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What is Low E glass?
Low
E glass is a wonderful new technology. Window glass underwent revolutionary
changes in the 1970's. Insulated glass (two or more pieces of glass
with a dead air space between) made its debut in the early 70s.
Low E glass (Low emissivity glass) was introduced in 1979. Second
generation Low E glass (dubbed Low E squared or Low E2) was introduced
in 1983 with several companies claiming to have invented it. Since
then the major glass companies have made improvements yearly. Low
E glass works by reflecting heat back to its source. It does this
by utilizing an ultra thin metallic coating on or in the glass.
What are Low-E Coatings?
Low-emittance (Low-E) coatings are microscopically thin, virtually
invisible, metal or metallic oxide layers deposited on a glazing surface
primarily to reduce the U-factor by suppressing radiative heat flow.
The principal mechanism of heat transfer in multilayer glazing is
thermal radiation from a warm pane of glass to a cooler pane. Coating
a glass surface with a low-emittance material and placing that coating
between the glass layers blocks a major amount of this radiant heat
transfer, thus lowering the total heat flow through the window. The
benefits are a cooler home in the summer and a warmer home in the
winter. Low-E coatings are transparent to visible light. Modern Low
E coatings are very clear indeed, unlike the early brown tints we
used to see. The infrared light(heat) from sun is powerful. When sunlight
strikes an object it absorbs the infra red spectrum and heats up.
Objects include sidewalks,rocks, anything outdoors that can absorb
and radiate heat. As these objects cool off, they emit a low powered
form of IR light. Low-E glass reflects this form of energy. Modern
Low E glass senses summer by the angle of the sun in the sky and acts
much like a heat mirror, keeping heat and damaging sun rays out. In
the summer this helps to keep your house cooler, as the heat from
objects outside is kept outside. In the winter, Low E reverses the
process and heat is reflected back into your house by the low-E glass.
Different types of Low-E coatings have been designed to allow for
high solar gain, moderate solar gain, or low solar gain and local
window companies order glass custom made for our climate. Cardinal
glass Low
E2 172 is an example of a high end Low E(squared) glass customized
for the Northwest. Someone in a very hot climate would choose a Low
E coating designed to prevent summer heat with little concern for
winter heat savings. |
How Low E glass works for you in cold weather:
All
objects emit energy as some form of radiation. Heat from a furnace,
or even a person, is "long wave" radiation. Light from
the sun generates "short wave" radiation. Thermaflect
knows the difference.
In cold weather, you spend your energy dollars generating long wave
radiation. That heat moves toward your cooler windows, but Thermaflect
acts like a mirror, reflecting it back inside to save you money.
Thermaflect maximizes the beneficial energy of the sun. The coating
selectively transmits the visible light (short wave energy) from
the sun into the room, while reflecting away the ultraviolet radiation
that can damage curtains and upholstery.
The short wave energy is then absorbed by objects such as sofas,
carpets, even people, and is radiated from them as long wave heat.
Thermaflect acts like a shield to this heat, preventing most of
it from passing back out the windows!
What's more, Thermaflect glazing with low conductance spacing is
10% warmer, saves 5% more heat, and reduces condensation up to 80%;
so the room is more comfortable all around.
The total result for you is a better living environment and lower
heating costs. With modern Low E squared glass the results are even
more impressive! Cardinal glass and PPG's newest generation of Low
E squared glass provide up to a 100% improvement over the first
generation of Low E which was still very impressive. Glass just
keeps getting better every day. Cardinal’s
LoE²-172 blocks 84 percent of the sun’s harmful ultraviolet
rays and delivers a remarkable 96 percent performance improvement
in winter night time insulation (R-value) compared to non-coated
air-filled insulating glass. However, it is virtually invisible
to the eye
How Low E glass works for you in hot weather:
Where
vinyl replacement windows are exposed to direct radiation, Low E’s
(Heat Mirror unique multi-layered coating blocks unwanted ultraviolet
radiation and reflects away infrared radiation that can add heat to
the inside of your home and damaging rays that cause fade.In the summer,
the sun is at a higher angle in the sky and less likely to stream
directly into your window. Also, roof overhangs, trees, and tall shrubs
serve to deflect sunlight from some windows, shield the more frequent
use of blinds, drapes, and other window treatments also helps block
unwanted heat. But you still benefit from Low E glass.Sunlight becomes
long wave heat radiation when it is absorbed by things outside such
as your driveway, shrubbery, or patio. Low E glass acts a a shield
to prevent this heat from entering your home through the windows,
so your air conditioner does not have to work overtime.With Low E
, you stay comfortable and your cooling costs stay lower - without
sacrificing sunlight. Cardinal’s
LowE²-172 blocks 84 percent of the sun’s harmful ultraviolet
rays thus protecting your draperies, carpets, and furnishings from
fading. |
Low E glass keeps working for you all year
long.
In the winter valuable heat is reflected
back into your home to keep you warm and reduce heat loss, giving
you comfort while saving you money.
In the summer, unwanted heat is reflected
back from the windows keeping heat out making your home more comfortable
during the hot days, while greatly reducing fade to your draperies
and carpets.
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