PAWTUCKET — The city’s mills were once notorious for discharging streams of pollutants into the Blackstone River, pouring toxic materials into the soil and groundwater, poisoning the atmosphere with noxious fumes.

So you wouldn’t think that a conference promoting environmentally friendly design principles would feel at home here.

Nor would you expect that such a conference would feature tours of the city’s industrial buildings and mills.

The 22nd Annual Rhode Island Statewide Historic Preservation Conference, scheduled for April 14, will do just that.

In addition to speeches by Jean Carroon and Ralph DiNola, two architects at the forefront of the sustainable design movement, the day-long conference, dubbed “Something Old, Something Green,” will feature a roundtable discussion on the “greenness” of historic preservation.

It will offer a forum on saving the remnants of the city’s historical architecture, a tour of factories that have been converted into condominiums, case studies on striking a balance between historic preservation and environmentalism, plus a discussion of the trend toward privatization of historic sites.

“I think part of what we’re doing in the conference is recognizing that the new design concepts of sustainability fit in very well with historic buildings,” said Edward F. “Ted” Sanderson, executive director of the Rhode Island Historical Preservation and Heritage Commission.

“Old buildings — the materials that the old buildings are made out of — represent a huge reservoir of stored energy,” he said.

“Sustainability” is a new buzzword among architects and planners. It not only emphasizes the use of clean power sources, such as geothermal wells and solar energy, it evaluates the building process from start to finish, making sure that none of the materials or techniques used cause environmental harm.

While the city’s jewelry factories and textile mills discharged tons of pollutants into the earth and atmosphere, they also harnessed water power, minimizing the use of the fossil fuels that some, including former Vice President Al Gore, say contribute to global warming.

The Bridge Mill Power Station, built in 1894, is one example, Sanderson said. Slater Mill is another.

Recently, the 214-year-old Slater Mill Historic Site received a $250,000 grant from the federal government, most of which is being used to explore the possibility of using an idle turbine to generate electricity, said Francine Murphy-Brillon, Slater Mill’s director of programs and marketing.

The Bridge Mill Power Station is being operated by Charles Rosenfield, a Connecticut businessman who has an agreement to use the hydroelectric equipment there, said Sarah Zurier, of the preservation commission.

The Bridge Mill Power Station and Slater Mill will both be featured during the preservation conference, Zurier said.

So will the city’s Oak Hill plat and its 20th-century architecture. Robert O. Jones, of the state Preservation Commission, and Paul C. Mowrey, of the Pawtucket Preservation Commission, will lead tours of both.

“This is definitely Rhode Island’s first preservation conference that is focusing on sustainability,” Zurier said. It is one of the first such conferences in the country, she said.

At least 500 people are expected to attend. Panel discussions will take place in the Pawtucket armory, which a nonprofit group has transformed into an arts high school and performing arts center. The closing reception will be held in the W.T. Grant building, the former department store at 250 Main St. that J. Hogue, a graphic artist, and Michael Lozano, a nonprofit real estate developer, have carved up into studios for designers and artists, and small businesses, such as cafes.

Both venues show that historic preservation is taking hold in the city, thanks in part to the availability of state historic tax credits, Sanderson said. The last time the annual preservation conference was held in Pawtucket, in 1996, neither building was available, he said. “I can remember 10 years ago scrambling around for places to meet.”

The conference costs $35 and includes coffee, lunch and the closing reception. For more information, visit the preservation commission’s Web site at www.preservation.ri.gov/conference, or contact Janet Balletto, conference coordinator, at (401) 732-1009.

jcastell@projo.com