I’d like opinions about the above and perhaps a few reasons why you think or think not so. Thanks much!
Don
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"Green building" is one of the most subjective terms we've got. But I'll take a shot at it anyhow.
A material choice alone doesn't make a building green. A strawbale home is not necessarily "green" as far as I'm concerned.
Green building takes into account the energy use and other environmental impact of a house over its lifespan. Buildings should last a long time, use relatively little energy to heat, cool, and maintain, and be comfortable and healthy for the occupant.
ICFs can be a very good material for "green building", because a home built with them can last a very long time, and be economical to heat and cool while being comfortable. The durability and efficiency of the material offsets the high embodied energy of the concrete, and the use of petroleum in the foam.
It's not too hard to build a "non-green" home with ICFs though, it just needs to be uncomfortable, inefficient, too big for the occupants, so poorly designed that it's torn down in 10-12 years, etc.
Basically, I think that anyone who calls themself a green builder just because they use ICFs is trying to cash in.
zak
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin
"so it goes"
Well said, Zak.
How serious is the insect boring problem? Here in MN I don't think it would be the issue it would be elsewhere but it still is my one reservation about the ICF systems I've looked at.
I'm not particularly green, but I used ICFs because I want to save money on heating and cooling.
I only built the house once, but heat or cool it every year.
I would think folks interested in green values would see this logic as valid.
Treat every person you meet like you will know them the rest of your life - you just might!
Brian
I also believe that an ICF house would survive weather better than a wood house will. I mean extreme weather.. It would depend on how the roof was attached, but if you assume it is attached with Simpson clips I believe the roof could remain in place with a much higher wind speed than one where nails are used to hold the rafters on..
I also believe that durability is much greater with a ICF house than a wood house.. All of the ancient buildings that survive thru centuries are made of stone and an ICF is simply a way to get a whole bunch of small stones organized..
With durability comes green. in that something is green if it survives longer than the energy used to make it takes to be replaced..
jc21
If the ICF is made with borate in then a few bites and the bug crawls off to die.. It would take a pretty amazing group of bugs to do any serious damage..
My ICF shows zero, no sign of insects. Even when I had to dig around the footings this summer to install a new phone line I saw no evidence of anything crawling on or near the ICF's My ICF is nearly six years old and you'd think that if it was going to be a problem it would start to show signs by now..
PS I'm in Minnesota
That's great, assuming the insects actually eat the foam. Carpenter ants, as an example, bite away the wood to create nests and tunnels, but don't ingest it. I've seen them living in foamboard (they essentially hollowed out about 4 sheets in my old basement... the mass of "sawdust" on the floor led me to discover them) and in CCA lumber.
If all they're doing is using their pincers to relocate the material, I doubt if the borate will harm them.
Tomrocks21212
I believe that what happens is bugs throats close up with exposure to borate.. that's what causes them to die.. There are about a zillion carpenter ants in my neighborhood and yet they are extremely rare in the house. Since I have so much wood in my house it's a big deal with me..
Luckily I have a friend who teaches entomology at the U of M who like to hang around and play timberframer with me.. he's looked carefully at my place and sees no signs of insects attacking the place. If he ever did there are plenty of treatments to eradicate them..
Right now there are about a bizillion lady bugs and boxelder bugs trying to find their way into a warm spot for winter, but I found that simple vacumm will remove them all once it gets really cold..
Green Building is just a marketing scheme.
Just think of 5 reasons that ICF's are green and tout them like they are going to solve the worlds problems.
Now your green.
As Zak says, the material itself is not what makes a building "green". The point with ICFs is that they supposedly save much more energy over the life of the building than it takes to create them and also more than many potential substitute materials.
The downside of ICFs include that that some of them contain flame retardants that are thought to be carcinogenic. Some also use may use blowing agents that have some negative impact on the ozone layers (not nearly as bad as what they used to use by a ratio of something like 20 to 1, but still a small impact - although many use blowing agent that only have a minor impact on global warning).
I like the wording some ICF manufacturers use when describing their polystyrene units: "has no nutrition value for insects". Of course they won't say that some insects and varmits love to burrow in the stuff.
Of course, not all ICFs are based on straight polystyrene. Rastra blocks and TechBlocks do use polystyrene but encapsulate it in cement which improves the fire resistance and insect resistance. Hebel and another block whose name escapes me use wood chips mixed in cement to produce an ICF.
The "R" values of the ICF wall is often given as including a factor for "thermal mass equivalent" (or some such term). Since I am not much of a believer in the usefulness of thermal mass when outside temperatures are low, I tend to discount some of the published R values. Tech Block now claims an R value of 47.5 for their 11" wide block. That might be true if the entire 11" was polystyrene, however, since the cores of the blocks are filled with concrete and rebar, and the block itself is a mix of cement and polystyrene, I am guessing the actual effective R value is closer to 13 than it is to 47.5.
The name you were trying to think of might be Durisol, the first ICF.
Most of the manufacturers seem to have toned down their wild claims of R value, but they all still note that there's more to heat retention in a house than R value.
You might be interested in the study in the following link. It was sent to me by "experienced" which was very big of him as he is not a fan of ICF.
The study is a computer modelled comparison of one house design built different ways in 25 cities in Canada and the US. It shows that, in terms of energy use for heating and cooling, ICF construction is superior to all others modelled in every climate they looked at.
(In my opinion, it is superior to wood construction in a lot of other ways as well.)
The ICF they chose to model is one like "Lite-Form" which had walls of 2" styrofoam SM and polyethylene webs. Nobody around here uses it anymore because it was a major PITA to keep straight and plumb. Everything I am aware of now has at least 2 1/2" walls. You would think there would be some additional evergy saving from that.
Mind you, it was paid for by the Portland Cement Association. On the other hand, it was done by a reputable engineering firm.
http://www.concretethinker.com/Content%5CUpload%5C296.pdf
Ron
Zak said it pretty well.
I have one disagreement with what is usually touted as an ICF bennefit: For thermal mass to function as an aid to interior heating, that mass cannot be insulated from the interior. I can't imagine how some of the claims can be justified, given that simple fact.
I also have one question about the foam: How long will it last?
I've seen foam in many states of partial decompostion. I know that uv exposure may be the primary problem with foam decompostion, but comparing it, as another post in this thread did, with masonry structures that have survived centuries is, IMO, laughable. True, the concrete may last a very long time, but what evidence is there that the foam will last?
I expect that in the decades (and centuries) to come, those studying building materials will have a lot better data upon which to judge our current methods. Then they'll know how the various foams, treated lumber, ICQ lumber combined with metal fasteners, etc. will hold up over time.
Even concrete, as now mostly used, has not been tested for a long period.
I'm not saying the results will be anything in particular (good or bad), just that the scientific method requires time and testing by many folks in many places before the true strengths and weaknesses of any specific material are known.
I also know that I saved substantial money by forming and pouring my own foundation, even when I include the 4" of closed cell foam I put on the outside of the concrete. I built the entire thing, foam, steel, and concrete included, for less than the quote I got for ICFs (and of course that quote didn't include labor, steel, concrete, pump truck, etc. which I needed either way.) I reused the 3/4" ply form material as roof sheeting.
I do like the quiet and solidity of an ICF building, but those are qualities of the concrete, not the ICFs.
+++++++++++++++++++++++++++++++++++++
"Doubt is not a pleasant condition, but certainty is absurd." Voltaire
All other factors being equal, ICF construction represents construction tightness (i.e. resistance to air infiltration heat loss) about the same as or somewhat better than a house built with spray foam or dense-packed cellulose.
Static R values of the walls are similar, and don't matter much when you run the calcs- the biggest losses remain infiltration and glazing in that order.
I don't buy the argument about the thermal mass benefit of ICF. It may provide a bit of day to day moderation in extreme temperature which keeps you from reaching for the thermostat to crank the heating on, which may save a few days or weeks of heating. Some benefit, but not much real benefit. If temperature moderation is your goal, search for "passive annual heat storage" on this site and find the REAL way to do this!
The embodied energy in the manufacture of the polystyrene foam isn't even worth considering in my view. It's trivial in relation to the embodied energy in making the concrete, much less to the energy it saves by acting as insulation. Amongst the more conventional insulating materials, dense-packed cellulose wins if you do care about the embodied energy of the insulation material itself.
Does any of this make ICFs "green construction"? Dunno. From what I've seen, "green" is marketing babble or religious talk more than it has anything to do with reality.
What ICFs DO offer is a reasonable means for a DIY to build their own basement walls. I couldn't have constructed single-use forms for my own basement for less than the ICF forms cost me, unless I accounted my own labour to construct forms at absolute zero AND I allowed salvage value for all the wood used to make them. In fact, I couldn't buy the materials to build single use garage grade beam forms for less than the ICFs I used for this purpose cost me- even accounting my labour at zero cost. With some basic hands-on training/help to get going and some help with the pour ($500 total) it was relatively simple to do the job. The labour required was light and not at all unpleasant. The result is excellent- the walls are very straight, interior finishing was a breeze, and there is no question that the construction is tight and built to last. My ICF foundation was, based on quotes in hand, the greatest budgetary savings on my DIY addition project relative to any alternatives I considered, including having someone lay block- a far inferior wall construction in my view, even if you forget about the insulation entirely. As much as I enjoy wood framing, f I had to do the project again, I would have poured the sucker from top to bottom!
Cave dwelling and living in igloos is green building.
Everything else compromises "green."