The ICF Effect

New energy codes, higher fuel prices, and colder winters have all contributed to an increased awareness of energy efficient construction. For consumers and builders, this means a stronger focus on increased "R-value" of the building envelope. Understanding the history of code prescribed R- value will give perspective of this measurement as it is used today.

Prior to the oil crisis in the 1970's, energy was cheap and little focus was placed on insulation, as evidenced by the lack of any insulation in "mid-century" homes. The skyrocketing fuel prices triggered a need for immediate improvements in energy efficiency in homes, and minimum R-values were prescribed as a quick remedy. These values were based on the insulation materials that were typical at the time, measured by the existing hot box testing method1. The resulting R-value is the resistance to heat flow of a given material, measured in a steady state. Of
course, the real world has more variable temperatures, but for the most part this system produced the intended results of increasing insulation requirements for wall assemblies. "The synergy of higher R-value, virtually no air infiltration and thermal mass in ICF assemblies result in performance that simply can't be duplicated with traditional framed assemblies."

For systems such as Insulating Concrete Forms (ICFs), this prescriptive approach does not reflect the true effectiveness of the wall components. If it did, then a frame house with R-19 fiberglass batt insulation would have the same energy performance as an R-19 ICF house, all other things being equal.

However, houses built with ICF exterior walls typically require 44% less energy to heat and 32% less energy to cool than comparable frame houses.2 What is the difference? We call it the ICF Effect.

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