Cooling Trend Predicted for Mount Vernon

Mount Vernon, one of the hottest attractions--literally--in the Washington, D.C., area, is about to get a cooling off. Air-conditioning is finally coming to George and Martha Washington’s 18th century mansion.

This is bound to be glad tidings to the million or so tourists who flock to the 500-acre historical site in Fairfax County, Va., each year, specifically the 400,000 who, by choice or need, visit in the sweltering summer months, when the temperature on the mansion’s second floor has been known to hover around 100 degrees.

When conditions become that oppressive, Mount Vernon’s helpful guides, who are issued cold compresses for their wrists and necks, haul out the electric floor fans and stand vigilant for swooning guests. Pass out in George and Martha’s upstairs master bedroom and you’ll probably awaken outside in a rocking chair on the high-columned piazza that overlooks the Potomac River, with a glass of ice water in your hand and a breeze caressing your face.

Although other historic properties, such as Jefferson’s Monticello, have long been blessed with air-conditioned comfort, Mount Vernon waited, fearing damage to its priceless property.

“We’re very cautious here,” said Dennis J. Pogue, director of restoration at the site 16 miles south of Washington. “This building is our main artifact. It’s the most important thing we have.”

The 15-room, 11,000-square-foot mansion, which Washington called home for 45 years and where he died in 1799, is made of wood and has no insulation.

The private nonprofit association that operates Mount Vernon sought out the New York-based Carrier Corp. for the job after learning of the company’s work on the Sistine Chapel a few years ago.

The firm designed a computerized heating and cooling system that will keep the indoor temperature within about 10 degrees of the temperature outside. “Anything cooler, and the furniture could go into shock,” said Mount Vernon spokeswoman Sally McDonough.

The renovation, which is expected to cost about half a million dollars, will tear up the house as little as possible, curators say. The mansion’s old boiler-operated heating system, installed in 1899 on just the first floor, has been removed, and the open channels are being used for the new ductwork.

Mount Vernon was built by Washington’s father in 1735 and was renovated three times by Washington from 1754 to 1787, said historian John Riley.

During one of those alterations, Washington added the striking riverfront piazza, which extends the length of the house. Thought by some to be the mansion’s most distinctive architectural feature, it provided a spot for guests--then and now--to sit a spell and enjoy the cooling breezes off the river.

The mansion’s large central hall and aligned windows allow a cross-current to pass through the house, and the octagonal cupola on the third floor draws hot air up and out.

Weather conditions were of major interest to 18th-century farmers and plantation owners. “Very warm and sultry with appearances of rain--but none felt,” Washington noted in his diary entry for July 12, 1768, one of his many comments on the subject.

The Washingtons and their guests coped with the heat much as present-day visitors to Mount Vernon do: by indulging in ice cream and drinking plenty of cold beverages (Martha had a spiked cold punch that was particularly popular, according to Riley). The ladies carried fans with them, and the gentlemen traded their wool clothes for linen.

Carrier Corp. is donating its services, including engineering and design, materials and installation, a gift estimated at $300,000.