The Bill & Melinda Gates Foundation is the Largest LEED Platinum Non-Profit Building in the World

The <a href="http://inhabitat.com/tag/bill-and-melinda-gates-foundation/">Bill &amp; Melinda Gates Foundation</a> is known for working diligently to improve lives around the world, but did you know its headquarters is also a paragon of sustainable design? The new campus in downtown Seattle was completed in March of 2011 and yesterday it was awarded with a <a href="http://www.usgbc.org/DisplayPage.aspx?CMSPageID=220" target="_blank">LEED-NC Platinum Certification</a>, making their 639,860 sq ft campus the largest certified non-profit building in the world. <a href="http://inhabitat.com/tag/nbbj">NBBJ</a> led the design team, who equipped the building with 2 acres of living roofs, 1 million gallons of rainwater storage, solar systems and a long list of sustainable design strategies.

The new campus occupies a site located in downtown Seattle across the street from the Space Needle. Formerly an asphalt parking lot, the site is restored with more than 40 percent of it turned into green space with 2 acres of living roofs and native landscaping around the buildings.

The campus is composed of two U-shaped buildings with a large open courtyard in between, surrounded by landscaping and green roofs.

“The project started seven years ago with the initial target of LEED Silver, in support of the City of Seattle’s green building mandate,” said Margaret Montgomery, principal and lead sustainable designer at <a href="http://www.nbbj.com/" target="_blank">NBBJ</a>.

To achieve LEED Platinum, the Foundation and its design team worked diligently to incorporate a number of <a href="http://www.gatesfoundation.org/500-Fifth/Pages/sustainability-of-our-new-campus.aspx" target="_blank">sustainable strategies into the project</a>.

Reduced energy usage was achieved by installing energy efficient mechanical systems and lighting, along with occupancy and daylighting sensors, use of natural ventilation and high performance glazing.

A 750-thousand gallon water storage system minimizes energy used to cool buildings by chilling stored water at night for recirculation during the day.

Additionally, 47 evacuated tube solar collectors on the roof provide hot water to the campus, reducing the energy use by 30% and saving 4,750 therms of natural gas every year. In total, the energy efficiency strategies reduce energy use by 40% and the upfront investment will pay for itself in 30 years.

Water conservation was also a top priority in order to protect the local watershed from further depletion and pollution. The two-acres of living roofs absorb and collect most of the rainwater runoff and the remainder is directed via the hardscaping and landscaping into the underground one-million gallon cistern.

Water efficient plumbing fixtures and the use of rainwater reduce the campus's potable water use by nearly 80 percent and eliminate all polluted rainwater runoff.

Recycled content materials and recycling efforts during construction also led to big payoffs for the campus. There was also a concerted effort to source materials locally and hire contractors from the area to boost the local economy.

“A sustainable campus was a natural result of the foundation’s overall philosophy, keeping in line with our values to be a good steward and be a positive addition to the neighborhood and the environment,” said Martha Choe, chief administrative officer for the <a href="http://www.gatesfoundation.org/Pages/home.aspx" target="_blank">Bill &amp; Melinda Gates Foundation</a>.