TechPulse 360

Down deep, Microsoft believes Windows 7, its latest operating system, will be more energy efficient than its predecessor.

Laptop batteries will run longer and need less frequent recharging. Desktop machines will suck less electricity from the wall socket.

But trying to determine exactly how much power will be saved is a difficult question to answer. That’s because it depends a great deal on how computer makers design and build the new machines that run the OS, which is due out Oct. 22.

One laptop may be small and light, and sacrifice power savings for reduced size and weight. Another might be built for speed, with higher performance components and less concern about energy conservation.

That’s why “we don’t have that as part of our discussion today,” said Michael Angiulo, a Microsoft general manager who offered a technical briefing Tuesday in San Francisco on the software’s efficiency. Power savings will vary machine to machine.

Efficiency improvements and better life will depend on teh choices computer manufacturers make, says Microsoft's Michael Angiulo

Under the hood, Windows 7 does have some features that make it greener than its predecessor, Windows Vista.

One advance is called “timer coalescing,” which better schedules the work a processor does. Tasks are grouped and sent to a processor core simultaneously so the processor finishes jobs quicker and returns itself to a deep sleep. Microsoft worked on the technology with chipmaker Intel.

Better software management techniques also play a role. The management software allows a processor to be scaled up to higher energy states when that extra performance is needed and not before.

In one demo, a laptop running a DVD achieved 20 percent better battery life with Windows 7 than with Windows Vista.

Another demo showed Windows 7 booting in just 11 seconds, saving battery power in the process. “This shows what system manufacturers can do,” said Ruston Panabaker, principal program manager. The computer was built around a laboratory “reference design” from Intel and ran high performance hardware.

So how soon will commercially available PCs see the same startup speeds? The answer is not easy to know. “We’re not the people to answer that question,” said Angiulo. It depends on the OEMs.