EVANSTON, Ill. — When it rained, water filled the basement a foot high, flooding the preschool room at least once a year. The air conditioner wouldn't work in two rooms at the same time. The Jewish Reconstructionist Congregation desperately needed a new synagogue.

As members planned their new building, they decided it should reflect the belief, shared by many faiths, that God calls them to be responsible stewards of the Earth.

They decided to go green from the ground up.

Cypress wood reclaimed from barns in upstate New York was used for the new synagogue's exterior, white cinder blocks from the old building were crushed and recycled, and brown cabinet doors made from sunflower husks were hung in the offices.

As Americans are becoming more environmentally conscious, more religious groups are looking to make their worship spaces sustainable. The efforts range from small country congregations using energy-efficient bulbs to megachurches complying with complex green-building codes.

"It was about making a sacred statement," Rabbi Brant Rosen said of the synagogue in Evanston, a Chicago suburb. "If we were going to talk the talk, we needed to walk the walk. The whole process forced us to look at our values in a deeper way."

The $9 million synagogue opened in February 2008 and in September became the only house of worship in the country to receive the highest green-building rating from the nonprofit U.S. Green Buildings Council, whose standards are considered the benchmark for environmentally friendly buildings.

Since 2005, just 10 congregations have received the council's certification for environmentally friendly buildings, called the Leadership Energy Environmental Design, or LEED, certification. Another 54 congregations have applied.

Among the applicants are seminaries, chapels, sanctuaries, monasteries, student centers and church offices. They are Jewish, Roman Catholic, Methodist, Mennonite, Presbyterian, Unitarian, Wesleyan and Lutheran.

"They believe that God calls them to become better environmental stewards and they see this as a way to express that," said the Rev. Fletcher Harper, chairman of Green Faith, an interfaith group in New Brunswick, N.J., dedicated to the environment. "And they want to make good and responsible use of their congregation's financial resources."

By going green, most worship buildings can cut their energy costs by 30 percent, said Jerry Lawson, of the Environmental Protection Agency's Energy Star Congregations program. About 2,000 of the nearly 310,000 houses of worship in the U.S. participate in the EPA program.

"That's a lot of money that can go back into the mission," he said. "Why waste the money the members of the congregation have donated to operate and maintain your building?"