Institutional owners of office buildings continued to pursue green building certifications in the 30 largest U.S. markets during 2015. Continuing an upward trend over the past decade, green certifications are now held by 11.8 percent of all surveyed buildings, representing 40.2 percent of all office space. Both figures are slightly above last year’s results, according to the third annual Green Building Adoption Index study by CBRE Group, Inc. and Maastricht University. “Green” office buildings in the U.S. are defined as those that hold either an EPA ENERGY STAR label, USGBC LEED certification or both.