CHICAGO—Renters across the nation have made it clear they want more opportunities to live in environmentally-sustainable apartments, and developers have responded. That was one of the conclusions of a new study just conducted by apartment search website RENTCafé using data from its sister company Yardi Matrix, an apartment market intelligence provider.

RENTCafé dug into Yardi's national inventory of more than 14 million apartment units located in large rental buildings of 50 units or more, in 123 US metros, and found that 44,800 new green units opened in 2015 in large-scale developments, 13 times more than there were in 2008. In 2016, about 30,000 were open or under construction as of mid-year, and RENTCafé projects that developers will complete a total of about 59,000 green-certified apartments by the end of this year, four times as many as five years ago. RENTCafé defined “green buildings” as multi-family projects LEED-certified by the US Green Building Council or proposed for LEED certification.

Chicago topped the list with 13,800 green apartments, according to the Yardi data, but other cities, such as Seattle, which has a total of 11,200 green units in 87 residential buildings, have more green apartments on a per capita basis. In fact, 27% of the new construction in Seattle since 2009 is considered green. The city had 61 residents for each green apartment, the best ratio in the US except for Cambridge, MA, which topped the list with just 39 people for each green unit.