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Building Energy-Wise Homes with ICFsICF walls are the "Ferrari" of exterior wall systems for cutting home heating and cooling costs
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, showing:
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 cooling needs.
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 that guarantee.
"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 side.
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.
Anne Balogh writes feature articles each month for The Concrete Network (www.concretenetwork.com). She is a freelance writer based in Glen Ellyn, Ill., and a former editor of Concrete Construction magazine.