Old buildings adapted to new use outnumber newly designed buildings eight to seven among the 15 winners of national honor awards for design excellence chosen by the American Institute of Architects this year.

This is in keeping with the still growing trend to "recycle" ornate, old structures that have outlived their original purpose rather than tear them down. The trend is due to a change in public taste and the fact that new construction has become just as expensive as renovation.

The seven-member AIA jury, headed by George M. Notter Jr. of Boston, said it was not concerned with authentic restoration so much as "excitment derived from something really special" in the design of the recycled building.

The greatest popular and commercial success among the recycled award winners, no doubt, is the Faneuil Hall Marketplace in Boston. Architects Benrating Thompson & Associates turned teh deteriorating historic wholesale market into a lively "people place" which is atttracting a million people downtown every day.

Amont the other awarded recycling jobs are: an old school converted into the Center Stage theater in Baltimore (James R. Grieves, architect); the old Carnegie mansion converted into the Cooper-Hewitt Museum of Design in New York City (Hardy Hoizman Pfeiffer, architects); a burned-out factory converted into a lucury apartment house in New York City (Bernard Rothzeid, architect); and an old police station converted into a museum of modern art in Boston (Graham Gund, architect).

A Washington, D.C. winner is Hugh Newell Jacobsen for transforming a Gothic Revival cottage in Chevy Chase into a modern house suitable for a modern art collection. Jacobsen has won 12 national AIA awards.

Among the new buildings honored are Skidmore, Owings & Merrill's addition to the Art Institute in Chicago and the late Louis I. Kahn's Yale Center for British Art - quite possibly the late master's best work.