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Energy Efficient ICFs
Taken from ICF Builder Magazine
Insulated Concrete Form R-Value Insulated Concrete Forms
(ICFs) are rapidly gaining popularity as an alternative building
material. As energy prices climb, ICFs are set to become even
more popular. Most homeowners save between 30% to 50% on heating
and cooling costs when compared to regular stick-frame construction.
A recent study by the Portland Cement Association (PCA) found
that the ICF homes used 44% less energy to heat and 32% less
energy to cool than comparable frame houses. That means a
typical 2,000-sq.-ft. ICF home in the central U.S. would save
$200 in heating costs and $65 in cooling costs each year.
“All the test data currently available shows that ICF
construction has the best combination of energy efficiency
and strength for building external walls,” confirms
Ann Crocker, co-owner of Energy Smart Solutions, a Dallas-based
residential contractor. “What we have found is that
the homeowner will save at least two-thirds on their energy
costs compared to wood frame 2x4 construction with fiberglass
batt,” says Crocker.
ICFs work to conserve energy in five different ways.
Smaller HVAC Units: “To maximize your
energy savings, it’s important to ensure the HVAC system
is right-sized for the home,” says Richard Rue, founder
of Energy Wise Structures. In most cases, that means buying
a unit that is significantly smaller, cutting construction
costs by $500 to $2,000.
Rue confirms this. “Many times a 2,000 sq. ft. ICF
house located in a Sun Belt state may need only 1-1/2 tons
of cooling capacity, instead of the 4 tons needed for a wood-frame
structure of equal size,” he says.
Higher Rated R-Values: “R” is
“R-Value” stands for thermal resistance, and the
higher the R-Value, the better the wall is at stopping the
flow of heat. Homes built using traditional frame construction
typically have exterior walls rated between R-13 and R-19.
ICF walls, on the other hand, have an insulation value of
R-22 or R-26. A frame wall would need to be a full 12 inches
thick to achieve a similar rating.
Airtight Construction: “Tested R-Values,”
however, don’t necessarily reflect real-world performance.
For instance, laboratory tests don’t consider the level
of airflow through the wall, which is one reason why ICF walls
usually perform even better than lab tests indicate.
Anyone who has lived in a drafty house knows how quickly
a room can cool when a winter storm howls outside. For the
past decade or so, homebuilders have tried to reduce air infiltration
by covering exterior walls in a layer of paper-like “homewrap,”
which has partially addressed the issue of air infiltration.
ICF walls, on the other hand, are virtually airtight. Even
hurricane-force winds can’t force their way through
four to six inches of solid concrete.
Thermal Mass: Even a modest ICF home uses
dozens of yards of concrete, and that weight helps moderate
temperature swings. The secret is that the walls take hours
to heat up—even in the hot summer sun. And when the
sun sets and temperatures drop, the stored-up heat keeps the
interior pleasant through much of the night.
Homeowners report that once their ICF homes reach room temperature,
it takes very little energy to keep them there. For example,
one beautiful 9,000 sq. ft. home in Central Minnesota averages
less than $70 per month in heating and cooling costs.
Conducts Ground Temperature: In most parts
of North America, the ground stays a constant 50o to 55o Fahrenheit
a few feet below the surface. Concrete actually conducts thermal
energy fairly well, and in the winter months, it absorbs this
extra heat from the earth and transfers it into your home.
During the summer, it wicks that coolness from the ground
and transfers part of it into the structure.
Admittedly, ground temperature conduction is probably a minor
factor in keeping energy bills to a minimum, but when combined
with the other four elements mentioned here, the five make
a powerful argument for using ICFs above grade. No other alternative
building technology can offer the high R-values, airtight
construction, and thermal mass of ICFs.
Incredibly, the cost of living in an ICF home is no higher—and
may be cheaper—than living in a regular house. Here’s
the math:
The Insulating Concrete Forms Association (ICFA) estimates
that ICFs cost 3% to 5% more than frame building. That’s
about $10,000 for a $250,000 house. Financed with a conventional
30-year loan at 6.5%, it will add $62.55 to the monthly mortgage.
However, because the homeowner will be saving at least that
much on energy bills, the actual monthly cash outlay is less.
In other words, when energy costs are considered, it’s
actually less expensive to live in an ICF house. All of the
other benefits—like quiet interiors, less maintenance,
and disaster-proof walls—are added bonuses at no extra
cost. Crocker says, “A traditional builder sells what you
can see: kitchens, master bedrooms, all the elements that
have nothing to do with the structure. The value we offer
is in the structure itself, and what it will do from day one
for the occupant.” |
