WASHINGTON — It started a little more than a year ago, with an innocuous question during coffee hour after a Sunday service at Grace Episcopal Church in Silver Spring, Maryland. The Rev. Andrew Walter remembers someone asking why the congregants were using paper plates and cups at their weekly gathering. Wasn’t there a greener alternative?

The small matter was resolved quickly, Walter said, “and then people kept asking, ‘What else can we do?’ ”

During the next 15 months – as the church installed LED lights in the fellowship hall, low-flow toilets in the restrooms and a new energy-and-money-saving HVAC system – Grace Episcopal Church joined the faith communities across the nation that are increasingly embracing environmental activism.

Faced with an ever-growing array of faith-driven environmental programs at the national, local and denominational levels, Grace Episcopal Church became the third congregation in the Washington area to enroll in a two-year certification program through Greenfaith, an interfaith environmental organization based in Highland Park, N.J. The ambitious program felt like the right fit, Walter said, because it involved all aspects of the community’s life, everything from “greening” the building to changing the way the parishioners navigate their daily lives.

When Greenfaith was founded in 1992, it was a small partnership between Jewish and Christian leaders in New Jersey, with just a handful of faith communities involved. Now the organization works with more than 4,000 congregations of many faiths across the nation, and 75 of those are a part of the two-year certification program specifically, said Stacey Kennealy, director of the Greenfaith certification program.

Participation in Greenfaith’s programs began to surge in earnest about five years ago, Kennealy said. Before that, “We had to do a lot of educating about why people … of faith should care and take action on this,” she said. “We had to do a lot of convincing.”

Since then, she said, “it’s switched pretty dramatically. There’s more talk of climate change, and the reality of climate change is accepted more readily by congregations.”

Greenfaith’s two-year certification process is the most comprehensive of the organization’s programs, requiring that congregations include their environmental efforts in worship services, buildings and grounds, and communities.

“It’s not for the faint of heart,” Kennealy said of the program. “But for those who are willing to commit the time and the energy to it, it has a huge impact on their environmental footprint, and it really greens their community from top to bottom.”