I want to get replacement wood windows to save energy, reduce drafts and sweating, and block outdoor noise. Are wood windows as efficient as other types and what selection factors should I consider? K.D.

A - Wood-frame and sash windows are very energy-efficient and attractive. Being made of wood, the frame and sash can have very-detailed contours for the best appearance and fit with the styling of your house.Wood itself is an excellent insulator and good-quality windows maintain their airtightness for many years. When you couple this with the new super-high-efficiency glass at R-8 and R-9 insulation levels, replacement windows can cut the heat flow through your windows by 80 percent or more. It also reduces the fading of your furniture and curtains.

When you select windows, the operating type is very important, both for aesthetics and efficiency. Swinging-types of windows (casement, awning and tilt/turns) are most airtight. The weath-erstripping seals in compression when the window is closed.

The more-common sliding windows (double-hung, single-hung and horizontal slider) are more difficult to seal well. The sliding joints between the sash and frame allow for more air leakage and tend to wear more than the compression-type seals on swinging windows.

You have several options for the type of exterior finish on wood windows. Aluminum- or vinyl-cladding covers and protects the exterior wood surface. These are available in just a few colors - usually white, brown and sometimes gray and tan.

The better quality non-clad, bare wood windows use a new super-high-performance paint (guaranteed for 10 years). The exteriors are relatively maintenance-free. For custom and high-quality work, you can get windows made of cypress, mahogany or teak at a premium price.

The interior of most wood windows (even exterior-clad windows) is bare or primed wood so you can paint them to match your rooms' decor. The wood is usually pressure treated with a non-Penta preservative to retard warping.

The new two-way-opening tilt/turn window is relatively new to the United States but is popular in Europe. You can tilt the top inward several inches for ventilation, yet still be secure. For more open area, you can close the top and swing the window inward completely from one side. When locked closed, it is fixed into the frame at four to eight points for security.

You can write to me for UTILITY BILLS UPDATE No. 292 listing 24 manufacturers of high-efficiency wood windows, type of material and cladding used, operating types available, options, and information on the new super-high-efficiency types of glass. Write to James Dul-ley, The Deseret News, 6906 Royal Green Drive, Cincinnati, OH 45244. Please include $1 and a self-addressed STAMPED BUSINESS-SIZE envelope.

Q - I have closed off the supply air register to an unused bedroom to save energy. Is it also important to close the return air register from it? There are no movable louvers in it to close. C.F.

A - It is important to block off both the supply and return registers. You can close the baffle in the supply duct leading to the room. For a better seal, stretch plastic film beneath the register.

The return air register often doesn't have louvers. For the neatest appearance, remove it and stretch some plastic film behind it. Screw it back in place. Then, using a sharp knife, carefully cut off the excess around the edge of the return register cover.

James Dulley has written a 100-page book, SOLARIZE YOUR HOME, compiling 22 solar energy-related Utility Bills Updates and the related columns. Solar energy topics include space heating, water heating, air-conditioning, greenhouses, skylights, swimming pools, cooking, and passive houses. Included are names and addresses of manufacturers of high-efficiency solar energy products, many low-cost do-it-yourself solar projects, and floor plan layouts of energy-efficient passive solar houses.

You can order this book directly from James Dulley for $9.95 (includes postage and handling) with check or money order (payee - James Dulley). Mail to James Dul-ley, SOLARIZE, 6906 Royalgreen Drive, Cincinnati, OH 45244.