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WHAT IS L0/MIT-I/II?
HOW DOES L0/MIT-I/II WORK?
HOW WAS L0/MIT-I/II RATING VERIFIED?
WHAT IS A RADIANT BARRIER?
WHAT IS EMISSIVITY?
WHERE IS THE AIRSPACE WHEN USING L0/MIT-I/II?
DOES L0/MIT-I/II ADVERSELY EFFECT ROOF
SHINGLES?
DOES L0/MIT-I/II DEGRADE OVER TIME?
IS L0/MIT-I/II PERMEABLE TO WATER?
CAN L0/MIT-I/II BE USED ON SIDEWALLS?
CAN L0/MIT-I/II BE USED IN VENT-SKIN
CONSTRUCTION?
CAN L0/MIT-I/II BE USED WITH RADIANT HEATING SYSTEMS?
IS ATTIC VENTILATION IMPORTANT?
DO RADIANT BARRIERS LOWER HEATING COSTS?
DO RADIANT BARRIERS HAVE AN R VALUE?
DO YOU HAVE ADDITIONAL QUESTIONS?
WHAT IS
L0/MIT-I/II?
LO/MIT-I/II is a silver colored, non-thickness dependent, low emissivity
coating. When applied to non-porous building materials such as plywood,
OSB or plasterboard, LO/MIT-I/II lowers their surface emissivity to as
low as 0.21. It is classified by ASTM as an Interior Radiation Control
Coating (LRCC) and may be effectively used as an interior radiant
barrier.
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HOW DOES L0/MIT-I/II WORK?
LO/MIT-I/II works by changing the emissivity of the surface where it is
applied. Most building products such as wood, brick, and plasterboard
have high emissivities (0.7 0.95). When heated, they radiate most of
their heat to cooler surfaces. LO/MIT-I/II lowers their surface
emissivity to as low as 0.20, lessening their ability to radiate heat.
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HOW WAS L0/MIT-I/II RATING
VERIFIED?
LO/MIT-I/II Has been tested by the Lawrence Berkley National Lab per
ASTM E903-96. Laboratory application of LO/MIT-I on glass substrates
has lowered emissivity from .86 to .20 and increased diffuse
reflectivity from 7.3% to 85%. LO/MIT products can be applied to a wide
variety of substrates and normally will create a surface emissivity of
.20 - .26 and a diffuse reflectivity of 80 85%, depending on the
substrate used.
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WHAT IS A RADIANT BARRIER?
Heat flows in buildings occur in three ways: conduction, convection and
radiation. Radiant barriers address heat flows by radiation. Radiation
is the transfer of heat by electromagnetic waves known as thermal
radiation. Thermal radiation is a form of invisible light that travels
through the air from a warm to a cool surface. Warm surfaces, such as
roof decks warmed by the sun, will radiate or emit their heat to cooler
interior building surfaces. A radiant barrier is a low emissivity
surface placed in the path of thermal radiation that blocks heat
transfer.
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WHAT
IS EMISSIVITY?
Emissivity is the ability of a surface to radiate or emit energy in the
form of long wave electromagnetic radiation. It is represented by a
value from 0 to 1. The closer the value is to 1, the less effective the
surface is at impeding radiant heat transfer. Wood has an emissivity of
0.72. Thus, when wood is heated above the temperature of surrounding
surfaces, it will tend to transfer 72% of its heat energy by radiation.
LO/MIT-I/II, when applied to most non-porous surfaces, will decrease the
surface emissivity to as low as 0.20, allowing only 20% of the heat
energy to be transferred by radiation. The heat energy not transferred
by radiation would be transferred by conduction or convection.
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WHERE IS THE
AIRSPACE WHEN USING L0/MIT-I/II?
To function effectively, the low emissivity surface of a radiant barrier
must face an airspace of 2 or greater. A radiant barrier will not
function if sandwiched between two solid surfaces. LO/MIT-I/II, when
installed on the underside of roof decking, normally faces downward into
the attic, an airspace substantially larger than 2. If insulation is
installed in the cavity formed by the roof trusses and roof decking (as
in a cathedral ceiling), at least 2 should be allowed between the top
of the insulation and the LO/MIT-I/II surface.
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DOES
L0/MIT-I/II ADVERSELY EFFECT ROOF SHINGLES?
Absolutely not! LO/MIT-I/II has never caused shingle damage in any
installation. Extensive testing at the Florida Solar Energy Center has
shown that the use of radiant barrier results in, at most, a 2-3 degree
rise in shingle temperature. Contact our technical services department
for names of shingle manufacturers that guarantee their products when
used with LO/MIT-I/II.
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DOES L0/MIT-I/II DEGRADE
OVER TIME?
Unlike some insulation products, LO/MIT-I/II does not loose its
effectiveness over time. Test samples installed experimentally over 14
years ago still have the same emissivity levels today, as they did when
originally installed.
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IS L0/MIT-I/II PERMEABLE TO
WATER?
Yes! LO/MIT-I/II allows water vapor to permeate, and does not trap water
vapor within roof decks or sidewalls.
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CAN L0/MIT-I/II BE USED
ON SIDEWALLS?
Yes, but LO/MIT-I/II is normally more effective when used under roofs.
Low emissivity surfaces become more effective in controlling radiant
heat transfer as the temperature of the radiant heat source increases.
Roof surfaces are generally much hotter than sidewalls. However, in
tropical climates where no insulation is used in sidewalls, LO/MIT-I/II
can substantially help increase interior comfort levels.
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CAN
L0/MIT-I/II BE USED IN VENT-SKIN CONSTRUCTION?
Yes. In vent-skin roofs LO/MIT-I/II should be applied on the underside
of the outer roof skin facing down into the vent channel. On vent-skin
sidewalls LO/MIT-I/II should be applied on the inside of the outer skin
facing into the vent channel.
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CAN
L0/MIT-I/II BE USED WITH RADIANT HEATING SYSTEMS?
Yes. It is an effective heat reflector when used behind wood stoves or
on walls adjacent to ceiling mounted radiant heaters in commercial
applications.
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IS ATTIC VENTILATION IMPORTANT?
Very! Radiant barriers only control radiant heat loads. Good attic
ventilation helps control convection loads. Together they raise the
comfort levels and lower cooling costs. Venting to allow 2.5 air
changes per hour should be specified as a minimum
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DO RADIANT BARRIERS
LOWER HEATING COSTS?
Yes, but only modestly. They are most effective at lowering cooling
costs.
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DO RADIANT BARRIERS HAVE
AN R VALUE?
No. R-values apply only to solid insulation or to insulating systems
that control heat flows other than radiation. Thus, when LO/MIT-I/II is
installed with R-19 insulation, the combination yields a total R-value
of R-35 for heat influx. In this example. LO/MIT-I/II has an
apparent R-value of R-16.
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DO YOU HAVE ADDITIONAL
QUESTIONS?
Call the SOLEC Technical Services Department at 609-883-7700
or visit their web site at:
www.solec.org
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