http://www.forms.org/images/cmsIT/f...ect(1).pdf

I'm adding this topic because it keeps coming up and taking other threads off course. 

Now that the best performing schools in the US are predominately mass wall systems (see ASHRAE K12 50% solution) - with the best performing school currently utilizing an ICF wall system and operating at 17 kBTU/sqft per year --   I believe this has been put to bed.   Thermal mass is real and the newest charts even show that mass wall (Heat Capacity > 7 BTU/sqft F ---  with R-value X beats a low mass wall with R-value somewhat more than X in all climate zones.  

ORNL states that mass walls performs slightly better with their mass to the inside whereas ICF has it's mass in the middle.   I am not entirely convinced this more immeditate or direct interaction of the mass with the interior might not be better sometimes or in some climates than in others.  Nevertheless, it very well may be true.  However, to equal a typical 6" ICF wall this equivalent wall system is going to have to have an R-20 - R22 exterior insulation with 6" of solid interior unobstructed concrete -- thus matching the R-value and heat capacity of a 6" ICF wall.    Thanks in advance for your thoughts.  Regards.

Posted By Lee Dodge on 22 Jan 2012 05:37 PM
The link that you provided to the ICF manufacturers association restated conclusions from the report by VanderWerf (reference 2) that was performed for the Portland Cement Association. In that report comparisons are made for energy use by ICF homes and wood frame homes in similar climates with similar floor areas, all of relatively new construction -- new whenever the undated report was published. There apparently was no effort to match wall insulation R-values! So a house with 2x4 walls with fiberglass that has an R-value of R-11 uses more heating and coolng energy than an ICF house with R-22 walls. Is this conclusion surprising or even interesting?

A more interesting comparison would be to use a fixed budget to spend on a house of the same floor area, and see if the money is better spent on ICF construction or wood frame with a very high R-value, which would be possible since there is a considerable price premium for ICF construction, much of that due to the requirement to use rigid foam rather than cellulose of fiberglass, which are much cheaper per unit R-value. Perhaps you could perform some calculations with BEOpt which has prices for different construction and report back to the group on equal cost houses.

After a brief glance, about the only thing that I saw of interest in the VanderWerf report was Figures 1 and 2 and the comments made relative to those figures. Those figures appear to undermine the thermal mass effect advantage for ICF.

Perhaps this paragraph: "There are theoretical reasons to expect that the fractional savings in energy might be different in different climates.  For example, the thermal mass effect should be more pronounced in moderate or warm climates because the outdoor temperature there more often fluctuates about the thermostat set point. Thus fractional heating savings might be greater."

Regarding BEOpt that might be a better task for you since most of my data is emperical.   Regarding cot of ICF:  It usually it costs about 5%-7% more (for the entire cost of the dwelling) for ICF over conventional -- e.g. a 200K conventional house will run 210K-214K after reducing reducing AC tonnage and pulling out the cost of labor and materials for the external envelope and applying them toward the ICF.  Naturally, this percentage value goes up with smaller houses and down with very high end houses with finer finish out.   In Texas, ICF homes usually go from $10 to $12 per gross square foot of wall turnkey.  Complex structures with lots of radius walls etc. or 350 mph rated structures etc.  will be higher.  By comparison, here we usually find conventional construction is about $4-$5 per square foot of external wall.  New code -- eg. IECC 2009 and the forthcomming IECC 2012 are going to generally make conventional construction more expensive and will generally not impact ICF much at all.   

As you know, the reasons to go ICF typically vary from person to person.   When comparing ICF to conventional, you'll need to upgrade a bit on what considered conventional here to reach the thermal performance of ICF.  I would say there are just as many folks that prefer the safety of a concrete home or the STC (sound transmission characteristics) of an ICF home -- perhaps they are building near a railroad or a highway.   Occasionally, and more recently, I might add, they are looking for a three or four hour fire rating because their previous home burned down.  

Based on the many homes I've been involved with I believe in general it's as good as construction gets for the money.  As soon as you start trying to get similar strength or fire resistance or STC "and" energy efficiency out of conventional construction I belive you are going to pay more for it than for ICF.   Regards.

Posted By lzerarc on 23 Jan 2012 10:50 AM
TX-
I fail to see what that pdf proves. It claims what we already know. We know mass in buildings, if used correctly, can affect the performance positively. What we do not know, and have yet to see any proof (besides the "old" reports that actually disproves it...) that the sandwich mass in ICF has the mass effect ICFers (you) claim, especially in heating dominate areas which is a great deal of the US. Further more, the ICF case study in the school (which you have to agree the requirements and performance of a school vary greatly compared to homes) does have a high performance level. However how are you sure that the pure insulated levels of the ICF are not playing into it compared to externally insulated mass walls? Code in our area only requires an r13 for CI on mass walls. So that is what we put. Of course if we use an r24 ICF wall it will perform better then an r15 mass wall. Same with frame walls. I do not think anyone on here will disagree with an ICF beating a frame wall with batt or blown insulation. CI and air tightness are playing into it big time, however the thermal mass?
What I want to see is a compared wall assembly built to similar thermal breaks, insulation levels and air tightness of a typical higher cost ICF wall. Better yet I would want to see a double stud r40 wall compared to a typical r24 ICF wall (who many ICFers claim pushing r40s due to the "mass effect"). I already know the results cause we have ones around my area to compare.

Posted By lzerarc on 23 Jan 2012 10:50 AM
TX- 
However how are you sure that the pure insulated levels of the ICF are not playing into it compared to externally insulated mass walls?

Posted By lzerarc on 23 Jan 2012 12:44 PM
We could debate the wall make up of the double stud, compare framing factors, prove its not really r40, blah blah blah. On paper, we can look at numbers all we want to. It doesn't have to be double stud. It can be any super insulated shell vs ICF. SIPs, PERSIST, etc. What most of us are suggesting is numbers are not doing the talking any longer. There needs to be more apples to apples studies comparing performances. ICF companies compare their shell to 2x4 or 2x6 with batts. There is not a single person on this forum that would disagree with ICF being much higher performance compared to those. My point was how does it compare to super insulated homes that cost less? Why are they not comparing ICF to these? Or in some cases even above code min. structures. In my area a 2x6 with batts doesn't meet IECC anymore without CI.

IZ - but everyone is comparing the extra cost of ICF to conventional homes NOT to other SI home i.e. 10 to 15% more. Bob

Around me there is a new home that was recently finished using the double stud detail we did. So far the performance can not be touched by other ICF homes we are comparing it too, most of which do have spray foam ceilings. It is a larger home with close to half the heating cost in the last month of a smaller ICF home we are comparing it too. Sure, there are various variables, but the fact is SI wood structures can and do work, very well. If not why would PH be using these construction methods and rarely full shell ICF? (most do us ICF on the basement).

IZ - I was involved with a number of the early R2000 home in the 80's in the Calgary Alberta area. Not one of these comes anywhere near the efficiency today that they did when they were built. Why? Primarily because they were built from wood. No matter how you seal it, wood will respond to moisture and temperature. As it changes shape and moves it will eventually degrade the best airseal. Once the airseal is gone, infiltration takes over as the limiting state and all the R becomes less meaningful. Bob

Not knocking ICF, it is a very good, strong structure with many great attributes about it that has me thinking long and hard about it as a good option. However it gets roped into the high efficient category far to often. For the cost, and the goal of high efficiency, your dollar is spent better elsewhere IMO. Wind, storm, fire, sound? ICF all the way if those are your goals. To be honest if budget was 0 concern, I would do a full shell ICF and add another 2-4" of EPS on the exterior.

Posted By Chris Johnson on 23 Jan 2012 09:29 PM
The R-50 as you know is a false number.

The ICF industry needs to get together and build TWO identically sized homes next to each other. Both with identical HVAC equipment and identical temperature settings. The one home utilizing ICF and the other 2x6 wood frame with foam or cellulose insulation and then 2" of EPS on the exterior. Put sensors and monitors throughout the home and record the data for an entire year. Then publish the results. This would settle it once and for all. Well, at least for 90% of the people it would.

Didn't they already do this at Oakridge National Labs?

Posted By toddm on 24 Jan 2012 11:52 AM
It isn't ASHRAE describing ICF's mass effect as cavelike. It's you, TexasICF. So let's see some documentation that the FTC would bless. At this point, I'll accept ANY form manufacturer's effective R value report.

No you don't have justify yourself to me. Even so, you might pause to consider whether readers of this thread have recognized by now, to borrow a Sherlock Holmes theme, why the dog hasn't barked.

Posted By toddm on 24 Jan 2012 09:15 AM
It has been done, in fact, Lbear, and several times. Trouble is, the ICF crowd doesn't like the results. The whole mass-effect-claim issue was resolved many years ago for every wall system except ICF. Again, ICF manufacturers could have defensible effective R value numbers in a mater of months. Same problem: They aren't that impressive.

Posted By toddm on 25 Jan 2012 08:43 AM
Lbear, I linked to the ornl study above. Briefly,ornl and icfa built icf and stickbuilt houses in knoxville in 2000 and measured their performance over 11 months. Occupied, the icf house used about 9 percent less energy. Unoccupied, the difference was 7 percent, while DOE2 said 6.8 percent. Climate has a bearing on mass effect, so your results will vary.

Posted By toddm on 25 Jan 2012 08:43 AM
Lbear, I linked to the ornl study above. Briefly,ornl and icfa built icf and stickbuilt houses in knoxville in 2000 and measured their performance over 11 months. Occupied, the icf house used about 9 percent less energy. Unoccupied, the difference was 7 percent, while DOE2 said 6.8 percent. Climate has a bearing on mass effect, so your results will vary.

Posted By Lbear on 25 Jan 2012 04:35 PM
Would the mass effect play a bigger role in a climate that has 30+ degree temperature swings within a 24hour period? If so, what would that effect be?

Posted By dmaceld on 25 Jan 2012 06:37 PM


You can probably intuitively see that 10 ft of insulation and 10 ft of rock both moderate heat movement, one by resistance and the other by absorption. Back to your original question about a 30° temp swing. What matters more than the extent of the swing is the average temp of the swing and the total amount of the mass and the total amount of insulation.

Those who argue that mass has less impact in the heating dominated climates compared to the cooling dominated climates are partially correct, IMO. That's because in the cooling dominated climates the temperature swing average is fewer degrees above normal room temp than the average temperature swing in the heating dominated climates is below normal room temp. [I could be wrong as I haven't looked at the temps in detail.] They tend, however, to ignore the moderating effect of the concrete mass which leads to a more uniform heat movement and therefore greater comfort.

Posted By Dana1 on 25 Jan 2012 03:49 PM
The DOE2 modeling for the twin houses was in fact validated by the actual measured performance of those houses, with all of the infiltration factors and other known differences duly noted (and modeled).

The measured energy use of the ICF house fell within 1% of what was predicted by modeling. (DOE2 must be pretty lousy at modeling ICF and thermal mass issues to have missed by that much, eh? :-) ) See table 3, p7:

http://www.ornl.gov/~webworks/cppr/y2002/pres/114086.pdf

The DOE2 model proved less accurate on the stick-built, which isn't a surprise given that it was batt-insulated not blown (or sprayed), but was still hit within 5% on the cooling energy, and within 0.5% on heating energy. Yup, as sucky model indeed, not to be trusted...

The ICF house also had a raw whole-wall-R of R15, compared to the stick built (straw man?) 2x4 house's ~R10.6. (This was presumably true for all of the other-climate modeled results.) What, and R15 wall outperforms an R11 wall? Go figure!?!

Yes, the mass was a factor (and duly modeled), but so was the additional R (also duly modeled), and in none of the simulations did the modeled difference end up in double digits. (But it might have had more variation in real houses, if the builders were sloppy on air sealing, and the insulation installations 3rd rate as happens.)

Yes,the mass had an effect beyond the ~40% higher wall-R (which is real performance upgrade even on a low-mass wall) but the modeled and actual performance delta between the real physical houses was still in single digit percentages. Call the whole experiment crap if you like, but it's way more representative than marketing BS. It wasn't designed to do-in or underplay the value of building with ICF (quite the contrary.)

Bottom line, there's more to building an efficient house than a high wall-R or thermal mass.

Posted By lzerarc on 25 Jan 2012 07:13 PM
dm- interesting example. However after all of that, something that stands out to me is....a 2000sqft house and a 36k btu HP?!! Shouldnt the heat requirements be much lower for ICF?....(at least that is what we are being fed)

Posted By dmaceld on 25 Jan 2012 11:38 PM

Would I build another ICF house? At this point I cannot honestly answer that. I am somewhat embittered at what it cost me to build this house compared to what it's value was appraised for when I converted the construction loan to a mortgage, i.e., 30% less. I started building near the peak of construction activities in Idaho and nationwide so I got no super bargains on material or labor. I'm sure I spent more for this ICF house than a frame one would have cost, but I don't have a handle on how much of that extra cost was the ICF system vs. the extra time, and in some cases money, I spent to build a damn good solid high quality house without useless frills. I got the mortgage after the first wave of the housing recession, so I got whacked twice. It hurt bad. So when it comes to asking if I would do it again I'm not in the position to be real objective. I guess I haven't completely gotten over my anger at the way things turned out.

Posted By dmaceld on 26 Jan 2012 12:03 AM
LBear, if you are comfortable running scientific computer programs go to http://www.energy-design-tools.aud.ucla.edu/heed/ and check out the HEED program. It's free and I think pretty good. It'll take a little time but you could input all kinds of house envelope options and get descriptive outputs showing how those different envelopes affect energy consumption, both on a daily basis as well as annual basis. It'll use the temperature data for any area you want to consider.

FBBP and others,

You guys have made some very interesting observations about this report.

Here are a couple of thoughts.

First to be fair, I'm not a fan because the results don't match what I see in my house and what my customers are seeing -- at least here in Texas.  I'm sure the report was compiled with all the right intentions.   Here's a couple thoughts as to why results might be somewhat different.

-- The identical houses were not really identical:

"About half of the ICF crawlspace floor was not covered by plastic in order to encourage drying of the water that leaked into the ICF crawlspace before landscaping was complete. This also justified leaving the ICF crawlspace vented during the whole experiment, contrary to original plans."  Really?

I had missed this entirely until FBBP pointed it out. 

-- I don't know of any R-15 ICF on the market today.  What ICF did they use?

-- What concrete core did they use -- and thus what heat capacity did they model?  Mass walls typical HC > 7 BTU/sqft F  and Typical ICF 6" core is about 13.

-- Why did they leave the attic vented?   I discourage that here because -- well, it just doesn't work.   In fact, if a customer does not want to use a closed attic I suggest (reluctantly) that ICF may not be for them.   That's letting the enemy in (heat) and fighting at close quarters.

Furthermore, 1000 square feet per ton is very common here (for ICF) and I have yet to under ton a house (that is to see an house without enough tonnage).   The report even states that the units were short cycling which is the kiss of death for efficiency.   I believe someone noted that air infiltration was too high for a typical ICF house.   Eliminate the air infiltration with the wrong tonnage and the units will short cycle even more.    

dmaceld -- I wasn't sure if your post was referring to your house and/or the report but I dont' think Daikin is not a good example for target tonnage because (I'm told) it is a very intellegent unit and can be overtonned without damage (e.g. as I understand it it is smart enough to ramp or stage down somehow and not short cycle).  Is that correct?    Regards.

Posted By TexasICF on 26 Jan 2012 07:35 AM
 

-- I don't know of any R-15 ICF on the market today.  What ICF did they use?

-- What concrete core did they use -- and thus what heat capacity did they model?  Mass walls typical HC > 7 BTU/sqft F  and Typical ICF 6" core is about 13.

--

Posted By toddm on 25 Jan 2012 12:49 PM
Then the Insulating Concrete Forms Association employees and designates who did this study with ORNL should give their salaries back, eh?

Posted By BrucePolycrete on 26 Jan 2012 11:26 AM
If anyone's interested, Polycrete Big Block 1200 has 1-3/4" of EPS per side and carries and R value of 16. It's still very strong, though because it also has the steel wire mesh in the panels just like the 2-1/2" EPS product.

Posted By TexasICF on 26 Jan 2012 07:35 AM

Furthermore, 1000 square feet per ton is very common here (for ICF) and I have yet to under ton a house (that is to see an house without enough tonnage).   The report even states that the units were short cycling which is the kiss of death for efficiency.   I believe someone noted that air infiltration was too high for a typical ICF house.   Eliminate the air infiltration with the wrong tonnage and the units will short cycle even more.    

Posted By Lbear on 26 Jan 2012 04:00 PM
Not to get off topic but regarding short cycling. All the homes I have been that have been "HVAC engineered", all had units would short cycle.

Posted By Lbear on 26 Jan 2012 02:33 AM
Nobody can predict the market and timing is a hit and miss thing. I know it's hard but beating yourself up over it will end up eating you up. The RE market tanked and a lot of people lost a lot of money. Between 2003-2007, the RE market was peaking and prices were high. Here in AZ, the housing prices have dropped to 2001 levels.

You are lucky that you are in Idaho, here in AZ the market is one of the worst RE markets in the entire nation. One can buy a 4 year old home, fully furnished, for $50 a sq.ft. That same home sold for $130 sqft in 2006.

Posted By BrucePolycrete on 26 Jan 2012 11:26 AM
If anyone's interested, Polycrete Big Block 1200 has 1-3/4" of EPS per side and carries and R value of 16. It's still very strong, though because it also has the steel wire mesh in the panels just like the 2-1/2" EPS product.

Posted By dmaceld on 26 Jan 2012 06:56 PM

You gotta wonder what kind of "engineering" was done. So many tons per 1000 sq ft + add one for extra margin? Even if it was half-assed engineering the HVAC units shouldn't short cycle that often.

That's what I like about my Daikin heat pump. It has a variable speed compressor and sophisticated control board. It almost always only cycles once per day, winter and summer. In the winter it kicks on late in the evening and off late the next morning. Summer a/c cycle pretty much the same but  several hours earlier. There have been times in the summer I go outside and the condenser fan is barely turning with very little heat coming off, and the compressor is running so slow you barely hear a hum. It's almost uncanny how the compressor runs just fast enough to move only the amount of heat necessary to keep the house temp constant and within about a half degree of set point.

With a good control system and a decent size reserve tank you can accomplish this same level of performance with a ground source heat pump and hydronic system.

Posted By TexasICF on 26 Jan 2012 04:20 PM
Sounds like a fix but perhaps not really. In an ICF house that is very tight you need a small enough unit so that it will run long enough to pull out humidity. I know there are plenty of A/C guys out there that know what they are doing -- but (ICF or not) if your A/C is short cycling you are getting HVAC "guesswork". Regards.

Posted By BrucePolycrete on 26 Jan 2012 09:21 PM
Just once I'd like to see someone post something positive on one of these forums. What a bunch of whining, complaining, miserable negative, disputative, annoying, collection of individuals. Maybe you should all have a Jim Jones experience and settle it once and for all. Kool-Aide anyone? I'll supply the dixie cups.

Posted By Lbear on 26 Jan 2012 07:43 PM

With the compressor pump running for all those hours, wouldn't that drive your electric bill through the roof?

Posted By toddm on 27 Jan 2012 11:21 AM
To clarify, less foam equals a higher mass effect multiplier in Phoenix.

Posted By toddm on 27 Jan 2012 04:17 PM
Your area would be right up there, but I'd be guessing. If you have a site that would accommodate passive solar you'd be golden (unobstructed southerly view with no one looking back.)

Dmaceld gave you the link to UCLA's design tools. Climate Consultant has a chart that tells you how many hours a year high mass or passive solar/high mass would keep you comfortable without hvac. HEED allows you to rough out your design with windows, doors and house orientation in place and model its performance. It pretty easy to use, has ICF options if I remember right, and plugs you right into DOE2 without "interpretation" by TexasICF or me.

Bruce Polycrete, Climate Consultant liked high R ICF for Pa a whole lot better than my plan but who is rational about houses, eh? Given the window walls in my Frank Lloyd Wright tribute. passive solar and interior mass make sense even all that glass does not.

Posted By Lbear on 27 Jan 2012 07:19 PM

The home will be positioned to face due south, with the majority of the windows on the south side of the home. I hope to utilize as much passive solar gain as possible in this home. During winter solstice the sun would be positioned just above the mountain range from east to west.

So I hope with the ICF, good windows, and passive solar design to keep my heating costs low.

Posted By dmaceld on 27 Jan 2012 09:59 PM

Here's a link to a neat calculator to plot sun position throughout the year http://solardat.uoregon.edu/SunChartProgram.html.

I used it when I was designing my house to calculate how long of an overhang I needed to block direct sun in the summer and maximise sun entry during the winter through the SW facing windows in my house. It worked out. Right now we have fairly direct sunlight coming in during the afternoon. In the middle of the summer there is no direct sun coming in. The info from the plot not only played into the overhang design but also helped me determine window height above the floor and the height of the windows. I'm actually rather proud and quite pleased with what I was able to accomplish.

Posted By toddm on 29 Jan 2012 08:23 AM
I haven't updated this recently: http://www.flickr.com/photos/58061641@N06/

With passive solar, you'd definitely want mass exposed to the interior. An ICF wall would be little use in a late-aft overheating episode because the interior foam would delay its buffering effect.

Generally, you don't want windows facing west because there is no way to shade them. In my case, trees do the job quite well.

Todd, 

Very nice home!   

I do like the DBMS ORNL stuff -- but it is the lack of definition around effective R-value or R-value equivalent that's made it appear that ICF vendors are misleading potential buyers as they market R-value.   Consider from the report:
  

R-value Equivalent for Massive Systems is obtained by comparison of the thermal performance of the massive wall and light-weight wood-frame walls, and they should be understood only as the R-value needed by a house with wood-frame walls to obtain the same space heating and cooling loads as an identical house containing massive walls. There is not a physical meaning of the term “R-value Equivalent for Massive Systems.”

That is a little difficult to follow but let's go with it.   ORNL shows that in Phoenix the Dynamic Benefit of Massive Systems (DBMS) is significantly better for an R-17 wall with the mass on the inside than for an R-17 ICF wall with mass in the middle (between the foam).   And they show:   DBMS = R-value equivalent/Actual R.   Therefore, based on the chart we have:

R-value equivalent for R-17 ICF wall is about 25.

R-value equivalent for R-17 Internal mass wall is about 40.

To your point about DBMS in Phoenix it doesn't get any better anywhere else for DBMS. 
 

But I don't think it's all that clear --- for example --- how does AAC fit into that?   From ORNL:

Masonry or concrete walls having a mass greater than or equal to 30 lb./ft ² (146 kg/m²) and solid wood walls having a mass greater than or equal to 20 lb./ft ²(98 kg/m²) are defined by the Model Energy Code [1] as massive walls. They have heat capacities equal to or exceeding 6 Btu/ft^{2   0}F [266 J/(m²k)]. The same classification is used in this work.

Solid wood walls weighing 20 lb/sqft have specific heats great enough to give them an exceptable heat capacity to classify them as "mass".  By the same token, some AAC is just under this baseline of 6 Btu/ft² F heat capacity and some thicker AAC is over it a bit.  Basically, AAC is mass system with a low heat capacity. Incidentally, ASHRAE defines a wall to be "mass" if it's heat capacity exceeds 7 Btu/ft² F.  This difference would exclude some walls from being classified as mass. 

How does ICF fit?  Your typical 6" core ICF wall has a heat capacity of around 13 Btu/ft² F. Thus ICF is a very high in heat capacity or about twice the ORNL baseline value.   What impact does this have on the report results.  I don't know but more heat capacity is good for DBMS.   ((Actually, I don't know this for sure as it applies to laboratory DBMS but I do know that if heat capacity is extremely high then it will take a long time for a building to "know" that it got cold outside and in fact despite diurnal swing it will also take a long time for the building to "know" that it "got colder" outside. ))  

What about R-value?

AAC actual R-value is about 8-10 (from what I gathered in search) and ICFs actual R-value is about 22.

If we look at Phoenix and utilize the DBMS for R-10 you still have an a strong effective R-value of about 25 which is actually still quite impressive.

So how does this translate back to the effective R-value chart for R-17 mass walls?   This value would be off the chart but based on the y=mx+b line they provided it's about 30 (it's off the chart as are almost all ICF brands on the market today). 
 
http://www.ornl.gov/sci/roofs+walls...html#whole 

I dug around quite a bit and found some other ORNL reports that did not attempt the dynamic part and seemed to say the opposite.

Since they have used least squares or similar to derive a straight line I don't think this is out of line.

I don't know for sure about this one way or the other but using this chart for AAC and ICF comparison is a little like using a screwdriver as a hammer.   It works but only to a point.  Regards. 

Posted By toddm on 06 Feb 2012 07:20 PM
No need to guess about AAC, Texasicf. AAC manufacturers built a representative wall in an ORNL hotbox, plugged the data into Doe2 and published effective R value numbers that the FTC accepts as legitimate claims.. Feel free to google. If memory serves, Phoenix was an effective R24. I used Washington DC to plug an effective R17 into RESCHECK and get my building permit. (Today, you'd need 10inch AAC walls to meet code in pa.)

No point in "translating" thermal mass either. If nudura, your brand, were to make effective R value claims the company must jump through the FTC hoops first. It doesn't and it hasn't, one guesses, because as ray Gladstone wrote earlier in this thread, why hand ammunition to your rivals by affirming that interior foam limit ICF's ability to buffer temp swings over 24hour periods?

Good news. TexasIcf. We are not as dumb as you think.

Posted By toddm on 08 Feb 2012 08:46 AM
An ad you didn't see during the super bowl: ford expedition! 50mpg!* (downhill, in neutral) So,FBBP, what's your view of the EPA?

Posted By Dana1 on 08 Feb 2012 11:12 AM
I'm glad that FBBP feels comfortable enough to speak for "most people" regarding hot box testing, but I'm having a hard time figuring out who these "most people" are, exactly.

The ORNL's large scale climate simulator guarded hot box approach does a pretty good job at determining how different assemblies behave in different climates, far better than ASTM C 518 applied to dumbest of 2D models. http://www.ornl.gov/sci/roofs+walls/tour/LSCS.html

Posted By Dana1 on 08 Feb 2012 02:45 PM
This is a FAR better (and more complicated & expensive) test than plunking the material in an ASTM C518 plate.

Posted By jmagill on 08 Feb 2012 05:33 PM
I don't think we have all the facts we need to properly discuss that scenario. In my neck of the woods. -26 means clear skies and lots of solar gain on our interior mass. Is that factored in?

Posted By FBBP on 08 Feb 2012 05:11 PMSo in my house when we had a week of minus 32ºc (also our design temp) nights with day time recover to only minus 26º, the mass effect of concrete should have abated. After the first two or three days, the R22 to 24 of the foam should have been the governing factor with regards to heat loss. Since the heating is designed "as if" the walls are R50, I should have been freezing by day three, should I not?

Posted By toddm on 09 Feb 2012 07:12 PM
My apologies, FBBP. I assumed you were deliberately misleading people until I reread the post you referenced above. What your hvac guy meant by R50 could be literally anything according to the fellow who wrote Manual J, and argues here that rampant oversizing isn't HIS fault: http://www.greenbuildingtalk.com/buildcentral/sip/article_hvac_sizing.aspx

If he meant actual performance of R50, he was wrong. Most likely he was adjusting your walls for thermal lag. Thermal lag is the considerable time it takes for heat to penetrate a mass wall, long enough for conditions to change on the other side. You'd get some buffering even in the dead of winter. Instead of a low of 0 and a high of 30, for example, the delay built into ICF might result in temps10 to 15 degrees higher. You can downsize hvac with ICF, and R50 was probably your mechanic's way of getting it done.

Your R value remains R22. While your walls don't cool as much as the identical low-mass house next door, they don't warm as much either. Average is average, and at no point is ICF manufacturing BTUs. But make the average daily temperature 70 and it is a different ballgame. A range of 67-73 is much kinder on the wallet than 55-85 -- as long as the mass is exposed to the inside and able to buffer temps on a 24-hour basis.

Researchers have done many actual tests on actual houses, including the side-by-side study in Knoxville in 2000 with ICF industry support. I know of no study that suggests that ORNL is wrong about ICF. (We know that fiberglass insulation isn't as good in the field as it is in testing because that research exists.) Anecdotal evidence won't cut it, even if it seems self evident to you.

Posted By FBBP on 08 Feb 2012 05:11 PM

Posted By Dana1 on 08 Feb 2012 02:45 PM
This is a FAR better (and more complicated & expensive) test than plunking the material in an ASTM C518 plate.

Fair enough. My apologies for suggesting otherwise

If the mass effect of ICF is just based on DBMS and hence the conclusions that ICF is best suited to high diurnal cycles, would it not be fair to suggest that after two or three days of fairly even day and night time temperatures, the effect of the ICF mass would be lost?

So in my house when we had a week of minus 32ºc (also our design temp) nights with day time recover to only minus 26º, the mass effect of concrete should have abated. After the first two or three days, the R22 to 24 of the foam should have been the governing factor with regards to heat loss. Since the heating is designed "as if" the walls are R50, I should have been freezing by day three, should I not?

Posted By toddm on 11 Feb 2012 08:36 AM

If you reject the knoxville ORNL/ICFA study as fatally flawed, seems to me you should be asking your trade group where they have been for the last 12 years. Spare us what the trades are trained to do. My dog is trained to find birds. That doesn't make her an ornithologist.

Posted By toddm on 11 Feb 2012 08:36 AM
Who says ICF isn't for cold climates? The upshot here, if any, is that ICF isn't the mass wall of choice for the southwest. ICF is the only mass house I'd build in Calgary, but I'd want for its insulation and tight construction rather than its concrete.
there is no mass effect at minus30C. The concrete right under the exterior foam will be a degree or two warmer, the concrete under the interior foam will be a degree or two cooler than 21C. From a btu's perspective it's all downhill from there.
Yes you know your home's energy consumption. The only way to know if it is better than the identical low mass house next door is to build that house and compare them.
If you reject the knoxville ORNL/ICFA study as fatally flawed, seems to me you should be asking your trade group where they have been for the last 12 years. Spare us what the trades are trained to do. My dog is trained to find birds. That doesn't make her an ornithologist.

Posted By toddm on 11 Feb 2012 08:36 AM
The upshot here, if any, is that ICF isn't the mass wall of choice for the southwest. 

Posted By toddm on 13 Feb 2012 10:48 AM
As another plus you get 90 degree corners and straight walls without waves, dents or bulges. Stucco is a step easier and cheaper... Plaster costs all in were less than drywall cost along for every sf, which is a requirement for ICF. Acoustic and fire ratings are better: four hours for AAC in the latter case...

Posted By toddm on 13 Feb 2012 01:33 PM
All I know is the icf contractor who built my foundation stem walls managed to make more mistakes and bigger mistakes in two courses (TWO courses) than my mason did in the rest of the house. The mason was appalled at how approximate the walls were, and this contractor came with the distributor's recommendation. Again, my advice is don't pick a wall technology that is rarely done in your part of the world.

My 8 inch walls are STC 47. They can be brought up to STC 68 at greater thicknesses and with an air gap. Interior walls panels are almost price competitive with stud walls and get you STC 40. With insulating and fire pluses as well, motel chains are liking AAC a lot.

Stucco over AAC doesn't require foam boards; the blocks are self insulating. By skipping the mesh, stucco is indeed one step simpler on AAC than ICF.

I have been careful not to generalize from my experience, which is not typical, or to impose my preferences on folks who are building different kinds of houses in different climates. You stop torturing the truth about ICF and you won't hear me from again.

Posted By toddm on 13 Feb 2012 07:18 PM

You confuse me Lbear. You have conducted the world's longest courtship of a wall system, which apparently is ongoing, except you say on a different thread today that you have hired an architect and are passing along detailed questions about ICF. So.... shill for the ICF carney barkers on this site?

 

Posted By FBBP on 13 Feb 2012 09:24 PM
My thoughts on mass in Phoenix.

If we say Phoenix temps are 90 during the day and 60 during the evening then the day heat will penetrate the exterior layer of foam, build up in the concrete till some of it penetrates the second layer of foam. With the insulation on both sides, the concrete can hold heat to its specific heat values. How long it takes for the heat to penetrate the two layers is a matter of R value.

If the mass and two layers of foam working as an assembly delay or slow the transfer of the 90º outside temps from reaching the inside for a period of say 6 hours than when the outside air begins to cool, the cost of mechanically cooling the interior will be reduced substantially because the ac unit is now shedding heat to the cooler night time temps rather than the daytime temps. The inside air can now also be cooled by natural ventilation. The heat still residing in the concrete mass will tend to move to the outside again because the outside air is now cooler than the inside air. This amount of heat does not need to be dealt with from the inside. In this case it is also possible that the heat trapped in the concrete mass between two layers of foam might migrate down to the cooler footing as this is the path of least resistance.

With all the insulation placed on the outside, the interior mass can only respond to the heat once it is already in the room. Also once the heat passes the outside insulation, it move readily into the interior space, no interior insulation means that the mass and the room temps will try to equalize. If this were not the case we would have to ascribe a much higher R value to concrete. It would therefore seem that heat gain from other than wall areas (windows etc.) will soak into the bare mass for a period of time in the morning but once the outside heat passes the outside insulation, this will stop and it will be the outside heat that is soaking the mass and than the mass will radiate it into the room. (heat transfer direction changes as the mass approached higher outside temps.) In the evening/nighttime, all the heat has to be dealt with as the heat will not go back through the foam to the cooler outside temps. ‘course you will still have the benefit of the cooler outside temps to work with.
So if most of the heat is coming from the walls ICF has the advantage. If most is coming through windows etc. external insulation has an advantage till the mass is effected by the outside temps, then because it becomes a radiator it becomes a disadvantage.
Feel free to disagree but please give logical explanations so that your reply builds up the knowledge base on this forum.

Posted By jmagill on 14 Feb 2012 06:35 AM

What you think and what the facts are are two different things. Having all the insulation on the outside doubles the time it will take for the heat to move to the interior wall.Having no insulation on the interior wall allows the concrete to react faster to the heat in the room, the whole point of having no insulation hindering the flow. Exactly what you want. Insulation on the outside to slow the heat coming in through the walls. Concrete on the inside so it can quickly react by absorbing the interior heat. The studies have already proven it. You have not. You have not given logical explanations or built up any knowledge base. It is all supposition.

jmagill - What you say is no different than what I said except that you seem to imply that NO heat will come through the wall. If you have sufficient insulation on the exterior you can slow it down. If you don't, than the mass becomes the enemy. Its just like a radiant floor at full temp.

Posted By jmagill on 14 Feb 2012 06:35 AM


What you think and what the facts are are two different things. Having all the insulation on the outside doubles the time it will take for the heat to move to the interior wall.Having no insulation on the interior wall allows the concrete to react faster to the heat in the room, the whole point of having no insulation hindering the flow. Exactly what you want. Insulation on the outside to slow the heat coming in through the walls. Concrete on the inside so it can quickly react by absorbing the interior heat. The studies have already proven it. You have not. You have not given logical explanations or built up any knowledge base. It is all supposition.

Posted By Lbear on 14 Feb 2012 12:45 PM

Posted By jmagill on 14 Feb 2012 06:35 AM


What you think and what the facts are are two different things. Having all the insulation on the outside doubles the time it will take for the heat to move to the interior wall.Having no insulation on the interior wall allows the concrete to react faster to the heat in the room, the whole point of having no insulation hindering the flow. Exactly what you want. Insulation on the outside to slow the heat coming in through the walls. Concrete on the inside so it can quickly react by absorbing the interior heat. The studies have already proven it. You have not. You have not given logical explanations or built up any knowledge base. It is all supposition.

While having the entire mass on the inside with no insulation is the ideal scenario, as shown by the studies, it still does not mean that ICF is completely useless in the thermal mass department. The concrete in ICF does contribute to thermal mass, just not as ideally as a SCIP would.

Where does that live one with? SCIPs, which are even harder to find a qualified SCIP contractor and the costs of SCIP are even more than an ICF home. Also, many people like a drywall finished interior, so having a concrete wall on the interior will turn off many people. Each system has its pros and cons but ICF claiming that the thermal mass in ICF is of no consequence is not accurate either.

Posted By jmagill on 14 Feb 2012 12:56 PM


I completely agree. Mass in an ICF wall has benefit. It however is less benefit than having the mass completely with in the insulation. We just happen to have a few ICF contractors who can not live with that benefit and have to try to claim more. It is kind of like the whole claim of 5 inches of foam and 6 inches of concrete equaling 50 rvalue.

Posted By BrucePolycrete on 15 Feb 2012 08:05 PM
We will stipulate that 5 inches of EPS is R22 - 23. Any ICF manufacturer claiming their 5" thick EPS product is anything else is being deceptive. I would be surprised to learn that any of them continue to do so. This is not debatable, it's fact.

ICF has many other benefits that make it a superior choice over a flimsy stick built wall. Avoid stick built walls, they attract tornadoes, hurricanes and fire.

Posted By toddm on 15 Feb 2012 07:50 PM
That's some study you found, Lbear: basically it is ICF-is-better-than-crap-production-houses I with a double deception baked in.

An R50 cavity stud wall would require -- what? -- 2x16s? One suspects that 5 minutes into a real world exercise, the designers would be adding foam board sheathing to the exterior or drawing up a double stud wall, either of which would dramatically improve whole wall figures. This is the fundamental deception in the ICF industry's ongoing better-than-crap campaign. Yes, whole wall numbers are the important ones. No, you don't have to pour concrete to improve them.

But real howler here is the mass effect adjustment. CTL used a code compliance program for commercial buildings to account for ICF's mass in the 38 cities. The engineering firm disclaimed it thusly: such use "may not be applicable to residential buildings; however, in our opinion, it is adequate for comparison purposes." Alas, it is not adequate as a base for insulation claims, so you will find ICF literature saying "performance up to R50" while it rates the blocks at R20ish.

One would hope that the average attentive consumer would ask why, if R50 is legit, the company says R21. The above average attentive consumer might also ask why the CTL study didn't use the Department of Energy's modeling software, developed at Oak Ridge National Laboratory for the specific purpose of quantifying mass-enhanced R values.

Could it be that the result would fall far short of R50, and embarassingly so?

Posted By toddm on 16 Feb 2012 12:26 PM
I am not inclined to guess about what's reasonable for ICF's mass effect in Phoenix, and I certainly won't accept anything the industry says about it short of proper testing.
If form companies could claim mass-enhanced values in the 30s, you'd expect them to do so, no? Here is hybrid ICF manufacturer Rastra doing just that: http://www.rastra.com/ThermalPerformance.html

Posted By toddm on 16 Feb 2012 05:00 PM
I guess I am missing your point about fiberglass. Testing doesn't catch its flaw so all testing is bad? That's silly. Or ORNL's mass effect testing specifically is bad? Possibly. Let's see some research indicating so. Otherwise, that the ICF industry ignores an accepted test while tossing around anecdotes and sketchy science is a completely different kettle of fish. If a seller won't provide me information by accepted standards, how is it my duty to guess?

But just to make you happy, yes, ICF will have a mass effect in Phoenix. I showed you an ORNL chart that suggests that R17 ICF would be a mass-enhanced R28ish. But R22 is still a jump ball. I also showed you an ORNL chart showing a decline in annual energy savings as ICF R value increased. It makes sense that more foam would push the wall's response time beyond the diurnal cycle that generates savings. But that's conjecture and we've had enough of it on this thread to last us a lifetime. If I were committed to ICF, as you appear to be, I would be quite upset that form makers are withholding information I need to make good decisions.

Posted By Lbear on 17 Feb 2012 04:09 AM

Posted By toddm on 16 Feb 2012 05:00 PM
I guess I am missing your point about fiberglass. Testing doesn't catch its flaw so all testing is bad? That's silly. Or ORNL's mass effect testing specifically is bad? Possibly. Let's see some research indicating so. Otherwise, that the ICF industry ignores an accepted test while tossing around anecdotes and sketchy science is a completely different kettle of fish. If a seller won't provide me information by accepted standards, how is it my duty to guess?

But just to make you happy, yes, ICF will have a mass effect in Phoenix. I showed you an ORNL chart that suggests that R17 ICF would be a mass-enhanced R28ish. But R22 is still a jump ball. I also showed you an ORNL chart showing a decline in annual energy savings as ICF R value increased. It makes sense that more foam would push the wall's response time beyond the diurnal cycle that generates savings. But that's conjecture and we've had enough of it on this thread to last us a lifetime. If I were committed to ICF, as you appear to be, I would be quite upset that form makers are withholding information I need to make good decisions.

The point about fiberglass is that it is still toted today that R-13 batts are actually R-13, when we know they are NOT. Yet nothing is done about this and many people still buy the R-13 misinformation and manufacturers can still sell R-13 at Lowes and Home Dept and nobody calls them on it.

EVERY building method has sketchy data at times. While the lumber industry is the predominant building technique in the USA, it is far from being truthful and honest in its claims. Without getting into all of their questionable claims, we can spend all day on how the lumber of today is of lesser and lesser quality due to the young growth trees they are using. Get a "straight" 2x4 at Lowes, leave it a garage for a month and you no longer have a "straight" 2x4.

Even SCIP has its problems and questionable data. Again, not to go off topic but SCIP builders claim the cost to do SCIP is equal or less than a wood framed home. When I got quoted for SCIP it was off the charts expensive. There is no way it equals or is less than a wood framed home cost to build.

The point is that ALL manufacturers make questionable claims and they ALL like to trash the opposing methods. It's like the Ford vs Chevy debates. Each claims their vehicle is better and each one has reports and studies claiming theirs is better. It never ends.


I ask again, what are my options? Wood or ICF? Which would you choose? You know you would pick ICF.