"It’s official — the Empire State Building has been awarded LEED Gold certification. Thanks to a massive green overhaul that took more than two years, the landmark is now the tallest building in the United States to receive LEED certification. "

"The groundbreaking retrofit included replacing the aging building’s windows with double hung operable windows and installing an energy efficient heating and cooling system. The changes are expected to reduce the building’s energy consumption by more than 38 percent and should save $4.4 million in energy costs."

Jessica Dailey reports for Inhabitat New York City September 14, 2011. [2]