Hit by rising joblessness and cutbacks in business spending, commercial construction in the U.S. is set to decline 16% this year, followed by a 12% fall in 2010, the American Institute of Architects said. "Why do you build new office buildings? You need to see job numbers pick up," said Kermit Baker, the institute's chief economist. "Why do you build new retail centers? You need to see consumer spending pick up."