CHAPEL HILL - Five years after it began with what architect Mark Rylander called the idea of creating "a building like a tree," and several months after the first residents actually moved in, the innovative Greenbridge development on the western edge of downtown officially opened Friday.

Greenbridge founder Tim Toben cut a yellow ribbon in front of a small crowd of project partners, dignitaries and residents to mark the grand opening of the $56 million, 10-story condominium and mixed-use project on West Rosemary Street.

Some town leaders say the environmentally progressive project is the shape of Chapel Hill to come. They call Greenbridge - with its advanced green design and construction and its location within walking distance of UNC, the 100 block of Franklin Street and downtown Carrboro - an essential step in the revitalization of downtown.

"We think this is a game-changer," said Jim Norton, executive director of the Downtown Partnership, a nonprofit organization that promotes economic development in the central business district. "It's a wonderful, wonderful anchor for the western edge of downtown, and its residential component is so important. We think this is the future of our community."

Greenbridge is the first mixed-use project in North Carolina to earn the Leadership in Energy and Environmental Design (LEED) Gold certification. Its green features include solar energy, water conservation and energy-reduction systems.

"It's gratifying to see this building so beautifully executed, and so close to our vision," said Rylander, an architect with William McDonough + Partners, which designed the project. "We asked ourselves, 'How can a building be like a tree?' Here, where the parking is underground next to great cisterns that collect rainwater, where solar panels soak up the sunlight, and where light pours through the windows and onto the courtyard, we see a building that truly is like a tree."

The building includes 97 condominium units, most of which have been bought, and 36,000 square feet of retail and office space. While the market-rate condos range in price from $259,000 to nearly $1.5 million, 15 units are priced under $100,000, affordable units mandated by town guidelines and sold through a collaboration with the Community Home Trust.

"This is a terrific opportunity," said Robert Dowling, executive director of Community Home Trust. "Many of the people who have bought these are young single people who work at UNC and can walk or bike almost everywhere they go. We sold these units and the ones at East 54 much faster than I expected."

Thirteen of the 15 affordable units at Greenbridge have closed, and the other two are due to close soon.

"I absolutely love it," said Nancy Fantozzi, a student and consultant who moved into one of the affordable units in June. "There's a great sense of community already. One of the most impressive things to me is that nobody makes any distinction between the market-rate buyers and the affordable buyers."

Greenbridge hasn't gone without detractors during its years of planning and construction. Opponents have said the project's towers are out of scale with the surrounding area and threaten the historically minority neighborhood of Northside with gentrification.

There were no discouraging words at Friday's ribbon-cutting, though. The closest thing to a naysayer in evidence was Will Raymond, a former Town Council candidate who said he sees signs of the gentrification he and others warned of.

"You're starting to see some impacts on minority businesses in the area, and I think you're starting to see developers cast their eyes toward Northside," Raymond said. "I think we should learn a lot of lessons from Greenbridge for the next big project we build."

But the prevailing view Friday was that of Aaron Nelson, president and CEO of the Chapel Hill-Carrboro Chamber of Commerce.

"We see right here the renaissance of downtown," he said. "You're helping make Chapel Hill the place where I want to live - a place where you can live, work, shop, eat, raise children, and you can do it all right here in downtown Chapel Hill."