobile-phone comparison is theirs, not a slogan invented here. Catapult and Baxi described a Heat Plan the way a phone contract bundles the handset with calls, texts and data: the heating appliance, servicing, maintenance and the energy needed for comfort, for a fixed weekly or monthly price. The price was meant to stay fixed whatever the weather did.

That only works if someone can measure the home. The trials used smart heating controls with room-by-room, hour-by-hour data, so the offer could be priced from the thermal performance of that house and the household’s actual schedule. Without that data, a provider is guessing — and either the customer or the provider loses money.

Catapult’s stated reason for the model was not a cheaper gas bill as such. Their research, they say, shows people care more about getting warm and comfortable than about which device delivers the heat. If a provider can guarantee comfort at a known price, households may be more willing to switch from a gas boiler to a heat pump, a heat network, or another low-carbon system when the boiler is due for replacement. See choosing a new boiler for the usual replacement path, which is still how almost every UK home does this.

How the Living Lab trials worked

Energy Systems Catapult ran the work as part of the Smart Systems and Heat programme. Phase 2 (2017–2019) was funded by the then Department for Business, Energy & Industrial Strategy. The test bed was Catapult’s Living Lab: around 100 real homes, described in 2020 as spread between Newcastle, Manchester, the West Midlands, Gloucestershire and Bridgend in Wales. Each home had a smart heating system with room-by-room temperature control and a data feed on how the house performed and how people used it.

An earlier SSH2 insight report (June 2019) summarised what trialists did when they were offered Heat Plans:

They preferred the idea of a fixed price for heat as a service over paying for units of fuel, and found Warm Hours easier to understand than kilowatt-hours.
Half chose one of the three Heat Plans on offer.
Those who bought a plan “enjoyed knowing they would get the comfort they wanted for a predictable price”. On average they paid more for heat as a service than they had been paying for their energy. That is Catapult’s own finding, not a saving claim.
Two-thirds said they would be more likely to recommend their supplier if it offered Heat Plans.
58% of trialists who had bought a Heat Plan were open to a low-carbon alternative when replacing their gas boiler, against “around 36% of owner-occupiers in the general population”. That rose to 85% if the provider could guarantee the comfort they wanted at a price they were willing to pay.

Those percentages are from a research trial, not a product launch. The homes already had the smart controls fitted. That is a different starting point from a typical UK house on a standard tariff and a wall thermostat.

Bristol Energy: the first supplier trial

On 6 February 2019 Catapult announced that Bristol Energy had become the first UK energy supplier to trial selling heat as a service rather than kWh. Bristol Energy was a council-owned supplier, founded in 2015 during Bristol’s year as European Green Capital.

The commercial trial ran for a year from February 2019. Catapult’s February 2020 write-up says the Bristol Energy Heat Plan was offered to 85 of the 100 Living Lab homes (the other 15 were on other trials). Households could compare two offers on a digital Energy Services Marketplace:

a fixed number of Warm Hours, priced from their existing heating schedule
a pay-as-you-go option with a price per Warm Hour

A sub-set of those households signed up. Catapult reported the most common reasons as “improved control and comfort” and “certainty of price”. It did not publish, in that article, how many signed up or what they paid. This page does not invent those numbers.

Samantha Nicol, then Head of Innovation at Bristol Energy, said the trial was “an important step in our journey to creating energy products which are fairly priced for everyone” and that the company was “continuing to pursue research development in this area with new trial offers coming soon”. Those later offers were overtaken by the company’s sale — see where it stands now.

Baxi: bundling the boiler into the plan

Separately, Catapult worked with Baxi Heating UK from 2019 on a Heat Plan that bundled a replacement heating system with servicing, maintenance and the energy for comfort, for a fixed monthly price — the mobile-phone-style contract described above.

The offer went to 20 Living Lab households that already had the smart controls and already knew what a Heat Plan was. Catapult’s published results were:

13 wanted to discuss the offer
10 said they liked it and were enthusiastic
1 accepted and had a boiler installed — the only one of the 20 who had an old, inefficient boiler they were ready to replace

That is a genuine sale, and it is also a reminder of how small the trial was. Interest is not the same as a mass-market product.

A later Catapult project page (July 2021) says the work then pointed Baxi toward social landlords and new-build: a fixed-price Heat Contract including gas, a connected boiler, controls, service and repair, with a “Heat Service+” idea of upgrading to low-carbon heat at the end of the contract. Baxi also joined an Innovate UK “Digital Servitisation Demonstrator” project. Those are roadmap statements from 2021. They are not evidence that a homeowner can buy a Baxi Warm Hours plan today. Baxi’s current public consumer pages advertise conventional maintenance and support plans (servicing and breakdown cover), which is boiler cover, not heat as a service.

Hybrids in the same lab

The same February 2020 Catapult article reports a hybrid trial in 5 of the 100 homes: an electric heat pump added beside the existing gas boiler, run with the smart controls as part of a Heat Plan. The hybrids reached the same comfort as the boiler alone. The heat pump’s share of the heating in those five homes was 6%, 17%, 44%, 59% and 63%, depending on how each household used the controls. Four of the five said they would be open to removing the gas boiler and relying on a heat pump if they could buy their heat as a service. See hybrid heat pumps for what that system is.

Pros and cons for a homeowner

The trials were small and selected. The list below is what those write-ups actually support, plus the obvious contract risks that follow from the model. It is not a prediction of what you would pay.

	What the idea offers	What to watch
The bill	A fixed price for a defined comfort schedule, so a cold week does not automatically mean a larger gas bill.	Catapult reported that Heat Plan buyers paid more, on average, than they had been paying for energy. Predictable is not the same as cheaper. You need the tariff, the hours included, and what happens if you use more.
Comfort	You buy temperatures in rooms at times, which most people understand better than kWh. Trialists who switched to Bristol Energy’s plan most often cited control, comfort and price certainty.	The guarantee is only as good as the contract: which rooms, which set-points, whether hot water is included, and what counts as a Warm Hour.
The boiler and repairs	A full bundle can include the appliance, servicing and maintenance, so a breakdown is the provider’s problem rather than a sudden quote.	You may not own the boiler. Ending the plan, selling the house, or wanting a different installer can be messy. Read who owns the kit and who can work on it.
Efficiency	The provider has a reason to use less fuel to deliver the same warmth — better controls, a lower flow temperature, insulation, a heat pump instead of a boiler.	That incentive only exists if the contract really is for comfort, not for kWh passed through. If the “plan” is just finance plus a normal gas tariff, the incentive is yours, as now. Practical savings without a new contract are on money and energy saving.
Low-carbon heat	Catapult’s SSH2 report found Heat Plan buyers more open to replacing a gas boiler with a low-carbon system, especially with a comfort-and-price guarantee.	That was stated preference in a trial, not a national switching rate. A heat pump still has to fit the house.
Data and lock-in	Room-level data is what made a fair, house-specific price possible.	A provider sees how you live. Switching away may mean losing the controls, the tariff, or both. The supplier also has to stay in business — see Bristol Energy below.

Where it stands now (October 2026)

Bristol Energy did not become a national heat-as-a-service supplier. In September 2020 BBC News reported that Bristol City Council sold the residential customer base — about 155,000 meter points — plus the brand and systems to Together Energy for £14 million, after earlier selling the business book to Yü Energy. The council had invested £36 million since 2015; the company had posted losses of more than £32 million.

Together Energy Retail Ltd (Ofgem’s January 2022 notice says it included Bristol Energy as a subsidiary) then ceased trading on 18 January 2022, with around 176,000 domestic customers. Ofgem appointed British Gas as Supplier of Last Resort. Those customers moved onto a normal licensed supply. There is no public evidence that the Living Lab Heat Plans survived those transfers.

Can you buy heat as a service today? As of October 2026 this site has not found a licensed UK domestic supplier selling a mass-market Warm Hours Heat Plan of the Bristol Energy type — a tariff that charges for hours of warmth instead of kWh, with a weather-independent comfort price. A 2025 Green Home Finance Accelerator discovery report published on GOV.UK (City Science, Legal and Commercial Structuring of Heat as a Service) still described the model as having “no current deployment in the UK”. That matches what is on supplier websites: heat-pump time-of-use tariffs, boiler finance, and cover plans, not Warm Hours.

Things that look adjacent, but are not the same product:

Boiler cover and manufacturer care plans — a monthly fee for servicing and repairs. You still buy gas in kWh. See boiler cover.
Boiler finance or hire-purchase — you spread the cost of a new boiler. The fuel bill stays a normal tariff. That is paying for the appliance, not for warmth.
Heat-pump finance — some suppliers and installers let you spread the cost of a heat pump (sometimes with the Boiler Upgrade Scheme deducted). You still pay for electricity in kWh. Octopus Energy has published a Cosy Home Plan of this kind; others exist. They are finance products, not Warm Hours tariffs.
Energy-as-a-service pilots — in August 2025 E.ON Next described Next Gen Home as a 20-home trial packaging solar, a battery, a heat pump, an EV charger, energy and maintenance into one monthly payment, with a wider launch “aimed for 2026”. That is closer to a bundled subscription than to selling Warm Hours. This page has not verified a UK-wide retail launch. Check the live E.ON Next pages if you want the current offer.
Heat networks — some flats already pay a heat supplier rather than a gas supplier. Billing is often still in kWh of heat, measured with a heat meter, plus a standing charge. That is a different market with its own regulations.

Government interest has not gone away. The 2025 Warm Homes Plan discussion of a Warm Homes Finance facility includes subscription or “energy as a service” models as something a call for evidence (then planned for early 2026) might look at. That is policy exploration, not a product you can switch to.

For most households the practical route is still the ordinary one: use less heat where you can (money and energy saving), keep the boiler serviced by a qualified installer, and when it is time to replace it, decide between another boiler and a heat pump. Repair, replace or heat pump is the starting point on this site.

Money and energy saving
Boiler cover
Energy — who supplies the gas, and who owns the pipes
Modulating boilers and smart controls
Heat pumps and hybrid heat pumps
Heat meters
Choosing a new boiler
Repair, replace or heat pump

Sources

Guidance only. Heat as a service is not a regulated tariff name. Contracts, ownership of the appliance, and who may work on gas or electrical equipment are all job-specific — use a qualified installer and read the live contract. Trial percentages are from Energy Systems Catapult’s published Living Lab write-ups, not from a national survey by MyBoiler.