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Low-emissivity arena ceilings
have been around for about 20 years and yet there is still
some misunderstanding of their purpose and why they are beneficial
in ice arenas. Some people beleive that if they have a white
ceiling that is unsulated, a low-e ceiling will not help them.
Others beleive that a low-e ceiling will make the arena colder.
The fact is that a low-e ceiling
works because the material it is made of has a very low potential
to transfer radiant energy. Most objects and materials, including
bright white-faced insulation, have an emissivity factor of
.9; this means they are 90 percent efficient in transferring
their radiant energy to other objects. A good low-e ceiling
has an emissivity factor of .03, or is 3 percent efficient
in transferring its radiant energy. Like infrared heaters
radiant energy never heats the air, it only heats the objects
it strikes - in this case, your ice surface.
Radiant energy will always
flow from objects at a higher temperature to objects at a
lower temperature. The greater the temperature differential,
the faster the rate of heat transfer. Since your arena ceiling
is always warmer than your ice surface, there is a constant
transfer of radiant energy to the ice. When a low-e ceiling
is installed over the ice sheet, it interrupts the flow of
radiant energy to the ice. The low-e ceiling reduces the heat
load on the ice sheet by as much as 20 percent. Radiant energy
always flowa perpendicular to the surface that is emitting
it.
An incidental but very beneficial
side effect of the low-e ceiling is that it is highly reflective.
This substantially increases the perceived light level and
may allow you to decrease the number of light fixtures, resulting
in even greater energy savings.
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