A Guide To Buying Energy Efficient Windows.
The following is a guest post by Nan Fischer, a Certified EcoBroker specializing in green real estate in Taos, NM. Check out her website www.nanfischer.com, and follow her on Twitter for a daily green news feed, www.twitter.com/nan_fischer.
Windows are one of my favorite topics. I love windows. I have lots of them. I like to feel like I am outside. If I had 100 acres, I’d build a glass house right in the middle. Windows today are much more efficient than they were ten years ago. If you have the inclination and the means to replace your old ones, do! When I remodeled two years ago, I replaced about 2/3 of my windows, and it made a huge difference in my heating bill.
Today’s windows are made for the different orientations in your home. Some keep heat out, some let it in. Also take into consideration views you want to take in or block, natural lighting and furniture placement.
When you are shopping for windows, this information will tell you about window performance:
- U-factor rating of the National Fenestration Rating Council (NFRC) – the lower the number, the more efficient the window, based on the glass, frame and spacer material.
- Solar Heat Gain Coefficient (SHGC) – This figure lets you know how much heat a window transmits. For passive solar gain, this number should be higher than .6. For windows on the north side that let sun in during the summer, this number should be lower to block the heat.
- Visible Transmittance (VT) – This number, between 0-1, states how much light comes through a window. For passive solar, this number should be high.
- Low-e – low-emissivity. A thin, invisible coating on the glass controls the amount of heat moving through it in both directions, in and out. This affects the U-factor and the SHGC. Low-e windows can save you 30-50% on your energy bills.
For passive solar applications, you want:
- A high SHGC
- A low U-factor
- A high VT
- Low-e windows
For northern orientation, you want:
- A low SHGC
- A high U-factor
- A low VT
- Low-e windows
Talk to a reputable window distributor, read the labels on the windows, and check out these websites for more information – www.energysavers.gov and the website of the NFRC, www.nfrc.org.
You may also like:
- More Affordable Energy-Efficient, Lower Emission Cars.
- Solar Energy Is Not New.
- Financial Incentives For Energy Efficiency In New Mexico.
- Energy Efficient Micro Appliances.
- Guide To Finding Safe, Eco-Friendly Sunscreen.
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“For northern orientation, you want:…A high U-factor”.
Are you sure? Other things being equal you almost always want a low U-factor.
Generally speaking a well designed building will have a smaller area of windows on the north (or, to be inclusive of the southern hemisphere, the poleward) face so U-factor may well be less critical than other considerations but still a higher U-factor is not desirable in itself.
Don’t forget about the new energy credit from the government. You can get up to $1,500 in tax credit back!
I want to buy a good quality window. All the companies tell me that what they sell is the best. So how can I make a decision considering quality price warranty and labor?