NEWS

PITTSBURGH (NYTIMES.COM).- In a contemporary retelling of Aesop’s fable of the tortoise and the hare, Pittsburgh is finding recession-era advantages in a slow-growth legacy.

The 1915 Union Trust Building in Pittsburgh, with its rotunda capped by a stained-glass dome, has been given an energy-conserving renovation.

The city, which has lost half its population since 1950, had a well-chronicled change of character over the second half of the 20th century: from a center of the steel industry to headquarters for many large corporations to a much more diverse economy that encompasses health care, education, finance and technology.

As it shrank, the city had relatively little new construction compared with many United States cities. But it was in the forefront of the movement to conserve existing structures and clean up the contaminated industrial sites called brownfields, becoming a leader in the field of sustainable building. That is now serving Pittsburgh well during the economic downturn.

Describing the area’s rebuilt economy, the Allegheny County executive, Dan Onorato, said: “It’s clean, it’s shiny, it’s green. Slow, steady growth is our strongest asset.”

The city’s commercial real estate market is relatively healthy. In the fourth quarter of 2008, Pittsburgh earned the top ranking in Moody’s Investors Service’s quarterly “Red-Yellow-Green” report on the state of commercial real estate in 60 major United States cities.

Though the southwestern Pennsylvania metropolitan area is only the 22nd largest in the United States in terms of population, the city employed energy-efficient construction well ahead of larger cities. In 2005, Pittsburgh claimed more LEED-certified square footage — meaning it had met Leadership in Energy and Design standards for energy-saving designs and building techniques — than anywhere else in the United States. As other cities have caught up, Pittsburgh now ranks seventh nationally in the number of buildings with such certification, according to the local Green Building Alliance.

Founded in 1993, the alliance says it is the first nonprofit organization in the nation to encourage green commercial building. “There was no government-driven agenda here,” said Rebecca Flora, former director of the Green Building Alliance and now senior vice president of education and research at the national Green Building Council, a nonprofit organization that oversees the LEED program. “Pittsburgh’s doing green in a weak market city with existing building stock, and it’s done it without government programs.”

A number of century-old landmarks have been revived as energy-efficient buildings in the last decade, and several major projects, both new and retrofits, will open this spring.

Years before national environmental building standards were set in 2000, Pittsburgh began experimenting in sustainability as local architects, engineers and academics debated how to reuse old industrial sites.

“We were working on the Model T of green building," said the architect Bob Kobet of the discussions among early proponents of solar energy, weatherization and nontoxic design.

With innovations that would later become widely accepted, like a rooftop garden and photovoltaic roof panels, the local Green Building Alliance’s first project, in 1998, retrofitted a 100-year-old former soap factory and art gallery as office space for Conservation Consultants Inc. “Nonprofits became the test market,” said Ms. Flora, with local foundations underwriting new designs.

Working with advisers from Carnegie Mellon University and the University of Pittsburgh, the alliance also provided technical advice for more complex renovations for other nonprofit groups.

In 1999, for example, Phipps Conservatory, a Victorian landmark at the entrance to a city park, began planning an energy-efficient expansion to blend with the century-old structure. A local architecture firm, IKM, preserved its signature fritted-glass dome with a $5.2 million below-grade welcome center. A 12,000-square-foot tropical forest exhibit deploys a radical roof venting system and geothermal tubes for passive cooling in a $7.5 million glasshouse. A solid-oxide fuel cell produces electricity from natural gas.

Two other public venues — the Children’s Museum of Pittsburgh and the David L. Lawrence Convention Center — incorporated energy efficiency in ambitious redesigns. The 1.5-million-square-foot convention center, designed by Rafael Viñoly in 1999, was completed in 2003. Its swooping riverfront design uses natural ventilation and illuminates a exhibition hall entirely through its windows and skylights.

The Children’s Museum sought to blend a historic 1897 post office with a 1939 planetarium that had stood vacant since 1991. The solution — a glass lantern shape that appears to float between the grand older structures — reused original materials, like terrazzo, marble and copper. In 2006, the design won awards from the National Trust for Historic Preservation and the American Institute of Architects.

Gary Saulson, director of corporate real estate for the PNC Financial Services Group, the nation’s fifth-largest bank, was a green building skeptic until 1998. Steel girders were already rising along the Monongahela River for Firstside Center, the bank’s 650,000-square-foot operations center, when Ms. Flora met with Mr. Saulson to suggest making the structure a sustainable building.

“At the end of the meeting, I had committed to make Firstside into a green building,” Mr. Saulson said. “It seemed like the right thing to do. As a company, we embrace new ideas and innovation.”