Qarnot moves data centre servers into the home as “heaters”

According to Frenchman Paul Benoit, today’s data centres consume around 2% of the total world energy, most of which is discarded outside as unwanted waste heat. He expects this figure to grow to 4% in five years and 8% in 10 years, but knows that there must be a better way to make use of that heat.

About 10 years ago while working in the department of a French bank, he noticed that as the bank added more and more servers, it also had to spend a lot more on air conditioning including power to cool them down. After thinking about what could be down with this waste heat, he came up with a rather simple, but clear idea for a new company, Qarnot Computing.

He has created what he calls a “Digital heater”, which is a computer server designed to be fitted like a radiator in a home, where a bank of these can heat a building. When the home owner’s thermostat calls for more heat, these servers take extra computation from Qarnot’s corporate clients. The resulting waste heat from the CPUs is released into the room and this data crunching continues until the room reaches the desired room temperature.


If not enough computing workload is available to heat the home, Qarnot offers the spare capacity to university labs for free. As for the excess computing workload or during warm days when heat is not required, the computing takes place at data centres to meet the computing requirements of Qarnot’s clients.

As those “Digital heaters” require as much electricity as an electric heater for the same amount of heat, the company reimburses the home owner for the electric running cost of the servers in the home, effectively giving the owner the heat for free, while at the same time saving Qarnot on air conditioning running costs had those servers been clustered together in a data centre.

Traditionally, large cloud computing firms such as Amazon and Google have built their data centres in places where electricity is cheap or in cold climates where cooling could be achieved without high air conditioning costs. So instead of cooling down the servers or discarding the waste heat outside, it became an obvious question – Why not use the heat?

As more and more companies need more computing power, Mr Benoit thinks that more companies will start to think about the environmental advantage of using their computers for heating in addition to number crunching.

Further info can be read in this BBC article and on the Qarnot computing website.