Windows
Dont' Throw Your Money Out Them
By Jordan Mantz
Photo courtesy of Thermo Twin Windows
The complexity of your windows can dramatically increase the value of your home. There are a limitless number of different shapes and combinations of shapes you can use to add a striking effect to your home. Of course, windows do the obvious; they provide light, allow fresh air in and give incredible views both inside and out. However, windows also represent the number one source of heat loss in the winter and heat gain in the summer.
The larger the square footage of window coverage in your home, the better the chance you have of an inefficient home. That is why great care should be taken when deciding on the style and type of windows. The proper combination of window elements and technologies should be strongly assessed.
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| Photos courtesy of Anderson Windows |
If you’re feeling constant drafts from your old windows, it may be time to replace them. Today’s technology allows windows to be much more efficient than those made as little as ten years ago. Newer windows can reduce your heating and cooling costs by as much as 50 percent. Newer homes can experience drafts due to original windows not living up to initial expectations. Not making the correct choice during initial construction can also affect your home’s energy efficiency in the long run.
Due to the increased cost of heating and cooling, windows and their efficiency are being focused on more than ever. In the past, the most important factor in deciding what windows to choose was the desired look. Now the homeowner must factor both efficiency and beauty equally. There’s no doubt new windows will help improve the look of your home both inside and out, but energy efficiency should be final deciding factor of a new purchase.
Windows are one of the most expensive investments you can make in your new or existing home. Coupled with the rising energy prices and the uncertainty of future heating and cooling trends, now more than ever, the homeowner must take a very close look at energy efficiency as it relates to windows.
When it comes time to purchase new windows, you should know the basics and be familiar with the basic terminology and rating systems.
TECHNOLOGY
Keeping heat in (or out) U-Factor
To put things simply, the lower the U-factor, the greater a window’s resistance to heat flow will have, and, in turn, the better its insulating value will have. Windows lose and gain heat by conduction, convection, radiation and air leakage. This heat transfer is expressed with U-values, or U-factors. A lower U-value indicates higher insulating value.
The technical specifications for windows list values for air leakage as cubic feet per minute per square foot of window. Look for windows with certified air-leakage rates of less than 0.30 cfm/ft2. Lowest values are best.
Conduction is the movement of heat through a solid material. The less conductive the material, the easier it is to impede the heat flow.
Convection is also a means of losing heat through windows. In the winter, warm indoor air hits the interior window surface of the glass. The air cools, become dense and moves towards the floor. As the cold air drops, warm air rushes in to replace the colder air. This starts a convection loop or a cold draft.
Radiant Transfer is the movement of heat as long-wave heat energy from a warmer body to a cooler body. Clear glass absorbs heat and radiates it outdoors. Coatings on glass can help in reflection.
There are many factors to consider when making the final decision on your windows. The climate, total window area, landscaping, heating and cooling system, level of insulation and house design all play an important part in making a proper selection. Keep in mind, just because a window has certain energy performance properties, it does not mean it will be the most cost-effective window to install. The best thing to do is to ask the right questions to a window’s professional. If they can’t tell you a specific reason why they are suggesting a particular window, go elsewhere for advice.
If you do your homework and choose the correct professionals, windows can be a net energy gain. The payback period for selecting energy-efficient units ranges from two years to ten years. If you need longer than ten years for your payback, ask your consultant why. More durable and efficient windows may cost less over the life of the window because of lowered maintenance, energy bills and replacement costs. Choose wisely and do not be pressured by window companies that are simply trying to sell you the highest priced windows they supply.
If you make an educated decision, your home will be more energy efficient and you will be more comfortable because of it.
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