Heating and cooling a home accounts for as much as 50
percent of a household utility bill. Stopping energy leaks with proper
insulation can cut heating and cooling costs by as much as 20 percent, while
improving overall comfort in the home. When selecting an insulation and
installation strategy, it is necessary to first understand how a building's
insulation impacts heating and cooling. Location, structural specifications,
and budget are key factors to selecting the right insulation.
How Insulation Works
A dynamic energy force, heat seeks equilibrium and will
always flow from warm areas to cooler, until there is no temperature
difference. Its three primary means of movement are convection, conduction, and
radiation.
Convection describes the movement of heat through liquid and
gas, while conduction is the same movement through solid materials. When people
say that "heat rises," they are describing one of the most common
behaviors of convective heat - that cooler, denser air displaces warmer,
lighter air, causing it to rise. Radiant heat travels in a direct line,
transmitting heat directly to objects in its path. The light and heat
transmitted by sunshine is an example of radiant heat.
Effective insulation of a home will deal with all three of
these transmission properties, with specialization based on particular location
characteristics. For example: when looking to cut cooling costs where persistent
southern exposure exists, creating barriers to the natural, radiant heat is
key. Most commonly, though, it will involve stopping energy leaks in the forms
of conductive heat loss or gain. Radiant barriers, such as reflective panels on
a roof or planted shade-generating trees, are some common methods of insulating
from external radiant heat sources.
Types of Insulation
Insulation is graded based on the insulating material's
effectiveness in stopping heat flow. This thermal resistance is known as an
R-value-the higher the R-value, the greater the insulation. The total R-value
of an installation is based on the thickness and layering of insulating
materials used. The more layers installed, the greater the R-value, and the
greater the energy savings.
Optimal installation targets a structure on multiple fronts.
While bulky, heavy insulation-known as bat and roll blanket, after the common
practice of unrolling large spools of the material by hand-is most popularly
used in large, open spaces of a building, such as the roof or crawlspaces.
Spray foam has traditionally been utilized for filling smaller, more specific
spaces, although recent advances in foam technology has led to an increase in
demand.
Considered one of the best methods for insulating a home,
spray foam has been found to insulate twice as well as other types. Spray
insulation's major advantage is its ability to expand to fill spaces without
creating air pockets or open spaces. Additionally, spray foam technology has
evolved to include open and closed cell foam compositions and environmentally
friendly options. Spray foams are also considered to be more mildew and mold
resistant than traditional insulation, and they provide a better noise barrier.
