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Heat flows
naturally from a warmer to a cooler
space. In the winter, this heat flow
moves directly from all heated living
spaces to adjacent unheated attics,
garages, and basements, or to the
outdoors; or indirectly through interior
ceilings, walls, and floors--wherever
there is a difference in temperature.
During the cooling season, heat flows
from outdoors to the house interior. To
maintain comfort, the heat lost in
winter must be replaced by your heating
system and the heat gained in summer
must be removed by your air conditioner.
Insulating ceilings decreases this heat
flow by providing an effective
resistance to the flow of heat.
Insulation is rated in terms of thermal
resistance, called R-value, which
indicates the resistance to heat flow.
The higher the R-value, the greater the
insulating effectiveness. The R-value of
thermal insulation depends on the type
of material, its thickness, and density.
In calculating the R-value of a
multi-layered installation, the R-values
of the individual layers are added.
Installing more insulation in your home
increases R-value and the resistance to
heat flow.
The effectiveness of an insulated wall
or ceiling also depends on how and where
the insulation is installed. For
example, insulation which is compressed
will not give you its full rated
R-value. Also, the overall R-value of a
wall or ceiling will be somewhat
different from the R-value of the
insulation itself because some heat
flows around the insulation through the
studs and joists. That is, the overall
R-value of a wall with insulation
between wood studs is less than the
R-value of the insulation itself because
the wood provides a thermal
short-circuit around the insulation. The
short-circuiting through metal framing
is much greater than that through
wood-framed walls; sometimes the metal
wall's overall R-value can be as low as
half the insulation's R-value. This is
why the most efficient way to insulate
is your attic. |
(559) 323-4113
LICENSED, BONDED, AND INSURED |
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