What is an ICF? How can it save energy?
“In a prior life,” says Bill Juhl, 58, tongue in cheek, “I was a meteorologist with 20 years in applied physics. But I got irritated, then angry about poor thermal quality in conventional construction in the 1980s in California. So I set out on a quest, and in the process of building a new house evaluated available building products.”
In his quest he looked at rammed earth, straw bale, light straw clay—pretty much all the alternative construction. “While they offered interesting attributes, such as saving energy,” he says, “they all have big risks associated with them as well. For example, there’s uncertainty about their durability over a long lifecycle.”
And wood, forget it. “Track houses out of wood,” says Juhl, “rarely survive until the end of their mortgage, whereas in Europe, their (non-wood) homes have expected lifetimes of at least 200 years. They think we’re crazy, building out of wood.” Not only that but the quality of the wood has been declining (“It’s horrible compared to even five years ago”), costs are going up (he’ll cite figures for you), and there’s a growing scarcity (“We’re importing it”). “For a builder who wants to build quality construction, it ‘s more difficult and more costly than it used to be.”
What’s left then? Juhl started looking at construction that had well proven its durability. The Roman Coliseum, for example; it was built with concrete, he says, and is still (mostly) standing last time we checked. Frank Lloyd Wright seemed to admire concrete, as he built most of his houses with it. The electric light genius Thomas Edison used concrete to build a home on Long Island in 1908. Then came the clincher: what did the third little pig in the fairy tale build the house that stood up to the wolf out of? Well, okay, it wasn’t concrete, but it was stone”close.
All this convinced Juhl that concrete was worth looking into. What he found impressed him: insulating concrete forms (ICF). “They’re like 4-foot long hollow legos,” he says, made of foam and, once secured in place with rebar, are filled with concrete. Their substantial thermal mass stores heat, on one hand, and their insulating factor repels transmission of heat on the other, thus providing a thermal equivalent of an R50 wall (R9-R17 is more the norm for ordinary houses). This has been corroborated, Juhl says, by independent construction labs. He, himself, was impressed enough that he became a distributor for the international manufacturer of the forms.
His business, started in 2001, is AMVIC-Pacific in Nevada City.
The bottom line, though, is: just how much energy does this system save? He gives the example of two identical houses built side by side. “If all you change is the wall system, the one built with insulating concrete forms uses 40-60 percent less energy over a 12-month period.
“Calculated out over 200 years of life expectancy the house will consume tens of tons less of fossil fuels””not a small thing, he says, when you consider that in the U.S. the largest single source of air pollution is in the providing of energy for conditioning air in buildings.
Noise reduction (75% of what comes through walls), fire proofness, and strength (“It will withstand falling trees, crashing cars, and”yikes”stray bullets”) are some of the other benefits.
Now we get to the bottom, bottom line: what does this Superman
kind of system cost? When comparing it to a minimum code frame construction on a flat lot, the initial cost of the house built out of these forms comes in at about the same to 4% more, which is quickly offset by energy cost savings.
There is just one problem, says Juhl, “Builders aren’t familiar with it.” That’s despite the fact that there are a number of architects and designers here who like working with them, and despite the fact that there are over a hundred of these structures in the county already.
So, to remedy that, the NCCA’s new building will have its shell built of ICF. To do that members of the organization must be trained, and Juhl’s company will do just that, thus catapulting Nevada County to the top of the list of counties in the country that have the most ICF installers. It all happens in a series of classes this spring.
Juhl predicts that ICF will go from specialty product to mainstream in the state in fairly short order. The National Association of Home Builders, he claims, forecasts that in five years 25% of all housing starts nationwide will be ICF in the outer shell.
“We are 100% committed to our builders and owner builders in making sure each and every project is successful,” says Juhl, “so we walk the extra mile. So far, we have a very happy group.”n
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