Rents for offices and apartments in America will rise faster than inflation over the next three to four years as the economy expands and mortgage rates increase, the billionaire real estate investor, Sam Zell, said.

Office rents may rise 7.5% a year on demand from companies adding employees, Mr. Zell, 64, said yesterday in an interview. Apartment rents may climb 6% to 7% annually as higher mortgage rates discourage people from buying properties.

“We’re in a situation right now where we’ve come through three years of low rents,” Mr. Zell, chairman of Equity Office Properties Trust and Equity Residential, both Chicago-based real estate investment trusts, said. “It’s going the other way as occupancy is in creasing across the country in response to a strong economy.”

Office vacancy rates nationwide averaged 12.6% in the first quarter, compared with 12.5% in the previous quarter and 14.2% a year earlier, according to Cushman & Wakefield. Midtown Manhattan and Midtown South had two of the lowest vacancy rates in the country, at 7.8% and 6.2%, respectively.