http://www.greenintegrateddesign.com/blog/getting-to-know-radiant-barriers
The purpose of a radiant barrier is to reduce summer heat
gain and reduce cooling costs. This is achieved by installing the highly
reflective material, normally in your attic, so that it can reflect the radiant
heat rather than absorbing it.
A radiant barrier’s effectiveness is dependent on both the
type of radiant barrier and the proper installation. The Oak Ridge National
Laboratory estimates the air-conditioning cost savings can range from about
$150 annually for very hot climates to only $40 for cold climates and
installing the barrier incorrectly or choosing the wrong product can prevent
you from reaping those savings. Some consumers end up disappointed with the
effectiveness of their radiant barrier and this is mostly because of improper
installation and poor choice in product so it’s important to do your research.
It is best to use a certified installer but if you choose to
do the installation yourself, carefully study and follow the manufacturer’s
instructions and safety precautions and check your local building and fire
codes. The reflective insulation trade association
also offers installation tips.
The most important decision in the process of installing a
radiant barrier in your home is the product that you choose to invest in. Radiant
barrier paint, radiant barrier chips and radiant barrier foil are the three
types of radiant barriers. We do not
support radiant barrier paint or radiant barrier chips but do support the use
of radiant barrier foil.
Radiant barrier paint
Radiant barrier paint is meant to be a paint that is
reflective and can simply be painted onto a surface to reflect radian heat.
There are a few flaws to the product. Radiant barrier paint can be diluted in
the field with water and will lose its effectiveness when applied. I’ve seen many houses where the radiant paint
looks more like gray paint rather than a reflective paint, which is a sign of
dilution. In fact, radiant barrier paint is technically not even a radiant
barrier, because its reflectance is only 75%. Radiant barrier paints also has lower performance standards with higher
emittance values and lower reflectance values than traditional radiant barrier
foils.
Radiant barrier chips
Radiant barrier chips are flakes of a reflective material
that is scattered throughout the attic. The problem with radiant barrier chips
is that installers usually do not install them with enough density to cover the
entire surface area of the attic. The chips need to be several layers deep and
must be evenly spread which bring us to the other issue of the chips being very
easily moved.
Radiant barrier foil/sheathing
Radiant barrier foil is a sheet or board that is covered
with reflective material. The radiant barrier foil comes either in single or
double sided. Some foil may be breathable with ventilation holes. Some radiant
barrier foil may also have a foam core with some insulation value to it. This
type of radiant barriers, meeting certain criteria, can in fact be classified
as insulation under the EPA, qualifying them as ENERGY STAR products. We support this method of radiant barrier
because it’s the most effective, maintenance free, long lasting, and reliable.
