ICF stands for Insulated Concrete Form. ICF's are a rapidly growing aspect of both residential and commercial structures due to a combination of their many benefits; which include:
Ultra Energy Efficient
Significantly safer
More comfortable
Healthier air
Silent
And best of all, cost-effective!
ICF's are very efficient in three important areas: High "whole wall" r-values, reduced air infiltration, and thermal mass effect. The combination of these three things is simply unattainable in any other one-step process; and is difficult and expensive to duplicate even with a number of steps. Let's look at each of these in turn.
High "whole wall" r-values. By "whole wall", we mean the average r-value of the entire wall, not the r-value of the insulation as is normally mentioned.
A typical stud wall is 25% solid wood; over and beside windows and doors, corners, top and bottom plates, etc. Wood has an approximate r-value of 1 per inch. This means your typical 2x6 wall with r-19 insulation has a whole wall r-value of 16.
A typical brick and block combination wall with 2" Extruded polystyrene has a whole wall r-value of 14.
An ICF wall is unbroken by any studs, so you get the true r-value of the insulation. Depending on the form chosen, this can be either r-22, r-23, r-24, or r-28.
With an ICF wall, the heat cannot take a short circuit through the studs; and the whole wall r-value is significantly higher, up to 267% higher than even the best insulation in a 2x4 wall, up to 75% higher than even the best insulation in a stud wall, and up to 200% higher than the typical combination of brick exterior and block interior used on schools and churches.
Reduced air infiltration. This also adds significantly to the comfort and health of ICF walls. Imagine for a moment that you have a building with walls and ceilings that have a whole wall r-value of 1000, but the door is wide open. All that insulation doesn't do you a whole lot of good does itω ICF's keep the conditioned air where it belongs!
A newly built stud wall has an air change rate of .35 air changes per hour. The best test on a stud wall I have ever heard of is .15 ach; from a builder who caulks all joints meticulously.
ICF's routinely achieve .10 ach, and have tested as low as .01 ach! This is attained without the meticulous attention to details required by a framed wall, like caulking pates to each other, calking studs and headers to each other, caulking the sheathing to the studs, watching the insulation installation, and exterior air/moisture barrier. There are simply fewer parts and steps required to build the wall; therefore fewer details to pay attention to.
This translates into your HVAC system having to do 1/3 to 1/10 of the work to condition the air blowing into your home through air leakage!
Thermal mass effect. Perhaps this is the factor most people, including experienced builders and energy raters, fail to take into account. Most likely because it is the most difficult factor to quantify.
Concrete absorbs significant amounts of energy. While concrete is a conductor, it does not conduct quickly.
This energy is stored and released as the outside temperature changes.
Since the concrete core of the ICF wall stores so much energy, it takes a long time for outside temperature swings to "get through" the wall. Testing done on one of our homes by the Grand Valley State University School of Engineering indicates that the core temerature takes days to make a significant change. It also showed that from a hot summer day to a cold winter day, the difference in core temperature was not more than 22 degrees.
This means that the only work the inside width of the insulation has to do is to insulate a difference of 22 degrees! You have a continuous r-11 or higher barrier that only has to insulate 22 degrees!
This "thermal mass effect" allows us to downsize the HVAC systems because they don't need to be sized for the peak temperatures of the day. Furnace does not need to be large enough to handle when the temperature drops to it's low point a few hours before morning, and the AC system does not need to be large enough to cool when the sun is at it's hottest. So the HVAC is smaller, and therefore uses less energy.
It is true that the thermal mass effect is greater when the insulation is all on the outside, and the mass is all on the conditioned side. This situation would contribute even more to efficiency, but hey, ICF's aren't perfect!
Taken together, these three items have a synergy that no one item alone could effect. It is simply not possible to duplicate the performance of an ICF with a SIP or with stick framing; no matter how much you caulk the seams or sheath the exterior in insulation.
To prove this point, look at the following gas bill summary for 2007 in a home we did in Walker, Michigan in conjunction with Venture Design and Construction. It should be noted that this home has 2 rooms over garages that are stick framed and spray foamed; and thus not ICF. Results would be even more impressive had these areas been ICF!
Jan. 2007 $110.35
Feb 2007 $153.91
March $148.42
April $92.04
May $68.50
June $38.67
July $38.67
Aug. $36.23
Sept. $34.21
Oct. $31.94
Nov. $43.49
Dec. $121.46
Now, before you tell me that your bills are lower; keep in mind that this bill includes gas for water heating, cooking, and clothes drying. Oh, and did I mention that there is around 4,100 sq.ft. that is heated! Part of that is the basement that is kept closer to 65 degrees.
We see that in the summer months, the bill was still between $35 and $40 dollars. This is the amount of gas not used to heat the home. If we average that number, we come up with and average of $35.94/month. Although this number is most likely higher in the winter months, we will use it as it is.
Thus the highest heating bill is for the month of Feb. in the amount of $117.97. The annual heating cost is now $486.61, or $40.55 per month. How is that to heat a 4,100 sq.ft. home that isn't full ICF's?!
Click here for a spreadsheet of gas bills from the home we did with GVSU school of engineering. This home has 8 adults living in it, taking hot showers, dryng clothes, and constantly opening and closing the doors. One of them insists on keeping a bedroom window open.
Case studies like this do abound, but having one from your own climate and a builder you can hire yourself is most fitting. I should include the fact that your choice in windows, home orientation, ceiling insulation, and other factors will contribute to your overall energy efficiency. ICF's are not the end all of energy efficiency, but once you have ICF's you have in one step done everything that can be done for your walls, and now you can focus on the other items.
ICF's are the most energy efficient wall system available at any cost, and it's results cannot be duplicated by any other system. Call us today for a free quote!
