Energy

How do we know all this ?

The energy savings estimates come from a study of single-family houses spread across the U.S. and Canada. Researchers gathered data on 58 houses in all. Half had exterior walls constructed with concrete using ICFs made of expanded polystyrene (EPS) or extruded polystyrene (XPS) foam. The other half were neighboring houses with walls constructed of wood frame. All houses were relatively new (less than 6 years old) and built with modern methods.

The researchers compared the energy bill of each concrete house to its frame counterpart, carefully correcting for important differences to get an "apples-to-apples" comparison.

Estimates of equipment savings are actual numbers reported by contractors that build ICF houses.

Where do the savings come from ?

Insulating values for ICF walls using polystyrene foam are R-24, compared to wood frame or concrete block at R-9 to R-15. So ICF walls are expected to cut the conduction losses through foundation and above-grade walls by about half. And ICF walls are tighter. In tests, ICF houses averaged about 1/4 as much infiltration (air leakage) as frame.

But ICF walls do more than cut down on the biggest types of energy loss. The concrete gives them the heat-absorbing property, "thermal mass". This is the ability to smooth out large swings in temperature. It keeps the walls of the house a little warmer when the outdoor temperature hits its coldest extreme, and keeps the house a little cooler when the outdoor temperature is hottest. The walls themselves "add back" heat or cooling to the house when it needs them most. This contributes about 6% of the needed energy to the house for free.

Reduced equipment costs result from the energy savings. Since the energy needed is less, the furnaces and compressors that heat and cool can be smaller. And the more the energy savings, the greater the possible reduction in equipment size-and the equipment cost.

What's the bottom line ?

In planning a new house you can estimate that building the walls of concrete using ICFs will save you hundreds of dollars per year in energy costs. Savings will vary in different regions of the country and with the size of the home. Heating savings are highest in cold climates, and cooling savings highest in warm climates.

You may also save hundreds or thousands of dollars in construction costs for heating and cooling equipment. Talk to your sales associate for estimates.