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Inadequate
insulation is a common culprit for high energy bills and
discomfort in older homes, but it can also present an area of
weakness in newer homes as well.
Though
installing more insulation will likely have a positive impact on
energy consumption, the degree of impact will vary from home to
home. Other factors include the home's age, living habits of
family members, outdoor climate, the efficiency of heating and
cooling systems, fuel type and the construction of the building.
When shopping
around for insulation and getting quotes from contractors,
familiarize yourself with the insulation or “R-value” (in metric,
this is the "RSI"). This term is your ticket to understanding the
impact of insulation on energy use and will help you determine
what material to buy and how much.
Thermal
resistance
R-value refers
to thermal resistance to heat flow - the higher the R-value, the
greater the insulating effectiveness. The type of material, its
thickness and density constitute the R-value. Compare different
types of insulation by the R-value per inch of thickness.
You can make an
educated guess of the current R-values in your walls by knowing
your home's construction date and the codes in place at that time.
Typically, homes built before 1980 (2x4 wall construction) have
R12 insulation or less in the walls, while those built after 1980
(2x6 wall construction) have R20 insulation.
If your home is
built before 1950, however, extremely low R-values could be the
result of poorly performing insulation, like wood shavings (if
there's any insulation in the walls at all.)
If you suspect
the entire home requires additional insulation, but you’re working
with limited budget and timelines, address the major area of heat
loss: the basement and attic.
A good place to
start is in the attic. Usually it’s the easiest place to access
where you can visually examine the depth and type of insulation.
Once you’ve
decided where to insulate) and have determined the R-values you
require), it's time to think about what type of insulation to buy.
There are
several forms of insulation to choose from with varying R-values
and thickness. Certain types of insulation are more effective in
reducing heat flow for various applications, so compare carefully
when shopping. You can install some insulation yourself, while
others have to be installed by a contractor.
Talk to your
local building supply store representative or renovation
contractor about the various applications.
Batts (or blankets):
made of glass
fibre or mineral wool; R-values between 2.8 and 3.7 per inch.
Loose-fill
insulation:
created with
various loose fibres: glass fibre (R3.0-R3.7), mineral wool
(R2.8-R3.7) or cellulose (R3.0-R3.7). All types typically blown in
place by a professional.
Rigid board
insulation:
ranges from
low-density to high density with fluctuating R values between 3.6
and 7.7 per inch; common for exterior applications.
Spray foam
insulation:
must be applied
professionally using special equipment to meter, mix and spray
into place; varying materials; R-value between 3 and 6.8 per inch.
Consider selecting an insulation less dense than the existing
material if you plan to add to existing insulation. The current
material will otherwise be compressed, substantially lowering its
R-Value.
Air leaks
Before
insulating, be sure to control air leaks and prevent moisture
build-up so the material will work properly over the life span of
the house. Air leaks that are overlooked will channel unwanted
heat flow through the walls, floors and attic. Once humid air
traversing these passageways becomes trapped inside the
insulation, the material and structure can get permanently
damaged.
Once the new
insulation is well-positioned, it's not uncommon that the money
saved through lower energy bills will pay for the insulation
within a few years. These savings will continue throughout the
duration of ownership, along with improved comfort levels and an
increased resale value of your home. |
