SAN DIEGO, CA — Researchers at U.C. San Diego have developed a new software program that uses lightweight virtual instances of sleeping PCs to provide simple functionality while cutting energy use by 60 to 75 percent.

SleepServer, the creation of Yuvraj Agarwal and his research team at the Department of Computer Science and Engineering, is the follow on to his previous project, Somniloquy, which developed the concept of drowsy computing to let PCs operate to a limited extent while idling in a lower energy-use mode.

SleepServer takes the developments of Somniloquy to the next level. Without needing a separate piece of hardware like the older technology required, SleepServer can, in a sense, keep the lights on while doing very little work. With SleepServer enabled, computers can respond to requests from programs like network administration and updates, instant messaging applications, and VOIP calls.

When a request arrives that the virtual PC instance has not been configured to handle, only then does the machine fully wake up.

"Our goal with SleepServer is to help buildings with heavy IT-loads reach net-zero energy use," Agarwal said, "so that these buildings effectively become carbon neutral by generating as much renewable energy as they consume."

Agarwal has measured the energy used by his own computer with SleepServer installed, and found a 70 percent reduction in energy use. The head of Agarwal's department at UCSD sees big potential in the software as well.

"According to our measurements, SleepServer provides $60 dollars of cost savings per PC on average over an entire year," said Rajesh Gupta, Professor and Chair of the Department of Computer Science and Engineering at the UC San Diego Jacobs School of Engineering. "By deploying SleepServer across the CSE Department, we expect to save approximately $60,000 dollars annually in direct energy costs alone."

The figure below shows how SleepServer can impact energy used by computers that would otherwise be left running 24/7 (a larger version of the figure is available here): 

The school plans a department-wide rollout this year, covering about 1,000 computers; the next phase of the test is to spread it across the entire U.C. San Diego campus.

_{Photo CC-licensed by Flickr user djenan.}