Convection
One
of the most effective ways to increase thermal efficiency is to
minimize convection by keeping cold air "out of circulation".
The focus is on convection as it relates to attic insulation, particularly
blown-in attic insulation.
The
principles of convection are important to understand both to minimize
its undesirable effects, and also to better explain preventative
measures. Convection is the transfer of heat via the movement of
air. Hot air is less dense than cold air, so it tends to rise; the
denser cold air tends to sink. In winter, currents of hot air rising
and cold air sinking, are created within the home by the heating
system (hot air rising), and by heat loss through conduction and
air infiltration (cold air sinking).
The
better a home is insulated and the more effectively air infiltration
is controlled, the less convection there is inside the house. The
interior air is allowed to approach a state of equilibrium, and
the temperature within the home remains more uniform.
Convection
In Attics
Convection
is a natural process that can be controlled through the proper application
of insulation. In a cold un-insulated attic, heat conducted through
the ceiling warms the air near the attic floor. The warm air rises
toward the roof, where it loses its heat. This cooled air then sinks,
and is replaced once again by warmed air from the attic floor. This
continuous process is called a convective loop, and it is very effective
at transferring heat. Fortunately, insulation breaks the convective
loop by greatly reducing the conduction of heat from the ceiling
to the attic air.
Blowing
Wool Insulation
In
large measure, the performance of blown insulation products is controlled
by the installer. There are two important guidelines that must be
consistently followed to ensure that the insulation is properly
applied over the entire attic area:
- The
insulation must be applied at or above the correct density for
the desired R-value. This is often checked by counting the number
of bags specified for the area to be covered.
- The
insulation must be applied at or above the specified minimum thickness
for the desired R-value.
As
a qualified thermal efficiency expert, Kleen Air Services has a
significant investment in equipment, materials, and training to
insure that each job is individually engineered to provide the stated
R-value at the specified thickness for its Rich-R and Climate Pro
loose-fill insulation. If the loose-fill is applied at the minimum
thickness, extensive testing has shown that it will be dense enough
to achieve the specified R-value. This testing enables manufacturers
to label their products accurately, beyond all FTC requirements,
and allow for application variations at the same time. Any home
can benefit from attic insulation. |
