The Wing Wo Tai building on Nu'uanu Avenue is a distinctive piece of 19th-century Honolulu. It's been there since the days of horse-drawn buggies.

But the quaint exterior of the 132-year-old building, home to The Nature Conservancy, masks a cutting-edge renovation project that transformed it into the greenest existing building in Hawai'i.

It draws power from the sun, uses plumbing that reduces water use by 30 percent and hosts so many eco-friendly practices that the U.S. Green Building Council recently gave it the first Leadership in Energy and Environmental Design certification for an existing Hawai'i building.

That coveted stamp of approval is the gold standard for high-performance green buildings. Certifications are more commonly given to newer buildings. Only 307 older buildings worldwide have earned that recognition.

"It makes us feel great about the kind of organization we are," said Suzanne Case, executive director of the conservancy's Hawai'i office. "All of our staff are very excited about it. ... We are eager to share what we learned with other businesses."

OFFICE MANAGEMENT GOES GREEN, TOO

The project took two years and cost about $310,000. A large chunk of that — about $100,000 — was for the photovoltaic system on the roof, which produces electricity from the sun. It was paid for and is owned by two companies that sell solar power to the conservancy.

"We're still paying for electricity, but we are paying for green electricity," Case said.

A new air conditioner for the building cost the conservancy $160,000, but the purchase was necessary because the old one was giving out.

"Lucky for us, our system was dying and we had to replace it anyway," she said. "Our system just wasn't at all efficient. We were wasting a lot electricity trying to pump cool air into the building."

In creating a green building, the conservancy adopted a new set of office management practices.

It began using recycled paper in all its printers and copiers, unbleached paper for its newsletter, recycled printer cartridges and toilet paper made from recycled paper. It bought power strips and computers that saved on energy.

The conservation group also increased its own recycling efforts. It hired a janitorial service that uses green cleaning products and when it came to replacing existing furniture, it found a company that would recycle what it was throwing out.

Even the sign on the door is made of recycled material.

"You just don't throw everything away," Case said. "You try to be cradle-to-grave about it. You try to make sure you are approaching it in a sustainable, reduce, reuse, recycle manner as much as possible."

ANY BUILDING WILL DO

The building's age did not create problems, said Malek Yalcintas of Amel Technologies Inc., who designed the air-conditioning system.

"This can be done on any building," she said. "As long as the building occupants or owners are committed and the building employees are committed, you can do this to any building."

The need for projects like this has never been greater, Yalcintas said. Efficient engineering means less of a demand on burning fossil fuel and the result is a cleaner environment, she said.

"Energy efficiency is very, very critical for our time, not just because energy prices are high but because we are releasing so much polluting carbon dioxide, which is causing global warming," Yalcintas said.

Because older buildings dominate the landscape, they present the greatest potential for reducing the overall carbon footprint of communities.

"You could adopt a lot of ideas that are a great step in the green direction," Case said. "If every business changed practices like these, we could make a huge difference in the world."

Suzanne Case tells how The Nature Conservancy made its historic Chinatown building more energy-efficient, at