Freddie Mac reports that residents of apartment communities that include five or more rental units currently make up 15 million U.S. households — a figure that is expected to climb with shifting demographics and housing preferences.

Such factors as demographic trends, household formations, and higher credit standards for home loans are driving the increase in rental housing, notes Freddie Mac senior vice president of multifamily David Brickman. At the same time, though, affordable rental housing is becoming more elusive in certain parts of the country because of gross rent, or rent plus resident-paid utilities.

More than half of all people who rent spend more than 30 percent of their income on housing — an increase from 40 percent in 2000. Low-income households tend to spend even larger portions of their incomes on rent, based on the U.S. Census Bureau’s American Community Survey 2000-2011.

Brickman asserts that Freddie Mac remains dedicated to supporting affordable rental housing. He concludes, “Working closely with multifamily property owner/borrowers and our network of lenders, Freddie Mac Multifamily structures financings in a way that lets us offer very competitive, long-term rates.