Window shades can help save heat

One of the best places to start saving energy in a home, winter and summer, is at the windows. Various studies show that from 30 to 50 percent, and sometimes more, of the total energy in a typical house can literally fly out the windows if they are not properly airtight and the glass is not properly insulated by shades, shutters, and draperies.

Glass windows, according to the US department of Energy, are second only to uninsulated roofs and attics as energy wasters. Before considering any kind of window treatment, this department urges people to stop all air leakage around windows. It warns that insulating the glass, without correcting the leakage, will make little difference in fuel consumption and savings.

According to one study, an inexpensive standard light, opaque, vinyl-covered window shade, costing $10 or less, could be one of the most effective means of blocking heat transfer through glass, and therefore energy waste through windows , the year round.

The homeowner using shades for insulation will benefit most by following these steps:

* Make sure that your shades are well fitted to your windows. This means shades should have a minimum of space between the vertical edges and the window frames. They should hang close to the glass to minimize air movement and form a barrier of insulating air between the shade and the window.

* Mount the window shade inside the window frame for maximum energy savings. Such placement, the study says, is twice as effective as mounting shades on the wall outside the window frame.

* In summer, pull shades down to the sill during hot, sunny hours, since the study shows that drawn shades block out almost two-thirds of the heat generated by the sun's blistering rays. In winter, shades should be raised during the daytime, especially on the sunny side of the house, to let in the maximum of sun heat. After dark, in winter, the shades should be lowered to the sill to retain almost one-third of the buildup of indoor heat. Shades are thus used to help keep out undesirable solar radiation in summer and to let in and retain valuable solar radiation in winter.

Because the sales of thin-slatted Venetian blinds have more than doubled in the past few years, companies have recently introduced types of which are finished with a light-absorbing dark on one side, the room side, and a light-reflecting bright on the other. Cost is about one-third more than for standard minislat blinds. During the winter they should be kept open during the day and closed at night to form an insulated air pocket to keep in heat and keep out cold.

Woven woods, too, are good insulators, and keep a lot of heat and cold outside the house. Such blinds are also, decoratively speaking, one of the most handsome and long lasting window coverings.

Gordon Clements, vice-president of Hunter Douglas Window Products, says that many times a combination of insulationg techniques will achieve the best results. He suggests 'the layered look' combining a shade, Venetian or woven wood blind, with a thermally line drapery which can be drawn together for more warmth at night.