Nov. 1--Growing up in the southwest suburbs, Sara Beardsley had a view of the Chicago skyline from her house. Today, she is transforming that skyline, but you won't find her work glorified on a $6 mug or gracing postcards.

Most of her impact is invisible as she attempts to reduce one of the largest carbon footprints in Chicago -- that of Willis Tower. Beardsley, a senior architect at Adrian Smith + Gordon Gill Architecture in Chicago, is managing a $200 million to $300 million project to "green" the tallest building in the Western Hemisphere.

The building was completed as Sears Tower in 1973, the heyday of energy ignorance, which means the skyscraper has single-pane windows that leak around the edges and let in hot air in summer and cold in winter, lights everywhere and inefficient electric heating throughout.

"Each old window is like a car driving around," Beardsley said. "And people don't think of it that way -- it's just a window. But I think maybe we need to start thinking about it that way."

Buildings account for about 70 percent of all Chicago emissions, according to the Chicago Climate Action Plan. If the largest 10 buildings in the Loop were targeted for greening projects, Beardsley said, it would reduce the energy needs of the Loop by more than 10 percent.

In particular, mid-century buildings can average as much as double the energy load of modern buildings and 10 times that of the newest, most energy-efficient buildings, she said. Willis Tower uses enough electricity each year to power 9,000 Chicago homes, despite changes over the years that have reduced the energy load to about 1.5 times a new office building.

With a building as enormous as Willis Tower, the floor space of which is equivalent to 16 city blocks, a change in the direction of the sun can mean that when the temperature outside is 5 degrees, air conditioning is being pumped into one part of the building because so much heat is being collected from the sunlight while the side in shadow is being heated. An experimental green roof (greenery planted on a roof to lower energy costs and offset water runoff) on the 90th floor required metal meshing to prevent sod and plants from blowing away.

"The scale of this is mind numbing," said Nathan Kipnis, principal of Nathan Kipnis Architects Inc., a firm specializing in green and sustainable architecture. Kipnis was one of several curious architects and engineers who attended a presentation about the project (held on the 99th floor) originally meant for city docents but later expanded because of interest from the architectural community.

On its face, Kipnis said, greening a building like Willis is like greening any other building -- you look at what goes in and what comes out. But the complicating factors are magnified and the issues are unique.

"Just think of what it takes just to get the food up here," he said.