In about a week, 22 Washington buildings will be draped with banners urging observers to look at them not only as handsome, historic buildings but also as energy-efficient alternatives to new construction.

Washington is one of eight cities in which the National Trust for Historic Preservation will unfurl its campaign -- funded by a $34,000 grant from the Department of Energy -- arguing that there are energy savings in sparing buildings from the wrecker's ball.

"We suspect it's not going to be the winning argument to save a building, but on a political level, we think it can be used effectively," said Lynn Snoddon, vice president of the trust.

The banners will say how much energy -- translated into gallons of gasoline -- would be required to construct the buildings again. For instance, Beale House at 2012 Massachusetts Ave. NW, the red-brick headquarters of the National Federation of Bussiness & Professional Women's Clubs, will display a banner claiming that "to replace this building would require energy equal to 194,500 gallons of gas."

The Christian Heurich House at 1307 New Hampshire Ave. NW, headquarters of the Columbia Historical Society, will display a banner claiming it would cost the equivalent of 209,600 gallons of gasoline to replace it.

Others buildings that will display banners include the District Building, the Willard Hotel, the Hotel Washington and the American Security Bank.

The banners rely on a method of computing replacement costs developed by consultants to the Advisory Council on Historic Preservation. Rather than simply comparing the cost of heating and cooling a new building to the cost of heating and cooling an old building -- a comparison which frequently favors new buildings, the analysis includes both the energy costs of demolishing an old building and energy "embodied" in it.

"Once energy is embodied in a building, it cannot be recovered and used for another purpose -- eight bricks embody energy equivalent to a gallon of gasoline but cannot fuel a car," according to the advisory council.