By Jennifer Easton Commercial office has always been a dominant space type among LEED-certified projects. While commercial buildings used to be concentrated in the new construction sector, the USGBC has seen a growing ubiquity of green building retrofits and renovation projects. At the end of last year, we announced that LEED-certified existing buildings began surpassing new construction projects. This shift indicates that the stigma that green buildings must be built new is disappearing—and with good reason. With landmark projects like the Empire State Building completing successful retrofits (the project saved $2.4 million in energy costs the year following its LEED…