It doesn't matter where you live in the country winter means less sunlight, especially in the northern states and particularly in Alaska. This lack sunlight not only affects the weather and temperature but also the solar radiation that pours through the windows and can add a large amount of heat to the building.

The Good Greenhouse Effect

With carbon emissions at an all-time high scientists are worried about global warming from what is now commonly known as the “Greenhouse Effect.” When the sun's rays hit a planet with no atmosphere, like the moon, the surface heats up. In the case of the moon this is a tremendous 107 degrees Celsius, or 224.6 Fahrenheit. And it goes down to -243 degrees Fahrenheit on the moon's night cycle.

The reason this does not happen to the earth is that the atmosphere prevents the intensity of the sun from baking the earth and, conversely, excess heat from reflecting back into space. This is what happens in a regular greenhouse and its effect enables plants to grow when its too cold outside. However, too much atmospheric density, like pollution, prevents the excess heat from escaping. This is the part that affects the polar ice caps and other melting that is abnormal.

Windows Create Heat

On a sunny winter's day even though the temperature may be below zero the radiation from the sun still streams in through southern-facing windows. You can feel the warmth in the air an on objects like a brick fireplace or a tile floor. This heat is retained in these objects after the sun goes down because they have a proper thermal mass for heat storage. Somehomes even have fans to move this heaqted air into other areas of the home.

Windows that are properly placed can increase this heat value and save the homeowner on energy bills. The key here is to avoid too much of a western exposure as this will cause problems in the summer when the arc of the sun swings in a more westerly direction. Unless it is shaded from outside the heat can affect the seals and shorten the lifespan of the window. As well, it will increase air conditioning bills. This goes for skylights and any other west-facing window.

A well-placed window, or windows, with a low-emissive, metallic coating will allow the sun in and slow the escape of heat through the glass. Even with a triple-pane window filled with heavy argon gas cannot stop the leakage of heat because it only has an R-value of around 4 whereas most new walls are R-19. However, the invisible metallic coating reflects heat back into the home where the thermal mass effect can hold it longer. Conversely, in the summer the window coating reflects excess heat.

How Thermal-Efficient Windows

Work Heat is transfered by three methods: convection, conduction and radiation. Old double-paned windows shed heat in these ways:

• Convection: Cold from the outside glass and heat from the interior of the home creates convection currents withing the glass allowing the heat to escape more freely.
• Radiation: Heat flows out through cracks in the window frame and through the glass.
• Conduction: Old windows rarely had thermal breaks, especially the aluminum ones. The heat left the home though metal sliders and casings.

The new windows are made of vinyl or wood with air pockets. Some even have foam cores. This prevents heat from traveling through the mass of the casing via conduction. In a triple-pane, low-emissivity, argon-filled window the convection process is slowed by the heaviness of the gas. This breaks the patterns of the tiny currents of air that move the heat through normal window glass.

Seasonal Affective Disorder

Another item in which can make a marked improvement is Seasonal Affective Disorder, or SAD. This is a psychological affliction had affects hundreds of thousands of people across the country and is linked to the lack of sunlight. Therefore this malady is most pronounced in the winter when the hours of daylight are diminished. In fact, the real problems with SAD have changed the way many architects design window systems for the home.

Functional Windows

The nostalgia for the old-style window systems, featuring such items as window boxes and atrium designs, has altered window designs. The extended bay windows also collect more sunlight than the normal, flat installations and allow for plants. This enhances the interior space and provides more oxygen, especially when most homes are sealed tight in the winter.

There is no doubt that the sun makes a big difference in winter living. Accepting the fact that the light will diminish during this season does not mean that darkness and large bills have to be the norm. Carefully choosing new windows, and their placement, will make this season more enjoyable.