ICF Advantages for the Home Owner

Greater Comfort and Lower Energy Bills
Energy savings and comfort are built into every ICF system. ICFs start with a high R-value. Five inches of ASTM C 578 polystyrene foam insulation, combined with a six inch concrete wall - a typical ICF system - is rated above R-37. But that's not all! Air infiltration in an ICF home is minimal due to the continuous air barriers provided by the foam insulation and the concrete. Likewise, there are no convection currents within wall cavities. The concrete walls of an ICF home have high thermal mass, which buffers the interior of a home from the extremes of outdoor temperature during every 24-hour cycle. This reduces both peak and total heating and cooling loads. This combination of high R-values, low air infiltration and high thermal mass is believed to account for an amazing 25 - 60% energy savings of ICF versus wood framed homes.

We believe that the energy savings of ICF homes result from three factors: a higher R-value, which reduces heat conduction through the wall; a lower air permeability, which reduces air infiltration; and a greater thermal mass, which partially buffers the interior from outdoor extremes in temperature. The calculated R-values of ICF walls range from about 17 to 23. Recent studies at Oak Ridge National Laboratory confirm the high R-value of ICFs (see "Wall R-Values that Tell It Like It Is," HE Mar/Apr '97, p. 15). In contrast, the tests showed that typical finished 2 x 4 frame walls with R-11 insulation were effectively about R-9. This is mainly
because the studs act as a thermal bridge, compromising the insulation. Since ICFs have about twice the R-value of frame walls, we can expect conduction losses to be about half as much. When the home is being heated, wall conduction losses run around 25%, so we can expect ICFs to save about 12%-13% of heating energy use.

Blower door tests on ICFs from a variety of sources have yielded estimated air changes per hour (ACH) that range from about 0.11 to 0.5. Large-sample surveys of new frame houses yield an average of about 0.5. Thus ICF walls appear likely to cut losses from air infiltration by
almost half as well. Since infiltration losses account for 20%-40% of total thermal losses, the reduction in infiltration could reduce energy consumption by almost another 10%-20%.
Thermal mass in a wall absorbs large amounts of heat without the temperature of the wall changing rapidly. This buffers the interior somewhat from sharp swings, leveling out the highs and lows of the day. That reduces energy consumed, especially when the average daily outdoor temperature is around 70°F. In such circumstances thermal mass prevents exterior temperature extremes from being noticed inside the house. Engineering simulations of thermal mass effects suggest that buildings with well insulated high-mass walls (like ICF walls) will tend to consume 4%-8% less conditioning energy than well insulated low-mass walls, the exact amount depending on the local climate.


Peace and Quiet
New ICF homeowners almost always remark on how unbelievably quiet their new house is, compared with their old stick-built home. They expect the new-found comfort and energy efficiency, but the peace and quiet - the protection from the outside noise - never fails to surprise and delight them.

In sound transmission tests, ICF walls allowed less than one-third as much sound to pass through as do ordinary wood frame walls with fiberglass. With double-glazed windows in ICF walls and beefed-up roof insulation, you will rarely hear street noises or airport traffic.

Solid and Lasting Security
The high-mass walls of an ICF home not only give it an remarkable solid feel, but they also make it safer for the family. And make it a remarkably solid and secure investment, too. Concrete homes have a proven track record of withstanding the ravages of hurricanes, tornadoes and fires, when all the stick-built houses around them are in ruins. In fire wall tests, ICFs stood exposure to intense flame without structural failure longer than did common frame walls. The polystyrene foam used in most ICF forms is treated so it will not support combustion. Also, tests show that its tendency to transmit an outside flame source is less than that of most wood products. (Many insurance carriers are now offering a discount on a home owner's policy for an ICF home.)

Less Repair and Maintenance
With ICF homes, the equation is simple. No rot = Less repair and maintenance. Neither polystyrene nor concrete will ever rut or rust. Concrete can even be exposed to the elements for centuries with few ill effects. Reinforcing steel, buried deep inside and protected by concrete's alkalinity, does not corrode.

A Healthier Home and Environment
Building with ICFs is healthier for the environment in a number of ways: by minimizing the lumber used, by reducing the amount of waste generated on the construction site, lowering energy requirements for heating and cooling and through concrete's use of recycled products like fly-ash and ground granulated blast furnace slag.

ICF homes provide a healthy indoor environment, too. Nothing held within ordinarily emitted by an ICF wall is toxic. The measurement of air contents of actual ICF houses shows an almost complete absence of any emissions.