HomeMy WebLinkAboutProduct Approval (4)Understanding Thermal Properties
On Glass Performance
J -Factor
ieasures how well your
kylight prevents heat from
scaping a living space.
• 0.15 > U factor > 1.20
• lower is better
Visible Transmittance (VT)
measures how much light comes
through the skylight.
• 0 > VT > 100%
• Personal Preference
Solar Heat Gain Coefficient (SHGC)
measures how much heat from the sun is blocked.
The lower the SHGC, the more the skylight is
blocking heat entering the living space.
• 0>SHGC >1
=4 • lower is better
Ultraviolet Light (UV)
considered the energy that accounts
for the majority of fading of materials
and furnishings.
Insulated Glass Thermal Properties Comparison
Glass
U -Factor
SHGC
VT
Single Pane, Clear
1.04
.86
90
Tinted/ClrTemp w/Argon
.48
.63
61
Low-e/ClrTemp w/Argon
.30
.72
76
Lo E2 240/ClrTemp w/Argon
.26
.25
39%
Lo E3 366/ClrTemp w/Argon
.24
.27
65%
11-o E3 340/ClrTemp w/Argon
.24
.18
39
•0>UV>1
• lower is better
UV
.73
.32
.50
.16
.05
.02
Condensation
Condensation in your home is caused by excess humidity or invisible water vapor in
the air. The warm air in your home can hold large amounts of this water vapor (much
more than cold air). When the moisture -laden warm air comes in contact with a cool
surface, the vapor condenses to form actual water droplets. This is the cause of the
condensation you see on the inside of your skylights or windows. The lower the
U -Factor & SHGC thermal numbers, the better result reducing condensation.
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