Roughly one-third of the U.S. population lives in the country’s 500,000 multifamily buildings, and they spend $22 billion on energy every year. Until this year, apartment and condo managers lacked the tools to measure how much energy they were wasting and compare their performance nationwide. Meanwhile, energy costs for renters have risen by 20 percent over the past decade. Today, a new era of savings will be ushered in when the U.S EPA announces the first set of multifamily properties to earn the ENERGY STAR certification. The ENERGY STAR first became available to the sector this September, after a three-year partnership with Fannie Mae to develop the scoring system for multifamily properties.