North Philadelphia's Nicetown-Tioga section might not be the first place one associates with environmentally sensitive remodeling.

But the nuns who run the nonprofit Mercy Neighborhood Ministries of Philadelphia Inc. took up a "green" challenge there, completely transforming a crumbling five-building warehouse complex, circa 1930s, and creating living space as well as room to accommodate their social mission.

"We needed one central place from which to grow our many community-service programs, and in looking at our long-range strategic plans, rehabbing this property in the 1900 block of Venango Street made perfect sense," says Sister Ann Provost, the ministries' executive director.

"Going green was just an unexpected bonus."

Sister Ann and two other nuns, Sister Margery Lowry and Sister Cathy Manderfield, live in the eco-friendly 32,000-square-foot complex, where two of them also work full time. (Sister Cathy works in Old City, as a social worker for Women of Hope at Fourth and Vine Streets.)

Before the warehouse property was purchased in 2005, the nuns were living in and organizing their professional efforts from a nearby convent consisting of three rowhouses - a command center of sorts.

"In some ways, it was like a game of musical chairs in that we were always rearranging what limited space and furniture we had to accommodate our many outreach programs, not to mention board meetings," Sister Ann says, laughing.

But maintaining a presence in the community was paramount - and meant staying within a 12-block radius.

"We wanted to be sure that what we were doing would be positive for everyone," she says.

The resulting warehouse rehabilitation could not have happened without a full partnership and "buy-in" among Mercy Neighborhood Ministries, local residents, the business community, and area community groups, Sister Ann says.

Project architect David Brawer, of Brawer & Hauptman Architects, a longtime proponent of green technology and its benefits, was key in getting LEED (Leadership in Energy and Environmental Design) Silver certification.

"A major part of green technology involves modifying and adapting existing structures to suit specific needs, as opposed to just tearing them down and starting from scratch," Brawer says.

Reusing and recycling materials is a big part of that.

During an initial assessment of the site, for example, Brawer discovered five large skylights that had been tarred over. Now completely cleaned and refurbished, these glass panels allow an abundance of natural light to stream in, reducing the need for artificial illumination.

Roof monitors, along with large fabric overhead tubes called DuctSox, help distribute airflow more evenly and stabilize indoor temperatures.

Additional site analysis revealed that Mercy Neighborhood Ministries' actual space usage would be less than the total footprint of the complex.

As a result, some of the unused square footage was converted into spacious, well-lit open courtyards, where people can relax and children can play safely.

Among the green steps taken during the construction phase of the rehab:

Large, inefficient industrial windows were replaced with energy-efficient substitutes.

Motion-detector switches and energy-efficient light fixtures were installed.

State-of-the-art heat-recovery systems were put in.

A white roof was installed, which reflects heat instead of absorbing it.

Upstairs living quarters and staff rooms boast several Energy Star-rated appliances, which means they use at least 10 percent less energy to operate than standard appliances require.

Bathrooms have automatic sink faucets that detect hand motion and regulate water flow. Toilets use less than a gallon of water per flush.

Outside the main entrance, a former asphalt-and-concrete parking lot - once overgrown with weeds and strewn with trash - has been transformed into a retreat with a wide variety of shrubs, flowers, and other plantings.

The picturesque garden, whose beauty is the result of Sister Margery's green thumb, has a birdbath, making it suitable for designation as a bird habitat by the Audubon Society.

"Living in a green building reminds you that you're part of a something much bigger," observes Sister Cathy.

"Going green is really a state of mind," she says, "shifting to a holistic approach to living and giving back to both the environment and the community in which you live and work."