An energy-saving tip: Hanging "strip doors" -- overlapping strips of thick plastic that hang over doors to allow for passage of goods or vehicles -- will block the flow of air from one place to another in your office, store, or warehouse. The strips can be used to partition loading platforms, conveyor belts, or refrigeration bins from heated or air-conditioned areas.

Strip doors vary in size, from 2 feet by 2 feet, for placement in front of a conveyor belt, to 16 feet high, for large warehouse or loading areas. The width of the strips varies from 4 inches to 36 inches, and the thickness can range from 0.08 inch to 0.16 inch. Prices range from $300 to $2,000, depending on the size of the doors.

Michael Kennon, product manager for the door division of King Co. of Owatonna, which manufactures strip doors in Owatonna, Minn., recommends that companies evaluate their air exchange and expected traffic flow before installing the strip doors. The effectiveness of the doors are limited by wind factors; strong gusts can penetrate the doors, he says. Thicker and wider strips are recommended for partitioning areas for trucks and industrial equipment; thin strips are recommended for areas wherc people or light goods will be passing through.

Jim Bedwell of Bedson Corp. in Memphis, distributors of the strip doors, says the plastic curtains can be used for purposes other than retaining heat. Flavorite Laboratories Inc., for example, uses the strips in its Horn Lake, Miss., spice-blending facility to separate work areas and keep spice particles from mixing. Other companies have used the doors for noise abatement, bird and dust control, and as insect barriers.