The term "green architecture" usually is associated with sleek new buildings that employ the latest innovations in recycled materials, energy efficiency and environmentally conscious design. But the fact remains that new construction covers only a small number of the estimated 4.5 million commercial structures in the United States.
So when one of the world's largest wholesale commercial buildings -- the venerable Merchandise Mart in Chicago -- underwent a massive, multistage conversion that won it a coveted environmental certification, many people took notice.