Microsoft is in the midst of a massive expansion to its Seattle area campus and has a new strategy for the design of its buildings that reflects the software giant's changing business.

"It's not just Office and Windows anymore," said Martha Clarkson, a designer on Microsoft's staff who spearheaded the new direction.

Microsoft has decided to put more thought into the design of its buildings to reflect new businesses, such as the consumer-focused Xbox and Zune groups. It hopes that the added cost required to create the new look, which features open lobbies, colorful carpets and mod furniture, will pay off in productivity gains.

"We used to build generic buildings," said Chris Owens, general manager for real estate and facilities at Microsoft. Going forward, managers of businesses that will be in the buildings will have a say in the way the interior is laid out in order to support their business objectives, he said.

The new options are the result of a project that Clarkson undertook. She and her colleagues traveled to 26 Microsoft facilities around the globe, interviewing executives and studying the way employees work.

Some of their findings were surprising. For example, while employees estimated that they spent 75 percent of their work time in their offices, in reality they were in their offices only 41 percent of their time. The rest was spent in meetings or working from home, Clarkson said.

Clarkson and her team also discovered that even though Microsoft has a positive reputation for a policy that allows the majority of workers to have their own offices rather than cubicles, some teams prefer an open, collaborative work environment, she said.

Building 99, the first building created from the ground up to reflect the new design environment at Microsoft, has plenty of space for on-the-fly collaboration. The building, which officially opened Nov. 12, houses Microsoft Research and contains many small meeting rooms with comfortable chairs that workers can relax into and discuss ideas.

"We want serendipitous meetings," said Kevin Schofield, general manager for Microsoft Research. He wanted an open design that lets people see each other across the building or in another room and allows them opportunities to grab a nearby space to sit down and discuss ideas.

One group in particular should like the new available spaces. The theory group within Microsoft Research includes physicists, economists and mathematicians. They meet for afternoon tea every day, Schofield said. It's a social get together, but they gravitate into conversations that end up relevant to their work, he said. In their old building, they met in nondescript conference rooms that might not have windows or a white board.

In building 99, they'll be spoiled for choice of comfortable rooms to have their tea. Some rooms can't be reserved, so that they're more likely to be available for spur-of-the-moment meetings. Many have comfortable chairs surrounding a coffee table, more like a sitting room in a home than an office conference room. Also, most of them feature glass walls that workers can treat like white boards, writing diagrams or ideas on them and then erasing the drawings.

The building features a central atrium in the lobby topped with a glass roof and with conference rooms overlooking the space. Open staircases flank the atrium, which has a cafi in its center. The space was built to be able to accommodate a meeting of all 650 people who work in the building and all future buildings on campus will have a similar feature.

Schofield used a relatively new Workplace Advantage Lab on campus to see the ideas that Clarkson's team had come up with and choose what would work best for the group. The lab shows off options such as offices with moveable walls that can be converted into larger, shared office spaces and conference rooms that are flanked by offices.

Sliding doors will be one feature that will come standard in all office buildings, as opposed to hinged doors that take up more space. Also, lights in offices will have sensors so they turn on when someone walks into the room and off when the room is empty. All new buildings will also feature under-floor cooling systems, which save energy because they blow cool air from the ground up, rather than forcing cool air from the ceiling through warmer air that naturally rises.

The new office design is more expensive than the old way of doing things, said Owen. But when 90 percent of the cost of running a building is paying for the people inside of it, it's easy to pay off investments that drive productivity, he said.

Microsoft, which already employs over 36,000 people in the Puget Sound region, continues to grow at a fast rate. Last year, the company said it would spend $1 billion on a three-year campus expansion plan. But in mid-November this year it said it would add five more buildings to the previous plan, so now the expansion will support 19,000 new workers. The new plan includes an area of campus planned for completion in early 2009 that features a central outdoor commons, a post office, mini-spa, bookstore and 12 food venues.