Page 42 - Green Builder Homeowner's Handbook 2016

The Homeowner’s Handbook SEVENTH EDITION

A Breakdown on High-Performance WindowsINDOWSAREANIMPORTANTFACTORin

improving the performance of the building
envelope. But with so many options available,
selecting the right window can be challenging.

W To increase insulation, homeowners should
coatings, which can reduce energy loss by 30 percent to 50 percent,
according to the U.S. Department of Energy (DOE). Some windows
are tinted or coated with heat-absorbing glazing, which absorbs
solar radiation and reduces the solar heat gain coefficient, visible
transmittance and glare.

choose a double- or triple-pane window. Storm windows are another option for efficient windows. Though they

Between each pane is an insulating air pocket, so more panes means don’t add more insulation, but they can help reduce the amount of air

more insulation. These windows can be filled with gases such as argon flow through windows, which can help with heating and cooling costs.

or krypton to provide better insulation than air. The table below demonstrates the performance of common high-

In addition, insulated windows can include low-emissivity (low-E) performance windows compared to standard single-pane windows.

Glass Visible U-Factor Solar Heat
Thickness Gain
(Inches) Transmittance (Winter) Coefficient
0.25 0.81
Single Pane 0.25 (% Daylight) 0.70
0.125 0.67
Double Pane Insulated Glass 0.25 89 1.09 0.37
0.125 0.35
Triple Pane Insulated Glass 0.125 79 0.48 0.27

High Efficiency Low-E 74 0.36

Suspended Coated Film 70 0.29

Suspended Coated Film 55 0.25
w/ Argon Gas Fill
53 0.19

CREDIT: WHOLE BUILDING DESIGN GUIDE

Energy-Efficient Window Frames Glossary of Terms

Efficient windows don’t stop at just the pane. It’s also important Know the Lingo
to consider the type of window frame.
¦¦ Visible Transmittance: The
Composite Frames. These frames are made from composite wood products, such as percentage of light transmitted
particle board. They resist moisture and decay better than conventional wood, and typically through the window.
have the same or better structural and thermal properties.
Vinyl Frames. These frames have a hollow cavity that can be filled with insulation to ¦¦ U-Factor: The rate of heat loss.
increase their energy efficiency. To prevent sunlight from breaking down the material, they (The lower the number, the higher
usually are made from polyvinyl chloride with ultraviolet light stabilizers. the heat loss resistance.)
Wood Frames. Wood is a natural insulator, so these frames provider higher insulation
values. However, wood naturally expands and contracts in response to hot or cold weather ¦¦ Solar Heat Gain Coefficient
conditions, which may affect their performance. (SHGC): The amount of solar
energy transmitted, measured
CREDIT: U.S. DEPARTMENT OF ENERGY on a scale of 0 to 1. (The lower
the number, the less solar heat
40 GREEN BUILDER The Homeowner’s Handbook 2016 transmitted.)

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