I want to add some type of outdoor window covering to save energy and provide privacy and security. Are the exterior rolling shutters very energy efficient and can I still get light in through them? M.V.

A - If you are interested in saving energy and providing security against break-ins, exterior insulating rolling shutters are one of your best choices. They offer protection against high winds and storms and greatly reduce outdoor noise when they are completely closed. They are particularly effective for patio doors and large first-floor windows.Insulating rolling shutters can reduce the heat loss or heat gain through double-pane windows by about 50 percent. This results from both increased insulation and reduced air leakage around your window. In the summer, blocking the direct and indirect rays of the sun can lower cooling costs too.

Most residential exterior rolling shutters are made of interlocking horizontal hollow vinyl slats. They slide in aluminum channels on each side of the window and roll up into a housing. The housing is often located in the roof soffit out of sight above the window. Insulation-filled aluminum slats are also available for very large windows.

You can adjust the rolling shutter in several positions depending on your needs. For the maximum protection, efficiency, light and sound control, you completely lower and close the shutter.

If you want some light and ventilation, you raise the shutter slightly to expose the interlocking flanges. These flanges have many small holes in them. In this slightly raised position, the holes are exposed. There are enough holes to distinguish forms outside the window.

For more light and ventilation or when seeking passive solar heating in the winter, you roll up the shutter to any position. When it is completely opened, it is totally out of sight from indoors when looking out.

There are several indoor-operation methods for opening and closing rolling shutters. The simplest method is a hand crank to raise and lower them. Another method is a hand-operated, counter-balanced strap.

The most convenient method is an electric motor control. You use an "up/down" switch mounted on the interior wall near the window. Remote controls, similar to a garage door opener, are also available. There are even sensors that, in the event of high winds or excessive heat, automatically lower the shutter when you are gone.

You can write to me for UTILITY BILLS UPDATE No. 381 listing the manufacturers of insulating rolling shutters and detailed information on several efficient types. Write to James Dulley, The Deseret News, 6906 Royal Green Drive, Cincinnati, OH 45244. Please include $1.00 and a self-addressed STAMPED BUSINESS-SIZE envelope.

Q - My neighbor in my apartment building and I compared our electric bills, and mine is much higher than hers. We seem to use our appliances and lights the same amount. What could cause the difference? J. F.

A - Often your electrical usage patterns are actually quite different. If they really are about the same, you may have a faulty electric meter, although this is unusual. Call your utility company to have it checked.

There may also be a wiring problem, where some of her electrical outlets are mistakenly wired through your meter. You can easily test it by turning off all your electrical appliances, lights, clocks, etc. Then check the meter to see if it is spinning.