Properly insulating your home will not only help
reduce your heating and cooling costs but also make
your home more comfortable. Here you'll find the
following information:
How Insulation Works
You need insulation in your home to provide
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.
Adding Insulation to an Existing Home
Unless your home was specially constructed for
energy efficiency, you can usually reduce your
energy bills by adding more insulation. Many older
homes have less insulation than homes built today,
but adding insulation to a newer home may also pay
for itself within a few years.
To determine whether you should add insulation, you
first need to find out how much insulation you
already have in your home and where.
A qualified home energy auditor will include an
insulation check as a routine part of a whole-house
energy audit. An energy audit will also help
identify areas of your home that are in need of air
sealing. (Before you insulate, you should make sure
that your home is properly air sealed.)
If you don't want an energy audit, you need to
find out the following:
•Where your home is, isn't, and/or should be
insulated
•What type of insulation you have
•The R-value and the thickness or depth (inches) of
the insulation you have.
If you live in a newer house, you can probably find
out this information from the builder. If you live
in an older house, you'll need to inspect the
insulation yourself if you don't want an energy
audit.
Inspecting and Evaluating Your Insulation
•Check the attic, walls and floors adjacent to
an unheated space, like a garage or basement. The
structural elements are usually exposed in these
areas, which makes it easy to see what type of
insulation you have and to measure its depth or
thickness (inches).
• Inspect the exterior walls using an electrical
outlet:
1.Turn off the power to the outlet.
2.Remove the outlet cover and shine a flashlight
into the crack around the outlet box. You should be
able to see if there is insulation in the wall and
possibly how thick it is.
3.Pull out a small amount of insulation if needed to
help determine the type of insulation.
4.Check outlets on the first and upper floors, if
any, and in old and new parts of a house. Just
because you find insulation in one wall doesn't mean
that it's everywhere in the house.
• Inspect and measure the thickness (inches) of any
insulation in unfinished basement ceilings and
walls, or above crawl spaces. If the crawl space
isn't ventilated, it may have insulation in the
perimeter wall. If your house is relatively new, it
may have been built with insulation outside the
basement or foundation walls. If so, the insulation
in these spaces won't be visible. The builder or the
original homeowner might be able to tell you if
exterior insulation was used.
• Once you've determined the type of insulation you
have in these areas and its thickness (inches), see
the U.S. Department of Energy's online Insulation
Fact Sheet for how to determine the R-values of
insulation previously installed in your home.
Determining Recommended R-Values When you find out the R-values of your
insulation either from an energy audit, the home
builder, or your own inspection, you can then use
the U.S. Department of Energy's Zip-Code Insulation
Program to determine how much insulation you should
add and where to achieve the recommended insulation
levels for maximum energy efficiency.
Estimating Costs and Payback The Zip-Code Insulation Program provides
insulation cost estimates and a rate of return on
your investment. Also see our information on
estimating the payback period of additional
insulation.
Deciding What Type of Insulation to Add If you decide to add insulation to your home,
review our information on the types of insulation
available to help you decide what type to use and
where.
Selecting Insulation for New Home Construction
Your state and local building codes probably include
minimum insulation requirements, but to build an
energy-efficient home, you may need or want to
exceed them. For maximum energy efficiency, you
should also consider the interaction between the
insulation and other building components. This is
called the whole-house systems design approach.
To properly insulate a new home, you first need to
know where you need to insulate and the recommended
R-values for each of those areas. Use the U.S.
Department of Energy's Zip-Code Insulation Program
to determine where you need to insulate and the
recommended R-values based on your climate and type
of heating and cooling system, etc. The program also
will provide cost estimates and a rate of return.
Once you know where you need to insulate and the
recommended R-values, review our information on the
types of insulation available to help you decide
what type to use and where.
Before you insulate a new home, you also need to
properly air seal it and consider moisture control.
Your state and local building codes probably include
minimum insulation requirements, but to build an
energy-efficient home, you may need or want to
exceed them. For maximum energy efficiency, you
should also consider the interaction between the
insulation and other building components. This is
called the whole-house systems design approach.
To properly insulate a new home, you first need to
know where you need to insulate and the recommended
R-values for each of those areas. Use the U.S.
Department of Energy's Zip-Code Insulation Program
to determine where you need to insulate and the
recommended R-values based on your climate and type
of heating and cooling system, etc. The program also
will provide cost estimates and a rate of return.
Once you know where you need to insulate and the
recommended R-values, review our information on the
types of insulation available to help you decide
what type to use and where.
Before you insulate a new home, you also need to
properly air seal it and consider moisture control.
