Turn On the Server. It’s Cold Inside.

TO satisfy our ever-growing need for computing power, many technology companies have moved their work to data centers with tens of thousands of power-gobbling servers. Concentrated in one place, the servers produce enormous heat. The additional power needed for cooling them — up to half of the power used to run them — is the steep environmental price we have paid to move data to the so-called cloud.

Researchers, however, have come up with an intriguing option for that wasted heat: putting it to good use in people’s homes.

Two researchers at the University of Virginia and four at Microsoft Research explored this possibility in a paper presented this year at the Usenix Workshop on Hot Topics in Cloud Computing. The paper looks at how the servers — though still operated by their companies — could be placed inside homes and used as a source of heat. The authors call the concept the “data furnace.”

They acknowledge that it is more likely that data furnaces, if adopted, would be placed first in basements of office and apartment buildings, not in individual homes. But as a “thought-provoking exercise,” the authors give homes the bulk of their attention.

If a home has a broadband Internet connection, it can serve as a micro data center. One, two or three cabinets filled with servers could be installed where the furnace sits and connected with the existing circulation fan and ductwork. Each cabinet could have slots for, say, 40 motherboards — each one counting as a server. In the coldest climate, about 110 motherboards could keep a home as toasty as a conventional furnace does.

The rest of the year, the servers would still run, but the heat generated would be vented to the outside, as harmless as a clothes dryer’s. The researchers suggest that only if the local temperature reached 95 degrees or above would the machines need to be shut down to avoid overheating. (Of course, adding a new outside vent on the side of the house could give some homeowners pause.)

According to the researchers’ calculations, a conventional data center must invest about $400 a year to run each server, or about $16,000 for a cabinet filled with 40 of them. (This includes the costs of building a bricks-and-mortar center and of cooling the machines.)

Having homes host the machines could reduce the need for a company to build new data centers. And the company’s cost to operate the same cabinet in a home would be less than $3,600 a year — and leave a smaller carbon footprint, too. The company’s data center could thus cover the homeowner’s electricity costs for the servers and still come out way ahead financially.

THE machines would remain under the remote control of the company’s centralized data center, and their workings would remain opaque. Network traffic and data would have to be encrypted. Sensors would warn if the cabinet was opened. If a server failed, its tasks would be automatically reassigned to another — in cloud computing, software is built with the expectation that an individual machine can break at any time.

A data furnace would be best suited for computing tasks that aren’t time-sensitive and can be broken into chunks performed by thousands of machines — say, for scientific research.

The idea awaits one big-name Internet company to give it a try — and to be willing to give prospective users enough financial incentive so they’ll consent to have servers take the place of their furnaces in the basement.

I asked Kamin Whitehouse, an assistant professor of computer science at the University of Virginia and a co-author of the research paper, how the computer science world had reacted to the idea. “We’ve gotten a very strong response, more than I usually get after publishing a scientific paper,” he said. “We heard from several people who are already heating their homes with computer systems, which shows that it works. Our contribution is to show that the data furnace also has lower cost and lower energy than a conventional data center.”

Winston Saunders, a physicist who serves as an alternate board member of the Green Grid, a nonprofit industry group that promotes environmentally friendly data centers, read the data furnace paper and is enthusiastic about the concept. Mr. Saunders is director of data center power initiatives at Intel, but spoke on behalf of the Green Grid.

“I’ve got a little house in the middle of the Oregon mountains.” he said. “I have baseboard electric heaters in it right now that cost me a fortune to run. What if I had a ‘baseboard data center’? It would just sit there and produce the same amount of heat with the same amount of electricity. But it would also do computing, such as decoding DNA, analyzing protein structures or finding a cure for cancer.”

I.B.M. Research-Zurich is designing water-cooled servers whose waste heat can be carried in pipes to nearby buildings. Next year, it plans to demonstrate the technology with SuperMUC, a supercomputer under construction in Munich that will be more powerful than 110,000 PCs.

Many cities in Europe already have insulated pipes in place for centralized “district heating.” Heat generated by data centers is beginning to be distributed to neighboring homes and commercial buildings — in Helsinki, for example. But for the rest of us, without such pipes near our homes, the computing would need to be done under our own roof to put the heat to good use.

If tech companies with data centers like the economics of home-based data furnaces, they could offer heating for homeowners at an irresistible price: free.