One of this city’s most famous 19th-century mansions soon will benefit from 21st-century green-energy technology.

An extensive geothermal climate-control system is being installed at Marble House, a National Historic Landmark museum toured by nearly 150,000 visitors every year. The system will maintain steady, mild temperatures and a humidity level of 50 percent inside the house, helping to protect its contents, especially textiles, leather, paintings, paper and wooden objects. Another important benefit will be fuel oil savings of up to 80 percent, which reduces the building’s carbon footprint.

“Geothermal is a winning investment for our properties,” said Trudy Coxe, CEO and Executive Director of The Preservation Society of Newport County, which owns Marble House and nine other historic house museums. “These systems are expensive – the estimate for the Marble House project is $1.5 million. But we are committed to reducing carbon and caring for our houses in a sustainable way, and the long-term benefits make the investment well worthwhile.”

This is the fifth geothermal installation by the Preservation Society. Similar installations have been successful at Chepstow (installed in 2015), The Elms Carriage House (2016), The Breakers (2018) and Chateau-sur-Mer (2024).

Geothermal climate control draws upon the Earth’s year-round subsurface temperature of about 55 degrees to warm the house in winter and cool it in summer. At Marble House, contractors have drilled 21 wells, each 425 feet deep, in the expansive backyard. A series of tubes will circulate water into the wells, where the liquid will be cooled or warmed to the underground temperature. The water will then be piped into the house to regulate the interior temperature through a system of electric heat pumps and air handlers.

The Preservation Society expects to complete the project in the late spring of 2026. The major contractors are Donovan & Sons, JAM Construction and Shamrock Electric, all of Middletown.

The Preservation Society of Newport County, Rhode Island, is a nonprofit organization accredited by the American Alliance of Museums. It is dedicated to preserving and interpreting the area's historic architecture, landscapes, decorative arts and social history. Its 11 historic properties – seven of them National Historic Landmarks – span more than 250 years of American architectural and social development.

For more information, please visit www.NewportMansions.org.