Why do I need
insulation?
Insulation provides resistance to heat
flow. The more heat flow resistance your insulation provides, the
lower your heating and cooling costs.
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,
basements, and even to the outdoors. Heat flow can also move
indirectly through interior ceilings, walls, and floors—wherever
there is a difference in temperature. During the cooling season,
heat flows from the outdoors to the interior of a house.
To maintain comfort, the heat lost in the
winter must be replaced by your heating system and the heat gained
in the summer must be removed by your cooling system. Properly
insulating your home will decrease this heat flow by providing an
effective resistance to the flow of heat.
An insulation's resistance to heat flow is
measured or rated in terms of its thermal resistance or R-Value. (A
Consumer's Guide to Energy Efficiency and Renewable Energy)
What is "R
Value"?
An R-value indicates an
insulation's resistance to heat flow. The more heat flow resistance
your insulation provides, the lower your heating and cooling
costs. The higher the R-value, the greater the insulating
effectiveness.
The R-value depends on the type of
insulation and includes its material, thickness, and density. When
calculating the R-value of a multilayered installation, add
the R-values of the individual layers. Installing more insulation in
your home increases the R-value and the resistance to heat flow.
The amount of insulation or R-value you'll
need depends on your climate, type of heating and cooling system,
and the section of the house you plan to insulate.
(A
Consumer's Guide to Energy Efficiency and Renewable Energy)
How many inches
of insulation should be in my attic?
There are several factors that are used to
determine the thickness of the insulation needed to provide an
adequate amount of heat flow resistance in a specific home attic.
Some of those considerations would be climate, local environment,
type of construction, type of insulation and method of installation.
For example, in our service area in the Southeast, you should have
12.5 inches of fiberglass insulation to provide a R-Value of 30,
which should provide the comfort and efficiency you need in the
typical Southeastern attic.
(A
Consumer's Guide to Energy Efficiency and Renewable Energy)
What is the
difference between open and closed cell Spray Polyurethane Foam?
Low density, open cell SPF refers
to a generic spray polyurethane SPF applied to a substrate as a
liquid and expands about 100-150 times its original volume to form a
semi-rigid/flexible, non-structural SPF insulation. The SPF has an
R-value around 3.5 per inch and typically uses water as the blowing
agent.
Medium density, closed cell SPF
used in interior applications typically refers to generic spray
polyurethane foam applied as a liquid to a substrate and expands
about 35 to 50 times its original volume to form a rigid, structural
SPF. The SPF has an R-value of around 6.0 per inch (aged R-value)
and uses high R-value blowing agents.
Both products are excellent air barriers
in buildings, provide great insulation, can assist in the control of
condensation within buildings and have great environmental benefits.
(Spray
Polyurethane Foam Alliance FAQ)
How much would
increasing my insulation reduce my energy costs?
Heating and cooling ("space conditioning") account
for 50 to 70% of the energy used in the average American home. About
20% goes for heating water. On the other hand, lighting and
appliances and everything else account for only 10 to 30% of the
energy used in most residences. Unless your home was constructed
with special attention to energy efficiency, adding insulation will
probably reduce your utility bills. Much of the existing housing
stock in the United States is not insulated to the best level. Older
homes are likely to use more energy than newer homes, leading to
very high heating and air-conditioning bills. Even if you are
building a new home, choosing upgraded insulation will save
enough money in reduced utility bills to pay for itself within only
a year or two, continue to save you
money for as long as you own the home, and increase the resale value
of your house.
(Insulation:
The Basics)
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