http://www.rastra.com/thermalperformance.html
Most climate zones have around double R-value due to thermal mass. It's claimed to be established by lab tests.
If so, I wonder why no other ICF company uses this fabulous multiplier in advertising?
Which sales department can resist selling R-20 panels as R-40 real life performance if it's true.....

They claim a multiplier of 2.05 for Minneapolis, but when I look at the ORL data, I see less than 1.4.

I'm staying in a SCIP house in a hot climate where if the house is open all night and closed up during the day, it needs no AC. So R infinity?

1.4 is 40%. That R-8 difference on a R-20 panel. Still very significant in my book.

What is ORL data? Where can I find it?

The R number is only for the one single product. That single batt of pink insulation is R-20 (or what ever size you purchase) but look at the entire envelope as a system and how well it is sealed (windows, around wood framing members, etc) to get the whole picture.

Someone told me in my area ICF 'acts' like R-38, Toronto I think is a similar climate to Minneapolis, so similar value for the multiplier.

The value of an ICF house, with a sealed insulated slab and spray foam encapsulating the attic space, properly installed windows (flashing and spray foam sealed) is one air tight structure, now condition the fresh air intake from the outside (I'm talking winter months here, since that is how I see it 9 months of the year ), or in jonr example open all night and closed all day, you have the great system.

And for years many ICF companies, or more so the sales side of it (mis-informed distributors, sales reps, installers, etc) were touting R-50, unfortunately it was inaccurate and actually probably bordered on some form of fraud or false advertising since the EPS is only R-20 or whatever some say R-22, some R-24. Currently we are allowed to promote the R value as a finished assembly, meaning ICF, concrete, drywall as each product has an R value, add masonry and an airspace and it increases again.

But having great walls and improper everything else or even one component can negate the value of those walls.

I understand all that, but still thing the R-value is useful to compare because all other things the same a house with R-10 EPS performs less than R-20 EPS.
But not even that was the point of my post. Is it possible it 'acts' so much better in certain climate conditions.

Listing a total value for the ICF form + concrete I can accept/understand (although the R-value of concrete varies too).
But the total wall? They don't know what siding I will use? Very likely I won't use drywall either. Neither they know if I do or don't put piping in the ICF wall.

So I'm purely looking for info if their 'acts like' claim is correct. Especially because, IIRC, dana1 wrote that in my climate the multiplier is close to 1.

I'm staying in a SCIP house in a hot climate where if the house is open all night and closed up during the day, it needs no AC. So R infinity?

Not infinity but good enough to stop the heat until the next cold flush during the night. If you wouldn't do that your house would likely overheat on the second or third day without AC..... ? I think smart ventilation is a whole different topic. For example only take fresh outdoor air at the time of the day it has to be heated/cooled the least.

http://web.ornl.gov/sci/buildings/2012/2001%20B8%20papers/080_Kosny.pdf
The hotter the climate the greater the benefit.
As figure 4 shows the location of the insulation is of big importance in warmer climates
Likely the test houses in the paper were quality leak proof builds. While leaks have nothing to do with mass I tend to think old concrete buildings are much less leaky than wooden buildings. The tests in the paper are very likely done on very well constructed test buildings that are very well sealed. Knowing myself if I had a wooden house I wouldn't regularly seal leaks. And that increases energy consumption a lot. Poured concrete walls never start leaking.
Something to think about for people who a lazy slackers like me. And the active people should add, higher maintenance costs to the the cost of ownership (which imo should be viewed over at least 10 years) /EDIT Forgot the most relevant point.... (Figure 4) DBMS (multiplier?) is about 1.5 for ICF in all climates. Outside only insulation doubles that in hot climates.

There is both a peak load aspect and an average use aspect to the benefits of mass walls, but the claims of ICF manufacturers are often completely ridiculous flights of fancy, starting with an overstatement of even the R-value of the EPS. It's common to see an ICF specify R4.5/inch for Type-II EPS, citing the tested performance at 40F, and even sometimes the R4.7/inch for 25F. But that 40F/35F test number isn't the exterior air temperature, but rather the average temperature through the foam. For the average temperature through the foam to be 40F with an interior temperature of 70F requires an outside temp of +10F. For it to average 25F requires an outside temp of -20F. Using the 40F R-value for EPS has some relevance in US climate zone 7, since +10F is the mid-winter average temp in some of those locations, but for most of the US +10F is below the 99th percentile temperature bin. From there they move on to the arm-waving about the dynamic benefits...

This is not a knock on ICF construction, only a knock on ICF marketing exaggeration. I'm often perceived as anti-ICF when pointing this stuff out, but that's simply not the case.

The IRC prescriptives take the energy use benefits into account (in a crude fashion) with different prescriptive R values for framed walls (with or without insulating sheathing) and mass walls (with either most of the insulation on the exterior, or at least 50% on the exterior), but do not reflect the effects on peak load, which is dynamically site and construction specific.

See: http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_11_sec002.htm

In a zone-4 (southern IN) location, note that a framed wall is required to either be 2x6 with R20 cavity fill, or 2x4 with R13 cavity fill, with R5 of continuous insulation (on either side of the wall assembly). Either one of those works out to about R13-R15 "whole-wall" R after factoring in the thermal bridging. In the same climate R8 continuous insulation would meet code for a mass wall, if at least half of the insulation were on the exterior, but that rises to R13 continuous insulation if more than half of the insulation is on the interior. That is pretty much the same steady state whole-wall R as the framed walll prescriptives.

In zone 5 (northern IN), the framed wall minimums remain the same, but the mass wall needs to be at least R13 continuous insulation if at least half the insulation is on the exterior (about the same as a framed wall), but that increases to R17 if the insulation is on the interior. That's an indication that having the mass outside of the insulation is actually neutral or even slightly WORSE than having a less massive wall from an energy use perspective in zones 5 & higher, and of only marginal benefit if the mass is more than halfway inside the thermal boundary of the building envelope.

But some reduction in peak load is still going to be there, even in climates where the average energy use is close to a wash. How much of a reduction is highly dependent upon the actual house design and site-factors.

There are no simple models that really tell the whole story, the shape, site insolation/shading, and orientation of the house all affect the dynamic performance of an ICF or other mass walls, but tools like DOE2/BeOPT (free downloads courtesy of the US D.O.E.) get it mostly-right on the energy use. Assigning a simple DBMS multiplier for any climate is nearly complete BS, since the site factors will affect it wildly. If your house is EXACTLY the shoe-box with a gable that they modeled it in the Oak Ridge studies, and oriented the same way, with the same number & type of windows, the dumb multiplier could be close. But it's far better to simulate YOUR house, not the "standard" house, (even with a relatively crude tool like DOE2) if you feel the need to get it within 10% of reality.

If there is no need to calculate it that tightly, assume that a well built ICF will have thermal performance at least as good as framed house of equivalent "whole-wall-R", and will in some cases edge it out on energy use by something like 5%. Once you're at R20+ "whole-wall", the window & door losses of code-min windows are usually larger than the wall losses anyway, but the notion that an R21 (2.5" of EPS both sides) ICF is going to have 1.5x the thermal performance of a 2x6/R20 + R8 wall of comparable steady-state "whole-wall-R" is not a good assumption. It will in some instances, not in others.

A house built to IRC 2012 air tightness (3ACH/50) is not a very leaky house, and MANY ICF houses have tested higher than that. While it's somewhat easier to reliably air seal an ICF than a framed house, it doesn't take rocket science with either (it's more like goop & tape science :-) ), it just takes attention to the critical details, a consciousness on the part of the builder that air tightness is a goal. It's not a high hurdle to hit 3ACH/50, but the additional thermal performance of bringing that down to 1ACH/50 isn't worth very much except in extremely high performance buildings (like a PassiveHouse). Performance builders have been air sealing wood-sheathed framed construction for decades, and subsequent re-testing does not show a degradation in air-tightness, particularly when the primary air barrier is the wood sheathing rather than the finished interior wall (which has more electrical & plumbing penetrations, and is more subject to puncture by the occupants.) Keeping a decently built wood house air tight that was originally built air tight does not take any more maintenance than an air-tight ICF house- it's just fine for "...lazy slackers like me...". The perception that air tight framed construction is higher maintenance than ICF is misplaced.

I put most blame on .gov for the false advertising because they have to set strict testing standards. The companies just try to survive a market in which the customer picks the product with a 0.01 higher R-value. I'll never forget the R-chart of spray foam you posted...

I don't view that marketing blah blah as a ICF issue at all. I'm convinced stick builders are great at optimizing the numbers too.


I was under the impression that the shearing of a woodframe introduced more air leakage.

I never thought about this stuff until I found this forum but I can't remember by parents every sealing their 100 year old non-leaky house. Non-leaky as in no noticeble drafts because I've never ever heard about blower door and infra red tests before I found this forum. Just brick wall and hard wood window framing sealed with lots of cement.




I took the advice of forum members and used beopt, resfen, heat2000 and some others. What I learned is that they are perfect to prove any R-value you like. Because I fully admit I haven't the faintest clue how to use those programs in a *correct* way I decided to focus on quality materials, sun orientation etc because that I slightly :-) understand.


Because those programs have no "I'm Dutch" setting they won't be accurate anyway because when it's summer here all doors and windows are wide open. Likely not what cooling load calculations are based on :-)





Anyway it isn't/wasn't my plan to build based on DBMS because I usually use the most pessimistic numbers. Even if they come from well respected labs that are paid by the industry.

I never forget a completely scientifically backed movie I saw at an airport. It turns out that traveling by plane is greener than walking because for every 666 trillion airmiles they plant a tree. To make things even greener, they don't spill a drop of kerosene when filling the almost non existent tanks of the plane. On top of that walking is criminal behavior because it robs airport people of jobs.

Posted By Dana1 on 11 Feb 2015 02:57 PM
It's common to see an ICF specify R4.5/inch for Type-II EPS, citing the tested performance at 40F, and even sometimes the R4.7/inch for 25F. But that 40F/35F test number isn't the exterior air temperature, but rather the average temperature through the foam. For the average temperature through the foam to be 40F with an interior temperature of 70F requires an outside temp of +10F. For it to average 25F requires an outside temp of -20F. Using the 40F R-value for EPS has some relevance in US climate zone 7, since +10F is the mid-winter average temp in some of those locations,

Maybe a bit due to the thermal wick effect? http://www.icfmag.com/articles/features/temp_wick.html

Posted By Lbear on 12 Feb 2015 01:04 AM

Posted By sailawayrb on 02 Jan 2015 10:05 AM

This summer effective R-value of R66.15 is 2.86 times higher than the conventional R23.1 R-value.

While I am sure some of this is not especially surprising to many of you, I am very encouraged that the program is showing this.

So it's real and very significant in some climates.
But is it in 'my' climate? If so, would using a 8" concrete core instead of 6" have a benefit that will pay itself back in a reasonable time?

A very significant factor in how much thermal mass helps is the range of temperatures the occupants can tolerate. If you use heat and AC to always hold the interior at 74F, then almost all of the benefit of internal mass goes away. And despite ORNL's largely undocumented claims, thermal mass has a significant negative effect on thermostat setback, sometimes more than enough to completely negate the savings.

IMO, "equivalent R value" of anything is far too inaccurate to be useful.

The introduction of shear loads does not create air leaks in timber-framed plywood/OSB sheathed buildings. An earthquake can, but an earth quake will open up a brick or concrete buildings too.  Acoustic sealant caulk applied between the sheathing & framing, and between relevant framing elements has a VERY good long term track record, since it stays flexible/pliable forever.

The vast majority of stick-builders don't optimize thermal performance numbers- they don't HAVE any numbers to optimize. They simply build to whatever is required by code and call it a day.  The IRC codes are reasonably fair about the real-world thermal performance of their minimums.

High performance housing archtitects & engineers use better tools than BeOpt for specifing the details of a high performance building, some even go so far as to use 3-D modeling tools to figure out the heat leakage at various corner & edge framing features (though with simple house designs that's complete overkill.)  Even the PassiveHouse spreadsheet tools are crude, but realistically predictive of real world thermal performance, and well tested with 100s of real-world homes.

I'm not sure you really want the doors & windows wide open on those few days most summers when the outdoor temperatures reach 40C, and the dew points are pushing 30C. Unlike Nederland that really does happen in Indiana. When it does, it's time to close it all up and turn on an air conditioner so that the temperature inside the house doesn't reach hellish temperatures with sauna-like humidity levels, and stay hot all night long.

The vast majority of stick-builders don't optimize thermal performance numbers- they don't HAVE any numbers to optimize.

It's not just about an R-value. Think about things like building costs. Especially when comparing to non stick building methods they 'forget' to add all sort of things to their stick-builds and maximize the prize of everything the competition does. Or take a R20 fiberglass batt and compare that with an R20 SIP. Obviously they 'forget' to mention all the framing reduces the overall R-value, Batts not cut 100% accurately or compressed lower the R even more. In my book that's just as misleading as using thermal mass numbers. I'm sure top quality work can be done with batts but it's less likely. Especially at the rock bottom $/ft2 they quote when comparing to everything not being stick. When I wrote 'optimize' it wasn't just about stick vs ICF but ICF vs every other building form including ICF vs ICF.


For me that are performance numbers because I tend to view things over a longer period of time. What is the total amount I paid in 10 years

*= building, maintenance, insurance, utils, etc

Just curious- Has anyone ever done an identical, side-by-side comparison of the different methods? If I had the money, I'd build several different structures with the same exposure in the same climate so that they could be accurately compared. Apparently, there is some difference between calculated performance and real-world experience, so the debate rages on. To be really useful, the same experiment would have to be conducted in different climates, too, so we would know which system performs best in the local conditions.

there is some difference between calculated performance and real-world experience

The numbers will vary significantly depending on the behavior of the occupants. So the debate would still continue.

IMO, the Passive House homes are pretty much state-of-the-art when it comes to excellent verified energy performance at a tolerable price point. I believe that most of them (in the US) use lots of cellulose. Perhaps because once you get to that level of insulation, wallboard alone is enough to create a "high interior mass" wall.

Posted By jdebree on 13 Feb 2015 07:02 AM
Just curious- Has anyone ever done an identical, side-by-side comparison of the different methods?

http://web.ornl.gov/sci/buildings/2012/2001%20B8%20papers/080_Kosny.pdf

I'm wondering about the combination of R-values

Is the combined R-value of 10sqft R20 and 10sqft R10 an average R15?

I would say yes but when taking things to the extreme I start doubting a bit.

An R50 wall with an equal sized R2 single pane window.

Does that average out as R26 or do other factors come into play with such unbalanced constructions?

Posted By NewHoosier on 13 Feb 2015 08:14 AM
I'm wondering about the combination of R-values

Is the combined R-value of 10sqft R20 and 10sqft R10 an average R15?

I would say yes but when taking things to the extreme I start doubting a bit.

An R50 wall with an equal sized R2 single pane window.

Does that average out as R26 or do other factors come into play with such unbalanced constructions?

No, the average is not U15.

The U-factor of a continuous R20 is 1/R20, or U0.05, the U-factor of a continuous R10 is 1/R10, or U0.10.  At a 50% fraction of each the average U-factor is:

(0.5 x U0.05) + (0.5 x U0.10)= U0.075

The average R value is then 1/U0.075 = R13.3 (and not R15 thus.)

It's a lot easier to just work with just U-factor, not R-value, which is how it's commonly done in Europe.

The U-factor of an R50 wall is U0.02.

The U-factor of an R2 window (which doesn't meet code anywhere in the US that has energy codes)  is 1/R2= U0.50.

So every square foot of R2 window loses as much heat as U0.50/U0.02= 25 square feet of R50 wall.

This is true for calculating a peak heating load, since there is no solar gain at night, which is when the peak loads typically occur.

But from an energy use point of view, the R2 window also has solar gain. With a U0.5 window it is still a net loss, but not as much of a loss as the simple U-factor might indicate.  At U0.35 or lower most windows are net energy gainers from a total energy point of view, even though the peak loss numbers are still true.  How much energy is gained is extremely site & orientation specific, and from an annual energy use one is faced with the cooling energy use as well as the heating energy use. (This is less of an issue in Canada than at the lower latitudes of the US.)