One of the most common reasons to replace windows in a home is to improve energy efficiency. The right windows can stop air leakage and also prevent heat transfer through the glass, reducing both your heating and cooling bills. Here's a look at three features to look for in windows if your goal is to save energy:
The "e" in low-e stands for emissivity, which is a term that refers to the transfer of heat and UV rays through glass. Plan, standard glass (like the type old windows were made from) has a high emissivity. That is, it allows a great deal of heat and UV rays to pass right through it. This means that your heat has an easy time escaping your home in the winter -- and in the summer, the sun's rays warm your home, raising your air conditioning bill.
Low-e glass is coated in a special, metal-oxide material to reduce its emissivity. When UV rays hit the glass, most of them bounce off rather than travel through the glass. Similarly, heat from the interior of your home is reflected back off the windows instead of traveling through them and into the great outdoors. This can make a huge difference in your heating and cooling bills.
You cannot see the low-e coating on these windows; it is thinner than a human hair, but it is there going its job nonetheless. The emissivity of a window is indicated with a value called the U-factor. The lower the U-factor, the more energy-efficient the window (the less heat it will allow to be transferred).
Argon Gas Filling
For the greatest energy-efficiency, it's important to choose a double-paned or triple-paned window rather than a single-paned one. Less heat travels through your windows when there are multiple sheets of glass standing in its way! However, it's not just the glass itself that traps the heat in, but the gas between the panels of glass. This gas acts as an insulating barrier, slowing the transfer of heat. Standard double-paned or triple-paned windows are just filled with atmospheric air, but if you want to take your energy-efficiency to the next level, you should purchase ones that are filled with argon.
Argon transfers heat even less readily than air, reducing your heating and cooling bills even further. As an added bonus, the argon slows corrosion of the window material, so you don't have to worry about air leaks developing and letting your heat out. Argon works well in all climates, and since it only adds about $30–$40 to the cost of each window, it will pay for itself in energy savings rather quickly.
In addition to choosing the right glass and gas filling, you'll need to consider the style of window and how it is installed in your home. Though hung windows have become quite popular due to their looks, the best choice if you are aiming for energy efficiency is actually casement windows. This is the type of window that is mounted on hinges and opens when you turn a little crank.
Casement windows fit more tightly against the window sash than hung windows, so less air can leak through. The only more energy-efficient window option is a fixed window, which cannot be opened at all—and that's not a good choice for most homes. The primary limitation of casement windows is that they can only be made so big because they get too heavy for the hinges. If your windows are overly huge, you may have to go with hung windows.
If you're going to spend the money to replace your windows, make sure you're getting ones that are truly going to reduce your energy bill. With low-e glass, argon filling, and a casement style, it's tough to go wrong. Contact a company like Summit Valley Glass and Windows for more information.