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January 18, 1998
For Immediate Release
For more information, contact Jennifer Grover or Bruce McIntosh at PCA (847) 966-6200.
Homeowner Survey Reveals 44% Heating and 32% Cooling Energy Savings with ICFs
Statistical comparison indicates that using insulating concrete forms (ICFs) instead of conventional wood frame will reduce the amount of energy consumed for heating by about 44%, and for cooling by about 32% on average. A new study measured ICF homes constructed using pure foam systems (no foam-cement composites).
Apples to apples approach
The new study, conducted by Dr. Pieter VanderWerf of the Boston University School of Management and sponsored by the Portland Cement Association, analyzed statistics from 58 homes—29 ICF and 29 frame. “We wanted to approach this study as an ‘apples to apples’ comparison,” says VanderWerf. “So we paired each ICF house with a comparable frame house.”
Criteria for the paired houses was that they be 1) nearby, 2) of similar square footage, and 3) new construction (less than six years old). VanderWerf also adjusted the energy consumption of each house to control for differences in size, design, foundation, number of occupants, thermostat settings, and HVAC equipment.
The corresponding estimated dollar savings averaged about $221 per year for heating energy and $89 for cooling energy.
“The percentage energy savings showed no discernible relationship to local climate,” says VanderWerf. “That is, it was impossible to detect that the percentage of either heating or cooling saved went up or down appreciably in warmer (or cooler) climates. We tentatively concluded that these rates of savings should be fairly constant, regardless of location.”
This result implies that absolute heating savings will be higher in cold climates (Minneapolis: $342 per year for a 2000 square foot home) than in warm ones (Dallas: $100). Projected cooling savings are higher in warmer climates ($108 in Dallas, versus $34 in Minneapolis). “The methods we used to estimate dollar savings are conservative, especially for cooling,” says VanderWerf. “Actual dollars saved for cooling are probably more than we estimate, but we don’t have the data to pinpoint how much.”
Something to talk about
Responses to open-ended questions showed that most people like their new homes regardless of type of construction. But the reasons they gave were quite different.
The ICF owners most often cited functional advantages resulting from ICF walls: comfort (including evenness of temperature and low air infiltration), sound reduction, energy efficiency, and solidity/strength. “It’s extremely quiet, with low utility bills,” one person told surveyors. “I figure I pay half of what others pay with similar square footage.”
Other ICF home owners liked their low utility bills, “It has low utility costs,” said another concrete home owner. “Our highest bill in a month was $110, in summer [in Texas]. Our neighbors hit $200-300 in August and September. [Our house] holds its temperature better once it is at the right temperature.”
Owners of wood frame homes most often cited advantages that accrue to new homes regardless of their construction: location, floor plan, and inclusion of the owner’s preferred features.
“These differences in qualitative responses suggest that frame homeowners saw little advantage to their new houses beyond the features one might expect in any new house,” says VanderWerf. “Not many of the owners of frame homes considered it superior construction.”
In contrast, ICF owners were impressed by advantages of their new houses attributable to the superior construction of the walls.
Other Implications
Interviews uncovered some possible impacts of ICF construction that have important energy implications not picked up by the energy analysis. Several ICF owners with unheated basements commented that their basements were about as warm in winter as their conditioned living space upstairs. They felt that when they finished their basements, they could avoid enlarging their heating systems or consuming more fuel to condition them.
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