The Tides Network, a nationwide group of nonprofit organizations, recently opened the Thoreau Center for Sustainability, a green office center at 55 Exchange Pl. It's reportedly the first shared community and conference space for nonprofits in lower Manhattan and is among the first office spaces in New York City registered for LEED Commercial Interiors certification by the US Green Building Council.

The renovation of the Thoreau Center's space incorporated recycled building materials, non-toxic paints and energy efficient mechanical systems. The center employs clean renewable energy, nontoxic cleaning products and extensive recycling programs.

"Nonprofits have an especially hard time finding affordable office space," says China Brotsky, vice president at Tides and managing director of Tides Shared Spaces. "That's why we both create shared spaces for nonprofits and have a program for helping others start their own green nonprofit centers."