UK couple’s garden shed datacenter heats home and cuts energy bills to £40 — clusters of 56 Raspberry Pis run real workloads, waste heat converted to heat home

A garden shed that is being used as a datacenter

(Image credit: Ben Schofield/BBC)

A couple from Essex in the United Kingdom are heating their home with a small data center in their garden, according to a BBC News report. The system, described as a “HeatHub” installed in a shed, has reduced owners Terrence and Lesley Bridges' energy bills to around £40 a month by diverting the heat from server workloads into a domestic hot water system.

The setup is part of a program from Thermify, which itself is part of the SHIELD project by UK Power Networks. The SHIELD Project aims to develop new ways for low-income households to transition to net-zero. According to Thermify’s CEO and co-founder, Travis Theune, the couple’s HeatHub installation will become part of a “remote and distributed” data center — just one of many units processing customer data.

Thermify’s HeatHub is just one example of server heat being used to help offset utility bills. Deep Green, another UK firm, has installed micro data centres at leisure centres and swimming pools in Devon and Manchester. Each pod contains high-performance compute units submerged in mineral oil coolant, which is circulated through existing heat exchangers. In one deployment, Deep Green claims its waste heat covers more than 60 percent of the pool’s annual demand, saving thousands in gas bills and cutting emissions by six tonnes a year.

Neither model is suitable for DIY installation. Most UK homes are limited to a 100-amp single-phase supply, and any sustained high-power load must be carefully managed to avoid overload or fire risk. A typical combination boiler system won’t benefit from cylinder heating, and insurance or grid compliance could become an issue if systems are installed unofficially.

Still, the trend is very much on energy regulator Ofgem’s radar. It's preparing to regulate heat networks under a phased plan beginning in 2026, running through 2027. While garden-shed datacentres may not fall under its scope yet, the idea of selling reused server heat back into homes is beginning to gain formal oversight.

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Luke James is a freelance writer and journalist. Although his background is in legal, he has a personal interest in all things tech, especially hardware and microelectronics, and anything regulatory.

5 Comments Comment from the forums

edzieba

Neither model is suitable for DIY installation. Most UK homes are limited to a 100-amp single-phase supply, and any sustained high-power load must be carefully managed to avoid overload or fire risk.
What nonsense! The typical 100A service here means an average home has 23 kW steady-state load to play with before adding another phase is required. That's more than sufficient for a typical electric boiler (AKA immersion heater, which ends up being called that even if it's a combi-boiler rather than a tank system) - hence why those can be installed with no change to the home service - so whether you generate that heat by running power through a coil of wire or through some silicon ICs before transferring to the radiator loop is irrelevant.

And at 10 W for a Pi 5 at full tilt, a mere 56x Pis are not going to be pushing 1kW, let alone 23kW! That's not even a 1/6th of what your standard 13A plug will handle!

The core problem is that this is just electric resistive heating with more expensive heating elements. There is no offsetting of carbon emissions by using heating elements that do compute (and compute of questionable utility) rather than ones that glow a wire, and worse is that simple joule heating is several times less efficient than an air-source or ground-source heat pump. And unlike heat pumps, resistive heating is useless for the large portions of the year where heating is not required and cooling is required instead.
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das_stig

I do that now, just leave the bedroom door open on spare room/datacenter and warms upstairs.
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Moonstick2

edzieba said:
What nonsense! The typical 100A service here means an average home has 23 kW steady-state load to play with before adding another phase is required...And at 10 W for a Pi 5 at full tilt, a mere 56x Pis are not going to be pushing 1kW, let alone 23kW! That's not even a 1/6th of what your standard 13A plug will handle!
The article said "Each HeatHub unit consists of several modules containing up to 56 Raspberry Pi computers.". I'm guessing that each module contains up to 56, not each HeatHub. After all, 0.56 kW isn't going to heat much water.

According to The Register who covered this last month, it contains 500 RPi Compute Modules. Even 8 W per module would mean nearly 17 A from a 240 V supply. In the picture of the guy standing next to the HeatHub it certainly looks like a high-current connection on the wall behind him.
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edzieba

Moonstick2 said:
The article said "Each HeatHub unit consists of several modules containing up to 56 Raspberry Pi computers.". I'm guessing that each module contains up to 56, not each HeatHub. After all, 0.56 kW isn't going to heat much water.

According to The Register who covered this last month, it contains 500 RPi Compute Modules. Even 8 W per module would mean nearly 17 A from a 240 V supply. In the picture of the guy standing next to the HeatHub it certainly looks like a high-current connection on the wall behind him.
That's still well within the realms of a single domestic circuit, e.g. two plugs on a 32A ring would do it without issue. Or 60309 on its own spur if you really want it to be on a single socket. Or wire the PDU to a spur directly to avoid needing a socket at all.

And all nowhere close to inconveniencing the 100A service. And depending on your existing breaker, there's a good chance that could be a Part P non-notifiable work (i.e. installable by the homeowner with no electrician or inspection required), for example, adding a spur to an existing 32A ring.
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Moonstick2

edzieba said:
That's still well within the realms of a single domestic circuit...
Clearly, because the whole idea is selling these things to domestic households. Bit difficult to persuade homeowners to become part of a distributed data centre if it's going to mean completely rewiring their house with an industrial circuit.

You overlooked the "Neither model is suitable for DIY..." The 100 A is in reference to the Deep Green models mentioned in the paragraph before. Deep Green talk of heating up leisure centres and supporting up to 480 kW per rack which is why they're not suitable for 100 A domestic circuits. For the second part of the sentence the HeatHub could be pulling a continuous 17+ A so consideration would need to be given ("carefully managed") to any other loads on a circuit that is now at less than half its capacity. I'll hazard a guess that Thermify install a dedicated circuit for the HeatHub instead of dropping it off on the doorstep and leaving it up to the owner to monitor what appliances are running on which ring main when.

Hence, neither model is suitable for DIY.
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