Hints & HELP!
the Window on High Energy Bills
submitted by Lorene Bartos, Extension Educator
article appeared in the September 15 Lincoln Journal Star
cooling your home in the summertime and heating it in the
winter costly for you? If so, windows may be part of the
problem. Almost half of United States homes have single-pane
windows. Homeowners with single-pane windows should consider
replacing them with new double-pane windows with high-performance
cooling-dominated climates, select gas-filled windows with
low-emissivity coatings on the glass to reduce heat loss.
For heating-dominated climates, select windows with spectrally
selective coatings to reduce heat gain. Parts of Nebraska
are in the northern, or heating-dominated, climate area.
The majority of the state is in the central, or both a heating
and cooling, climate.
homeowners decide not to replace windows, there are other
ways to improve the windows' performance. In cold weather,
close curtains and shades at night, and open them during
the day. In warm weather, install white window coverings
to reflect heat away from the house and close south- and
west-facing curtains during the day. Installing storm windows
also can reduce heat loss by as much as 50 percent.
uniform National Fenestration Rating Council label may be
found on windows made by participating manufacturers. The
label can be used to compare energy rating including the
U-value or thermal transmittance, solar heat gain coefficient
and visible light transmittance.
new windows means paying attention to correct installation
requirements for the particular window style. Incorrect
installation may lead to water moving into the inner wall
cavity and damaging wood and siding below the window as
the water moves downward. Be sure correct flashing procedures
are used and any weep hopes to allow moisture drainage are
not plugged. Some newer windows are meant to allow any moisture
that does get in to escape. If in doubt about the installation
methods, contact the manufacturer.
meet the EnergyStar compliant designation for windows, the
U-value for areas in the northern region must be 0.35 or
lower. In the central region, the requirements are a U-value
of 0.40 or lower and a solar heat gain coefficient of 0.55
or lower. EnergyStar windows must be NFRC rated.
characteristics of glass in windows:
Single glass- U-value: 1.1; R-value: 0.9; solar transmittance:
84 percent; visible transmittance: 90 percent
Single glass with storm window- U-value: 0.50; R-value:
1.5-2; solar transmittance: 70 percent; visible transmittance:
Insulated glass- U-value: 0.56-0.50; R-value: 1.6-2;
solar transmittance: 70 percent; visible transmittance:
Low-e insulated glass- U-value: 0.40-0.29; R-value:
2.5-3.5; solar transmittance: 58 percent; visible transmittance:
Low-e insulated glass with Argon- U-value: 0.34-0.23;
R-value: 2.9-4.4; solar transmittance: 58 percent; visible
transmittance: 76 percent
Insulated glass with suspended film- U-value: 0.23;
R-value: 4.1-8.1; solar transmittance: 41 percent, visible
transmittance: 71 percent
more energy saving tips on windows, visit www.eren.doe.gov/consumerinfo/energy_savers/windows.html.
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