Qualifying
for the $200-$500 federal tax credit on new windows and doors depends on two
measurements, U-factor and Solar Heat Gain Coefficient.
Just because windows or doors are Energy
Star-labeled doesn't mean they're eligible for a federal tax credit. And with
costs running about $500-$1,000 per window including labor, it's wise to know
something about the scientific lingo and numbers on the product labels you're
likely to encounter. Here's your pro-level label-decoding guide so you can be
sure you're buying qualified products.
Which Labels Matter?
The
two labels you should look for: The U.S. Department of Energy's blue-and-yellow
Energy Star label, which specifies the climate zones the product is certified
for, and the white National Fenestration Rating Council label. Nonprofit NFRC
is the industry-recognized certifying body for windows and doors. It reports
raw numbers only; Energy Star tells you whether those numbers constitute
superior performance, putting its seal of approval on those products that meet
its standards.
To confuse matters, DOE has issued a blue
label that manufacturers can use to signify that a product qualifies for the
tax credit. But DOE doesn't require that manufacturers include it.
What You Need to Get the Tax Credit
For windows or doors to qualify for the
credit, two NFRC-supplied measurements must each be equal to or less than 0.3,
regardless of climate: U-factor and solar heat gain coefficient (SHGC). You
must also have the manufacturer's signed statement that the product complies
with IRS requirements. This either comes with purchase or can be downloaded
from the manufacturer's website.
Don't be swayed by ratings the manufacturer
may post on its own label. A window or door's frame and other components
(weather stripping, sidelights, transoms) can significantly affect its energy
efficiency, so NFRC measures based on the entire unit, not just the window glass
or door slab alone. Manufacturers, on the other hand, sometimes report values
that don't take the entire unit into account, according to Energy Star.
A
Guide to Measurements
The NFRC label typically lists five
measurements, including the tax credit-critical U-factor and SHGC. The other
three are somewhat less important to energy performance, according to Energy
Star, but can help you judge how well a window or door will perform in a
particular application-for example, whether it'll let in enough light.
Where
you live affects which measurements are most important, but the tax credit
requirements are uniform across the country. There are four Energy Star climate
zones, differentiated by whether heating, cooling, or a mix of the two is most
critical to energy performance.
1. U-Factor
Range: 0.20 to 1.20
The lower the number, the better an insulator
the window or door is.
Tax credit qualification requirement: 0.3 or
less
Efficient Windows Collaborative climate
recommendations:
•Northern:
0.35 or less
•North
Central or South Central: 0.4 or less
•Southern:
0.60 or less
A low U-factor means that less heat escapes
in the winter, which makes it particularly important in cold northern climates,
according to the Collaborative, a coalition of government agencies, research
organizations, and manufacturers that promote efficient window technology.
2. Solar Heat Gain Coefficient (SHGC)
Range: 0 to 1
The lower the number, the less solar
radiation-and heat-the window or door allows inside.
Tax credit qualification requirement: 0.3 or
less
EWC
climate recommendations:
•Northern:
The highest you can find (paired with a low U-factor) if cooling isn't a
significant concern; up to 0.55 if cooling is a significant concern.
•North
Central: 0.4 or less for climates with significant air conditioning; up to 0.55
for climates with moderate air conditioning.
•South
Central or Southern: 0.4 or less.
SHGC refers to the solar radiation a window
or door allows inside. Seek the lowest possible SHGC rating in warm climates to
minimize the use of air conditioning. Look for a slightly higher number in
cooler climates so that the sun can help heat your home in winter, but be sure
to balance SHGC with an efficient U-factor for your area.
3. Visible Transmittance
Range:
0 to 1
Lower number means the room will be dimmer; a
higher number means the room will be brighter.
Tax credit qualification requirement: none
This
number applies to windows or doors with windows only. Visible transmittance is
the amount of light a window allows to pass through. With older window glazing
techniques, VT and solar heat gain were basically the same; the brighter a
room, the hotter it got. But new technologies allow windows to let in lots of
light while the room stays cool.
Consult VT numbers if you're looking to reduce
glare in a room or fill it with natural light, but be warned that a very low VT
may mean you have to use artificial lighting even during the day.
4. Air Leakage
Range: N/A, but .0.3 is standard building
code
The lower the number, the more airtight the
window or door.
Tax credit qualification requirement: none
This number, expressed in cubic feet per
minute per square foot of window/door area, represents the amount of air that
the window or door's frame allows to pass through. Energy Star standards don't
consider air leakage because it's difficult to measure accurately and can
change over time as frame materials expand, contract, or warp in place,
according to the EWC. Still, this measurement can help you compare similar
products, especially if they'll be buffeted by the elements.
5. Condensation Resistance
Range: 1 to 100
The lower the number, the more condensation
the window or door allows to build up.
Tax credit qualification requirement: none
Condensation resistance is a measure of how
much moisture a window or door allows to build up on the surface (which can
drip onto wood and cause mold or discoloration) or between glazing layers
(which can't be clean and blocks your view). Energy Star-rated windows tend to
resist condensation well, so this number won't likely affect your purchase
decision.
Article
From HouseLogic.com | By: Karin Beuerlein | Published: 01/04/13
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