As energy bills are scheduled to rise again next month, innovative domestic datacentres are offering households a way to heat water and save money. Giles Gibson, a homeowner in south-east London, has a compact computer server attached to his hot water cylinder that generates heat while operating, reducing his hot water bills by an estimated £10 to £15 a month.
Turning Waste Heat into Hot Water
Gibson's system, supplied by the Surrey-based company heata, harnesses the heat generated by a server that processes computing tasks. The device, which has the combined power of about eight laptops, is attached to his vented, unpressurised water cylinder. “As soon as I read about it, I thought: ‘This is obvious – why wouldn’t you do this?’” Gibson says. “It just makes sense to take a computer out of a datacentre and to strap it next to your water tank and get free heat.”
Heata operates a sustainable cloud computing business, sending processing jobs from its clients to servers in people's homes. The company aims to provide about 80% of the heat needed for a home's hot water, according to Charlie Beharrell, commercial director of heata. “The water in their hot water cylinder will effectively be heated by our server, and they might have to use the gas boiler for the peakier moments in the day, like when they have a bath,” Beharrell says.
How the Heata System Works
The heata system can only work in homes with vented, unpressurised water cylinders, typically recognisable by the blue insulation around the outside. Engineers cut a hole in the insulation and attach a container with the server to the front of the cylinder, gluing it with a thermal paste so the unit conducts heat without any plumbing. The installation takes a couple of hours and is free of charge.
Heata pays for the electricity used to keep the server running, while the homeowner pays for the necessary fibre broadband connection. The units are now in 100 homes, with 3,000 people on the waiting list for installation. The company says hundreds more are expected to be installed next year.
Alternative Approach: Raspberry Pi Mini Datacentres
In a separate project in Essex, two households are testing a concept where almost 500 matchbox-sized computers are stored together to form a mini datacentre. The freezer-sized HeatHub units, made by the Wales-based company thermify, recycle the energy created when computers process tasks. The heat from the rows of Raspberry Pi computers warms a mineral oil that surrounds them, which is then sent through a heat exchanger to heat water for radiators.
Thermify's chief executive, Travis Theune, says the systems will cost homeowners £90 a month for an average-sized home, with a minimum 10-year contract that includes installation, leasing, and repairs. The company claims the device will lead to a 14% reduction in bill costs compared with homes with a gas boiler, and 34% for those with a heat pump, over a 15-year period. The savings come from not having to pay for the installation of a boiler or heat pump.
