Many of today’s thermopane windows are more than just simple insulated glass. There are ever changing methods that window manufacturers use in an effort to make insulated windows more energy efficient. The problem is that not all of them are designed to last as long as one would expect new insulated windows to last, and some are not as effective as manufacturers can make them out to be.
One common method that is available in modern insulated glass windows is filling the windows with Argon or Krypton gas. The problem with this method is that gases can leak out over time. But amount of time this takes is hotly debated, some saying it is almost impossible for the gas to leak out, while others state that the gas could be gone before the window is installed. Since the equipment required to test the level of argon in the window (or if there is any) is very cost prohibitive, few people can tell you if your gas has withstood the test of time.
But in the Charlotte area, gas filled windows are not the most effective way to improve energy efficiency, whether or not the gas can last. There is another alternative which is more appropriate for the warm Carolina climate, called a Low-E coating, which is more effective at reducing solar gain, but the coatings have their own faults.
There are two basic types of Low-E coatings: soft coat and hard coat. Soft coat can be used only on the inside of the thermopane unit and are much more easily damaged than hard coat. This means that a window repair process is impossible should the seal ever fail. Hard coat are more durable but slightly less effective than soft coat, and while they can be retrofitted to existing windows, often the cost of getting a retrofit Low-E hard coat is not worth the energy savings.
While these modifications can slightly improve energy efficiency, we don’t believe it would be wise to replace functional residential windows to gain marginal energy savings. Even Consumer Reports Blog declares that “It is generally not a good investment to replace windows just for energy-efficiency purposes.” We are of the opinion that as long as your window seal is intact, one of the most energy saving things Carolinians can do is to close their shades on those hot summer days.
