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Effect of Aluminum
Reflector Placement:
Infrared and visible wavelengths radiated by
the sun strike a building.
Such radiant energy is converted to some extent into heat by the first
surface it strikes.
Most building materials convert about 90% of the radiant energy into
heat and become hot.
In contrast, aluminum converts only 3% of the radiant energy into heat
and remains cool.
Placement of aluminum reflecting media determines which portions of the
building get hot. 1)
the roof surface itself is aluminum - roof and all surfaces below are
cool.
2) aluminum is hung below roof sheathing - roof surface and sheathing
are hot, areas below are cool.
3) aluminum is stapled to rafters - roof surface, sheathing, rafters are
hot, areas below are cool.
4) aluminum media is applied to surface of insulation - attic and above
is hot, areas below are cool.
5) aluminum is installed on ceiling - insulation, attic and all above is
hot, living space is cool.
Studies have been conducted wherein aluminum media was stapled under
rafters or layed on top of existing attic insulation. The top
surface of the insulation, receiving less radiation, is cooler than it
would have been without the reflector. This reduces the amount of heat
which moves through the insulation and into the living area.
Reductions in ceiling heat flow due to placing aluminum IR reflector
above R-19 attic floor insulation:
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