The housing market may be sputtering, but Habitat for Humanity International is getting a $100 million gift from an Atlanta businessman who built his fortune developing real estate and is now giving it away piece-by-piece to support affordable housing.

The nonprofit group announced Thursday it received the largest individual contribution in its history, an offering that will help Habitat build 60,000 homes around the globe.

It's one of the largest gifts in recent years to a group devoted to social services, according to the Center on Philanthropy at Indiana University. Dwight Burlingame, the center's associate executive director called it "remarkable" — especially in the midst of a gloomy economy.

The donation comes from J. Ronald Terwilliger of Atlanta, a former chief executive of housing developer Trammell Crow Residential Co. and a longtime member of Habitat's board of directors.

Terwilliger said through his work with Habitat and in the private sector he's witnessed poverty and seen people living in cardboard shacks and filth, as well as the struggle of middle-class families to find affordable housing.

"People need a decent, safe, clean residence where they can get a good night's sleep and families can be together," he said. "If they have that as an anchor, they have a way to send their kids off to school regularly and a better chance those children will be healthy."

The donation comes at a difficult time for the Americus, Ga.-based organization, which like other nonprofit groups has struggled with increasing demand and slowing donations amid the economic downturn.

"This is a chance to have a really deep impact," said Jonathan Reckford, Habitat's chief executive.

Habitat will use $30 million to fund an endowment that will make yearly grants to help build more houses. The remaining $70 million will set up a micro-finance fund to help low-income families around the world repair and improve their housing.

The micro-finance fund will provide loans ranging from several hundred dollars to several thousand dollars to some of the world's neediest.

Terwilliger, who graduated from the U.S. Naval Academy, became Trammell Crow's chief executive in 1986 and has long contributed to affordable housing projects. He also owns Atlanta's WNBA franchise, the Atlanta Dream.

He joined Habitat's board of directors in 2000 and was elected chairman in 2007. After stepping down as Trammell Crow's chief executive last year he devoted more time to traveling the world to witness Habitat's work. He remains the company's chairman.

Terwilliger has traced his interest in affordable housing to his post with the Atlanta Neighborhood Development Partnership in the mid-1990s.

While there, he saw the plight of middle class workers — firefighters, teachers, nurses — forced to live far from their workplaces because of high housing costs.

"People are often so far away from where they work that they have these tremendous expenses," he said. "It's an emotional drain, it's a health drain and it's a family drain."

Since then, he's given millions to affordable housing programs outside Habitat as well, including a $5 million gift to the Urban Land Institute.

His work helps show that traditional developers can partner with nonprofits to promote affordable housing, said Pam Patenaude, executive director of the institute's Terwilliger Center for Workforce Housing.

"He knows the developers alone can't make the numbers work," she said. "And being a finance guy, he started to realize no matter how much you want to be in affordable housing, unless you have tax credits, the need was huge and the federal subsidy was very limited."

Terwilliger called it a "moral imperative" to offer families more access to decent, affordable homes. And the short-term loan program he is helping to fund will make a lasting impression on the housing market by helping thousands of needy families, he said.

"We can provide additional solutions to families that need to build an extra room, that need to renovate their home," he said.

As he looks to disperse his wealth, Terwilliger said he's giving most of his contributions to housing charities. That includes a previous $3 million contribution to Habitat that helped fund a new administrative center in Atlanta.

He hopes his latest contribution will send a message to other philanthropists to step up their giving despite the troubled economy.

"My attitude is, for those of us who are fortunate enough to have made enough money that we don't feel we have to leave it all to our family, then we ought to give it back."