Energy efficiency is always a sought-after feature when selling a home, and the more information a real estate agent can supply buyers, the better. A double-pane window consists of two pieces of glass with air between them — essentially, air or another gas acting as insulation sandwiched between glass.
In 1947, Pittsburgh Glass introduced double-pane glass windows for the first time. Prior to this time, individual storm windows were installed in homes each autumn and removed each spring.
The air between the existing window and the moveable storm window acted as insulation. There was no protection against heat entering a home in the summer, but central air conditioning was not universally available for residential use, so preventing the escape of cooled air from the interior of a home was not yet a consideration.
The energy crisis of the 1970s saw renewed interest, research and development in double-pane windows.
Advantages of double-pane windows include noise reduction, lower utility bills, and maintaining room temperatures when weather conditions outside are changing. Double-pane windows will prevent condensation, or moisture, on the inside of the window and are eco-friendly.
Most importantly for homeowners, they add value to a residence, and over time, they will more than return the initial expense in savings on heating and cooling. Of course, be aware that every window in a home must be double-pane in order to reap the rewards.
How it works
Argon gas is the most commonly used type of gas in double-pane windows. Both nontoxic and dense, argon gas not only slows but decreases the transfer of energy. Krypton gas, which is denser than Argon gas, is even more energy-efficient.
Other gases that have been used in double-pane windows include xenon gas, nitrogen, and oxygen. Coatings on the exterior pane which are Low E or low emissivity, will reflect heat from the outside and reflect solar energy. Tinted glass also cuts down on the sun’s glare and prevents heat from entering the window.
Double-pane windows are not without downsides, such as leaks or compromised vapor locks and seals. Argon gas can leak at a rate of 1 percent per year, decreasing the window’s efficiency.
Window specialists can repair window frames and insert new gas to increase the lifespan of the window.
The effectiveness of double-pane windows is measured in the heat value or “U” value of the window. The lower the “U” value, the better insulated the window and the greater the efficiency.
The heat resistance value, or “R” value, is another unit of measurement used with double-pane windows. Single pane windows have an “R” value of 0.85, while double-pane ones have a value of 2.7 to 3.6. Clearly, double-pane windows are far more efficient than single-pane.
Having the ability and the vocabulary to discuss different types of windows and knowing about their energy-efficient capabilities is beneficial for real estate agents who are selling both new construction and renovated properties. Older homes, without the benefit of double-pane windows, can be upgraded to prevent heat loss and keep cooled air inside.
Realtors who can answer simple questions about windows will clearly have a strong advantage as global warming becomes more predominant.