Why does efficiency matter?
Americans will have varying priorities, but there are some common factors.
Americans care about their health, many spending thousands per year on supplements, health clubs, and the like. Given the amount of time we spend inside, our homes can have a significant impact on our health. Mold, viruses, bacteria, Volatile Organic Compounds (VOC’s), temperature swings, dust, pollen, CO2 level, Oxygen level, and so much more are markedly improved in our healthy, comfortable, and efficient homes.
The primary reason so many people are giving Insulated Concrete Form (ICF) construction a close look is the energy savings our homes are renowned for. While most building science experts are pretty reserved, those who live in ICF homes are true believers and spread the word.
But what makes our homes so efficient? Is it just the Insulated Concrete Form walls? And why do ICF’s perform so well?
The short answer is that ICF walls are an important piece of the puzzle. Our standard ICF wall has an r-value of 23. Very easily you can upgrade to r-35 and beyond, but you may not want to do that. R-value alone is not the entire picture. Our homes perform well because EVERY piece of the home has been tuned to work as a system to deliver exceptional energy performance. In other words, it isn’t ICF construction alone. ICF’s do, however, have a very significant role to play.
ICF efficiency is due to these three properties: better insulation, Continuous insulation, and Thermal Mass. Let’s briefly look at each in turn:
Better insulation
While every type of insulation has its purpose, some insulations are better for your walls. Loose fill insulations are particularly prone to a problem known as “convective looping”.
Here’s what I mean: Let’s imagine we have an insulated wall cavity that is perfectly air-sealed (and air leaks only exacerbate the problem). Cold air on one side and hot air on the other introduces a convective force: one side heats the air within the insulation while the other side cools it. Air moves within the insulation, from one side to the other; and this convective current only increases in speed as the temperature outside drops. Thus, the colder it gets, the more rapidly your walls lose heat. The thermal performance declines just when you need it the most!
Solid insulations, such as Expanded PolyStyrene (EPS) do not have this problem, as they prohibit the movement of air. But not all solid insulations are equal either. There are some whose performance degrades quite dramatically as the mercury drops. So, to recap, solid insulation is better, except when it's not. Got that? If you’re taking notes, just specify EPS insulation, and all will be well.
Continuous insulation
Continuous insulation refers to the way the concrete core of the wall is sandwiched between uninterrupted layers of EPS insulation. It isn’t difficult to understand why uninterrupted insulation is far superior to conventionally framing and insulating a wall. Just try downhill skiing in West Michigan with an exposed midriff!
The picture above shows just how much of a wall cannot be insulated when stick framing; in most cases, the framing displaces over 20% of the insulation. This is making Swiss cheese out of our insulation “coat”! Thus, the actual thermal performance of a stick-framed wall is pretty dismal when compared to the rating of the insulation. This may be small potatoes in Honolulu, but in Grand Rapids we need to pay attention to such matters. Shocking, I know, misleading product data!
Thermal Mass
This one is a bit harder to quantify. We’ll expound it further in a future blog post, but for now, think of the concrete mass in the center of that insulation as a giant battery that takes a long time to charge and discharge. The difference is that this battery stores heat, not electricity. This long time period evens out the highs and lows of the day and even week. The thermal mass of an insulated concrete home means you will never be too cold one night and too hot the next day.
Taken together, these three factors contribute to a standard r-23 ICF wall outperforming any other r-23 wall. And that is without mentioning the airtight performance of an ICF wall. Click here to learn why air-sealing matters, perhaps even MORE than r-value!
