“ Windows,”as the advertisers for glass companies often expound, “bring the outside . . . indoors.”

Yes there is nothing more impressive than a two-story wall of architecturally-designed windows that allow a unfettered view of a natural wonder like an ocean view or harbor lights at night. It is also true that glass, even double and triple-paned, has one of the lowest R-values of any material on the home. This means that windows have very little insulating qualities and are portals for energy wastage. Depending on how good the manufacture, and the number of panes, windows may “bring the outside . . . indoors” in terms of energy bills.

Heat moves from warmer to colder areas. Heat will penetrate a window on a warmer day but will escape through a window on a cold night.

Conveyor of Cold or Greenhouse?

Recent government studies have shown that windows contribute as much as 10% to 25% of your heating bill. In the winter cold is transferred through the glass, imperfections in the insulating around the sash and by transfer through the glass frames. Old windows, especially those with aluminum frames, need a thermal break. This is a space between the outside and inside sash so that the temperatures are not transferred this way.

The result is that windows help keep your furnace going in the winter and, during the summer months, your air conditioner working harder to cool hot air generated by a true “greenhouse effect.”

Replacing Windows?

If your windows have old, leaky wooden-framed windows or any old windows where the wood around the sash is rotting you be better off putting in new ones. It is goo to install Energy-Star-rated windows, which help a great deal. If you live in the southern areas look into new solar control spectrally selective windows, which can cut the cooling load by 10% to 15%.

What Are U and R-Values?

In order to put a measurement on heat transfer there two standardized norms U-values and R-values. U-values are how much heat is allowed to pass through materials. R-values are the opposite. They are a gauge for how much heat loss the material resists from passing through it. Therefore:

• A high R-value indicates energy efficiency - R-25 is better than R-15, for example

• A low U-value indicates energy efficiency - U-0.20 would be better than U-0.30.

Window Treatments and R-Value

Believe it or not you can cut down on losing energy just by have drapes or window coverings of a decent thickness. In many old movies you see large, heavy velour draperies which were, among giving a air of majesty, kept the heat from the open fireplaces from going out through the large, single-panes windows. And even though our windows have drastically improved window treatments can add substantially to your savings.

Types of Window Treatments

1. Common Drapes: Depending on the thickness, and how well your window is sealed from air leaks common, domestic drapes and curtains will cut down on energy loss. This works in tandem with keeping the drapes closed when heat transfer is the greatest: south-facing windows in the summer and north-facing in the winter. In colder climates the drapes can be open to take in the short sunny hours to let heat inside.
   
   

2. Thermal Drapes: These can be bought at the store or made. Generally they are a normal drapery with a thermal layer inside to keep the heat in, something like Thinsulate®. For a cheaper solution you can use a layer of bubble-pack.

3. Aluminized Mylar®: By adding a thin layer of aluminum into Mylar® you get a very light foil-like material that reflects up to 99% of light, including much of the infrared spectrum. This material, used in the space industry for reflecting sunlight, is also used in emergency situations for keeping victims warm and in any area which requires a thermal dam. Like thermal drapes it can be sandwiched between drapery material and is used with both bubble-pack and fiberglass insulation for house wrap insulation. It's benefits include a warmer home in the winter and a cooler one in the summer.

    

    

4. Shutters: With versatility in mind shutters could be your answer. Many types fit right inside the window frame and, unlike, drapes can cut the energy loss at the window pane. As well they do not have to be taken off during the day because most of them open like Venetian blinds. In this way you can regulate the direct sunlight on very hot days.

5. Venetian Blinds: These work to cut out the sun's rays but are not on the top R-value list for winter use as they do not seal

    

    

    

    

    

    

6. Thermal Plastic: With an estimated R-Value of 4 to 5 per square inch a sheet of plastic over the window is a cheap option for winter. Many inexpensive kits are available where plastic sheets are attached to the window frame with 2-way tape. Then the plastic is tightened into a transparent pane with a hair dryer. The result is a tight, leak-proof shield. However, it would have to be taken off in the spring otherwise your home could turn into a greenhouse.

7. Removable Sealer: (This works best for cold climates)With old windows, especially sliding ones, you can cut down or eliminate drafts by applying a removable sealer along all seams. The sealer goes on like silicone sealer but is easily removed in the spring.

Covering windows for greater energy conservation is definitely an easy thing to do. How much you want covered, and what materials you want to use, affects this savings.