Seattle - Ms Martha Choe's ideal working space is not her private office but a long table in the vast atrium of the Bill & Melinda Gates Foundation headquarters here.

The table, situated on a 10m-high open mezzanine, enjoys great swaths of daylight through the atrium's 10,890 sq ft of glass and has a stunning view of the Space Needle three blocks away. It is not private but Ms Choe has everything she needs in her laptop and she finds the space inspirational.

Ms Choe, a former member of Seattle's City Council, is the foundation's chief administrative officer. She had considerable input in the building's design.

One objective from the start was to give the 1,000 employees a variety of spaces to accommodate different kinds of work. 'There's a recognition that we work in different modes and we've designed spaces to accommodate them,' she says.

The building was designed by NBBJ, a 700- employee architecture firm whose largest operation is in Seattle. The structure is a culmination of ideas about the 21st-century workplace that NBBJ has been exploring in corporate office designs worldwide, including its own offices here.

These are the main concepts: Buzz - conversational noise and commotion - is good. Private offices and expressions of hierarchy are of debatable value. Less space per worker may be inevitable for cost-effectiveness but it can enhance the working environment. Daylight - lots of it - is indispensable. Chance encounters yield creative energy. And mobility is essential.

Seattle serves as a test tube because of several factors: There is a lot of money here to experiment with projects. The workforce is young and open to innovation. And the local culture places a high value on informality, autonomy and egalitarianism.

NBBJ occupies two 38,000 sq ft floors of a mid-rise office building it designed in 2006. There is not a private office or cubicle anywhere and there is constant low- level hubbub: people in motion and gathering into small groups.

NBBJ architect Brent Rogers says: 'If someone's wanting privacy, they're sending out signals that tell you. You become more sensitive to body language in an open-office environment.'

But Susan Cain, author of Quiet: The Power Of Introverts In A World That Can't Stop Talking, is sceptical of open-office environments - for introverts and extroverts alike, though she says the first group suffers much more amid noise and bustle.

She also says humans have a fundamental need to claim space: 'It's the room of one's own.'

The Gates Foundation's campus addresses some of these concerns. There is a mix of 60 per cent open and 40 per cent closed offices, with a variety of 'retreat' spaces that enable different personalities to find the work environments they need.

The campus occupies 522,720 sq ft of prime real estate next to the site of the 1962 Seattle World's Fair. It includes two boomerang-shaped buildings dressed in glass and European limestone and a vast courtyard with sculptures and water gardens.

Mr Steve McConnell, managing partner at NBBJ, says the boomerangs' transparency is their key quality. Gates employees often travel the world and research shows that exposure to daylight cycles helps people recover faster from jet lag.

Stairwells are positioned to land at hubs with coffee stations, copy machines and informal furniture groupings, so that employees from disparate departments can enjoy random meetings.

Everyone's laptop is equipped with a Microsoft platform that enables instant messaging, phone- and video-conferencing and people-finding tools.

A sampling of employee opinion shows that people use and appreciate the options. 'Maybe just moving from your usual space into another place that's really interesting... changes your perspectives of what's possible,' says Mr Alan White, deputy director of operations management in the foundation's United States programme.