You've thought about replacing your windows, but is it worth the expense? How much of an improvement would new windows be? A lot! Two recent technological improvements have helped to improve the quality of windows.
Low-E Coatings Low- emittance (Low-E) coatings are virtually invisible metal or metallic oxide layers coating a window in order to suppress radiative heat flow.
Many Low-E coatings allow visible light through but reflect long-wave infrared radiation.
For a colder climate you might use a triple glazed Low-E window with three layers of glass and two Low-E coatings.
For climates with heavy heating and cooling loads, some Low-E glass is spectrally selective, reducing heat loss in winter and heat gain in summer.
Argon/Krypton Gas Fills The air between the layers in a window can conduct heat or cold.
Filling that space with more viscous, slow-moving gas minimizes that conduction, reducing the transfer of heat between the inside and outside.
Window manufacturers typically fill the space with argon or krypton gas.
Both gases are nontoxic, nonreactive, clear, and odorless and give a measurable improvement in thermal performance.
Tax Break for Energy-Efficient Windows In 2010 homeowners can claim a tax credit of up to $1,500 for upgrading their home with energy-efficient windows, doors, and skylights.
In other words, you can reduce your income tax by up to thirty percent of the purchase price (not including installation costs) for qualified products.
That's a nice incentive, but the real benefits arrive in the form of increased comfort and decreased energy bills.