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Building Energy-Wise Homes with ICFs
ICF walls are the "Ferrari"
of exterior wall systems for cutting home heating and cooling
By Anne Balogh, ConcreteNetwork.Com Feature Writer
If Richard Rue, CEO of Energy Wise Systems, Mansfield, Texas,
had his way, most new homes being built in the country today
would have exterior walls constructed with insulating concrete
forms. "You can heat and cool three ICF houses for every
one house thats typical 2x4 wood-frame construction with fiberglass
insulation," he claims.
Energy Wise is a mechanical engineering company that specializes
in energy-efficient construction by designing the HVAC system
to work in harmony with a structures thermal envelope. The
company hopes to foster national energy conservation through
the efficient and sustainable use of natural resources.
Energy Wises customers--which include builders, homeowners,
and even building-material distributors--receive a computerized
energy analysis of their building plans. This six-page analysis
accurately projects the structures heating and cooling consumption,
- How much the property owner can expect to save in heating
and cooling costs over a period of time by building a structure
according to Energy Wises recommendations.
- What percentage each component in the structure is contributing
to total energy usage.
- What the average energy consumption will be per month.
- What size heating and cooling system is needed to do
the job most efficiently.
"Its very important to correctly size the mechanical
system in an energy-efficient structure so you don't create
problems," stresses Rue. For example, if a homes air
conditioner is oversized, the unit will short cycle and it
wont run for long enough periods of time to properly dehumidify
the interior space.
Its all about airtightness
One of the major factors in achieving top energy efficiency
is airtightness. "Consider an airplane," says Rue.
"When flying at 35,000 feet, the plane is exposed to
outside air temperatures of -50 F, with wind chills as low
as -150 F. The shell of a plane is typically just 2 inches
thick, but passengers don't freeze because its airtight. Once
a structure is airtight, it takes very little energy to keep
it at a certain temperature."
Thats why Rue often recommends the use of ICFs, calling them
the "Ferrari" of exterior wall systems. "About
80% of all air leakage through a house is through the walls,"
says Rue, "and ICFs eliminate that leakage." He
has worked with various ICF manufacturers to help them maximize
the energy efficiency of structures built with their systems.
Because ICFs completely encapsulate concrete in two layers
of foam insulation, they provide a nearly continuous barrier
against air infiltration. The concrete walls also have a high
thermal mass, which shields the home interior from outdoor
temperature extremes, reducing peak and total heating and
Growing market for concrete homes
Rue has seen a phenomenal increase in the demand for ICF
homes over the past few years, as more and more homeowners
have become aware of the savings in energy costs possible
with concrete versus wood-frame construction. The Portland
Cement Association predicts that ICFs will be the fastest
growing method of concrete construction for the single-family
residential market in the next 2 years. PCA Market Research's
2000 Homeowner Report, which is summarized on PCAs Concrete
Homes Web site, www.concretehomes.com, says that the majority
of homeowners are aware of concrete homebuilding systems.
And from 1998 to 2000, awareness of ICFs doubled, jumping
from 22% to 41%.
Rue admits that an ICF home may cost a bit more initially
than a comparable wood-frame structure, but the monthly savings
in utility costs will more than make up for the additional
outlay. "Ive never had a house that was built based on
our recommendations that wasn't in a positive cash flow from
day one," says Rue.
Energy savings guaranteed
Rue has so much confidence in the Energy Wise analysis that
he guarantees a structures monthly heating and cooling consumption
for the first 2 years after occupancy, and he even insures
"If you build a new house the way we design it, we guarantee
the utility rates aren't going to exceed 3 to 5 cents per
square foot," explains Rue. "With the national average
at 10 cents per square foot, thats a savings of 50% to 70%."
Rue adds that Energy Wise is one of only a few companies
in the country to offer such a guarantee and the only company
to insure it. During the 2-year guarantee period, Energy Wise
will monitor the structures monthly heating and cooling consumption.
If the consumption level exceeds the guaranteed amount, an
insurance company will rebate the difference back to the homeowner.
Considering the total savings in energy costs that are possible,
the cost of the energy analysis is very reasonable, starting
at $250 for a home up to 2999 square feet.
Other strategies for saving energy
Although ICF construction is one of the best ways to minimize
air penetrations into a home, builders must take other measures
to ensure maximum airtightness. "People think that just
building a home with ICF walls covers it in terms of energy
efficiency, but it doesn't," says Rue. He gives the following
common-sense tips for reducing air infiltration:
- Caulk every place in the building framework where air
could possibly enter, such as around window and door frames,
sill plates, and plumbing and electrical penetrations.
- Avoid the use of recessed, or canned, lights. "One
of these lights represents 1 square foot of uninsulated
attic space, and 20 of these lights represents a door open
in the attic all the time," says Rue. When a homeowner
insists on recessed lights, Rue recommends using a brand
that can be insulated and has airtight rings.
- Use "thermally broken" windows, those with
wood or vinyl frames as opposed to aluminum, which conducts
heat and cold. In northern states, use low-E glass, which
reduces heat loss in the winter and heat gain in the summer.
- Avoid the use of sliding glass doors. Rue says that the
gaskets on these doors don't seal properly, so they allow
a lot of air infiltration. As an alternative, he recommends
installing double atrium doors that swing open only on one
Lower total cost of ownership
Some home buyers may be reluctant, at first, to pay more
upfront for an ICF home. But by teaming up with an energy-analysis
firm such as Rues, concrete homebuilders can convincingly
market the lower total cost of ownership for an ICF house.
"With the way utility costs are going up, the wood-frame
houses being built today will, in 20 years, have monthly utility
payments that exceed the monthly house payment," says
Rue. That wont happen with a properly constructed ICF house,
especially one that comes with an insured guarantee that the
monthly energy costs will not exceed a certain amount.