There’s a new way for homeowners to save money on their heating bills: by turning their living rooms into data centers.

Startups in Holland, France, and Germany are reimagining the conventional data center model, placing servers inside people’s homes instead of out-the-way data farms. In the process, they hope to heat homes from excess computer heat, while lowering costs for their clients.

“It’s greener, more socially responsible because you’re helping a household make ends meet, and you save money,” says Boaz Leupe, CEO of a Dutch company called Nerdalize.

Nerdalize recently announced a trial with Eneco, Holland’s second biggest utility, whereby five homes will install server units disguised as radiators. In return, owners are reimbursed for the electricity the servers use and get to enjoy the excess heat from the computers–which is considerable.

Leupe says 60% of the cost of conventional data farms comes from buying up and putting in the required building. Nerdalize, he says, can reduce costs for its clients by about 50% by hosting in people’s homes instead. Eneco, which has a minority stake in the startup, says households can save about $440 a year on their heating bills.

Leupe insists there are no privacy or security concerns about storing data in people’s homes. One, the company knows if someone is tampering with its box. Two, the data is encrypted. And three, it’s distributed–anyone wanting to hack the network would have to know which households are carrying out work they’re interested in.