Two historic mill buildings have been converted into 75 units of mixed-income housing in Lawrence, Mass.

WinnDevelopment, the real estate development arm of WinnCompanies, put the long vacant buildings back into use with the recent opening of Loft Five50.

“We hope that our investment and our development will make a ripple to cause more development of the mills,” said Adam Stein, vice president of development.

The lofts are a big step in restoring one of the most prominent and historic sites in Lawrence. The property is part of the 29-acre fleece factory that is now home to the Polartec brand.

The textile mill was operated by three generations of the Feuerstein family. In 1995, a fire destroyed three buildings, displacing 1,400 workers. Owner Aaron Feuerstein, who was dubbed “the Mensch who saved Christmas,” continued to pay his workers for months, gaining national attention as an example of a corporate leader who put his workers first.

Despite a $450 million rebuilding effort that was completed in 1997, Malden Mills went bankrupt, and the property sold in 2007 to Versa Capital, which purchased the assets to create a new company, Polartec, LLC.

Winn, which had been at work on its development for years, purchased its two buildings from Versa Capital in July 2011.

One of the challenges was preserving the historic nature of the buildings while creating contemporary, energy-efficient lofts. The team found ways to strike a balance, including providing exposed brick walls in the living rooms but insulating the bedroom walls.

The approximately $30 million development used several financing sources, including about $9.7 million of state and federal historic tax credits and $4.8 million of state and federal low-income housing tax credits. The rest came from private financing and equity investments from WNC & Associates, which syndicated all the tax credits. Nationwide Insurance was a key investor in the federal credits.

Eighty-five percent of the apartments are reserved for residents earning at or below 60 percent of the area median income (AMI), 10 percent of the apartments are for residents earning no more than 30 percent of the AMI, and the remaining 5 percent of the units are unrestricted, allowing for market-rate residents.

Winn, which is considering a second phase of apartments at the site, has completed 17 historic mill redevelopments in recent years.