Now ... after only answering questions over the years I am finally putting out my first thread: 
 
http://www.ashrae.org/publications/page/FreeAEDG   (see K12 50% Solution)

Having now read this a couple of times it seems to me thermal bridging is quite well understood by the powers that be (and I'm not sure thats always been true for some). 

ASHRAE is holding ICF in a very positive light.

I do appreciate a high standard (e.g. the 50% solution).   Our previous standards were a little low don't you think?

Here's an example: 

Zone five (colder climate):   comparing insulation requirements for mass walls to wood frame walls.  
    
The way I read this report mass walls require a minimum of R-13.3 c.i.  (continuous insulation).    This target is quite low for ICF since the typical ICF is about R22 and yes it is considered continous insulation.  In fact, I don't know of any ICFs with R-values that low.      

Mass walls must have a minimum heat capacity HC of at least 7 BTU/ft2 F.  (which is quite low compared to ICF (concrete) which is about 23).   (( Clarification:   a six inch ICF core would have a heat capacity of 23/2 or 11.5 BTU/ft2 F))

Therefore ICF fits nicely in the mass wall definition.

Regarding wood frame -- with a framing factor of 20% and R-24 cavity you have about R13 or R12.   Then you need to add R-10 continuous insulation to the outside.   This puts things in perspective since many many builders would actually call this a R-34.

Regards. 

This is a really big deal for the whole industry. It's actually been out for three months, and this is the first I've seen it mentioned.Thanks.

Tex, Thanks for the post and link, I will read the report next chance i get.

For reading the tables for wood and steel stud walls:  I have confirmed from a couple of sources that the R-value is the cavity value and not the actual R-value of the wall.   Regards.

Any of you Canadians seen or aware of the new OBC effective Jan 1?

For those outside our area, ICF although not written as mandatory for the basement, people are about to see ICF as the best choice based on the new requirements for insulation.

Elaborate for us fellow canadians

Below grade in Ontario must now be R-24, So I am led to believe. I haven't read it fully mind you, but I also am led to believe that our R-22.4 +/- is considered acceptable as it's performance is better than 'pink' @ R-24.

Bottom line I got to see the new building permit application for Hamilton last week and they have written right on it - Is this an ICF basement and Is this ICF above grade - This is strides for us ICF contractors.

The way the plan checker explained it to me was if it shows ICF for a basement his job becomes easier as he doesn't need to review as hard and if it is ICF to the roof it's even easier for him, he just verifies the heat loss quickly and it's done...for that portion, still needs structural review mind you.

Good to know, that will help ICF builders in ontario.

Posted By Chris Johnson on 27 Dec 2011 11:59 AM
Below grade in Ontario must now be R-24, So I am led to believe. I haven't read it fully mind you, but I also am led to believe that our R-22.4 +/- is considered acceptable as it's performance is better than 'pink' @ R-24.

Bottom line I got to see the new building permit application for Hamilton last week and they have written right on it - Is this an ICF basement and Is this ICF above grade - This is strides for us ICF contractors.

The way the plan checker explained it to me was if it shows ICF for a basement his job becomes easier as he doesn't need to review as hard and if it is ICF to the roof it's even easier for him, he just verifies the heat loss quickly and it's done...for that portion, still needs structural review mind you.

With "pink" @ any R-value is a disaster for below grade applications in cold climates, and is made even worse by building codes in Canada that are often interpreted as requiring poly as an interior vapor barrier, which traps ground moisture in the studwall when an interior studwall is used as foundation insulation.

Fiber insulation R values universally refer to center-cavity R, not "whole assembly" R with the thermal bridging factored in. The difference between center cavity an whole-wall R has been well understood for at least 50 years- there is no hot news flash in that ASHRAE document. It only reflects the long understood whole-wall R values of different studwall types based on typical commercial construction framing fractions.  The mass wall "requirement" is really only a definition of the minimum amount of thermal mass to be considered a mass wall. Some types of masonry construction would also fill the bill, but others would not, but it's at least a line in the sand.

R24 pink in a 16" o.c. 2x6 studwall with a 15% framing fraction is the equivalent of about R17 continuous insulation.  The "right"  (as in "most cost effective) way to get there in most of Ontario as a retrofit, would be to use 1.5-2" of XPS trapped between a 2x4 studwall and the foundation wall and NO interior vapor retarder of any kind (not even kraft paper) only standard latex finish aint on the wallboard. That way the  XPS allows the foundation to dry toward the interior slowly, saving the foundation & foundation sill from high moisture content, reducing rot risk, and saving the exterior exposed part of the foundation from spalling on freeze/thaw cycles due to high moisture content in the concrete.  But I believe that would still be a code violation in Ontario, which IIRC still requires that the exterior foam have sufficient R value that there is no condensation on the interior face of the foam at the heating design temperature. (Which is silly, since the foam itself is the condensing surface, and neither absorbs nor is harmed by occasional fogging on the coldest weeks of the year.   Even if there were wooden sheathing between the studwall and foam, 2" of exterior foam on the above grade section would more than protect that sheathing from condensation moisture damage, with a 2x4 fiber-insulated interior.)

On new construction it's better to put all of the insulation on the exterior of the concrete from an efficiency point of view, since that keeps the entire thermal mass of the concrete inside the thermal boundary where it does the most good, and keeps the foundation warmer/drier.  Below grade the mass benefit of ICF is effectively zero, since the diurnal temperature swings are nearly zero. But with the foundation mass on the interior of the thermal envelope it buffers the heating & cooling loads of the entire house.

Posted By TexasICF on 23 Dec 2011 11:51 AM
Now ... after only answering questions over the years I am finally putting out my first thread: 
 
http://www.ashrae.org/publications/page/FreeAEDG   (see K12 50% Solution)

Having now read this a couple of times it seems to me thermal bridging is quite well understood by the powers that be (and I'm not sure thats always been true for some). 

ASHRAE is holding ICF in a very positive light.

I do appreciate a high standard (e.g. the 50% solution).   Our previous standards were a little low don't you think?

Here's an example: 

Zone five (colder climate):   comparing insulation requirements for mass walls to wood frame walls.  
    
The way I read this report mass walls require a minimum of R-13.3 c.i.  (continuous insulation).    This target is quite low for ICF since the typical ICF is about R22 and yes it is considered continous insulation.  In fact, I don't know of any ICFs with R-values that low.      

Mass walls must have a minimum heat capacity HC of at least 7 BTU/ft2 F.  (which is quite low compared to ICF (concrete) which is about 23).   (( Clarification:   a six inch ICF core would have a heat capacity of 23/2 or 11.5 BTU/ft2 F))

Therefore ICF fits nicely in the mass wall definition.

Regarding wood frame -- with a framing factor of 20% and R-24 cavity you have about R13 or R12.   Then you need to add R-10 continuous insulation to the outside.   This puts things in perspective since many many builders would actually call this a R-34.

Regards. 

To achieve a low R12 with R24 center cavity with a 20% framing fraction is only true if using only 4" of closed cell foam in a 2x6 cavity and NO interior gypsum, or exterior siding, which is literally never done. You'd hit R13+ with any standard interior & exterior finish materials. 

And fully insulating the cavity by filling it fully with much cheaper R3.3-R4/inch fiber increases the R value at the thermal bridges (the full stud depth), yielding whole-wall Rs in the ~ R14-R15 range.  If you found a cavity insulation with the right K-value to deliver R24 at 5.5" (full-depth, 2x6) the whole-wall R would be about R15.5, which is dramatically better than the R12 you posit.

The example is the world's stupidest way to utilize foam in a framed structure, and using that sort of straw man argument is a bit like selling snake-oil.  In the real world studwalls with additional continuous exterior insulation use the cheap stuff in the stud cavites. A 2x6 fiber-insulated studwall with half the amount of foam applied to the EXTERIOR of the sheathing yields whole-wall Rs in the mid 20s for far less money than your silly example.

I'm also a bit skeptical about who would refer to that bizarre  example stackup as know of no building designer or building code drafter who would actually call the straw man stackup R24 cavity-fill with R10 continuous on the exterior R34 either, but I'll grant that a clueless G.C. might.  Most of the design world specifies things in terms of average U-values for the entire wall or room (including windows & doors), and the code minimums for window fractions & types and center-cavity Rs will track a maximum average U-value.  Codes tend to specify studwalls with exterior continuous insulation as "Rx + y", where x is the cavity R, and y is the continuous sheathing R. 

For example, code min in my area for residential structures is "R13+ 5 , or   R19", both of which have a whole-wall R value of about R15.  But one is allowed to "cheat" on that on a room-by-room basis if the glazed fraction is substantially below code-max. (But why anyone would is beyond me. From a comfort and long term payback point of view 1.5x code min is an easy argument to make even on a windowless room.)

And I've yet to hear ANYONE, not even a GC refer to R13+5 construction as R18. YMMV.

So yes, a minimalist ICF meets the spec of the ASHRAE K-12 50% recommendation, but so what?  It's not always going to the the most optimal way to get there or the most cost effective, and I doubt it's going to be widely adopted in that application simply because it meets the ASHRAE recommendation.  A minimalist ICF exceeds residential code min in most of the lower 48 too, but it's rarely the most cost effective path to thermal performance in the package as a whole.  (It can sometimes be the simplest most cost effective way to build an insulated foundation to R16+ though.)

Dana1, Your spittle-sprayed contempt and loathing certainly gets your point across, but it doesn't show off your intellect to its best light. Relax. There's more to life (and ICF) than thermal performance.

For example, code min in my area for residential structures is "R13+ 5 , or   R19", both of which have a whole-wall R value of about R15.  But one is allowed to "cheat" on that on a room-by-room basis if the glazed fraction is substantially below code-max. (But why anyone would is beyond me. From a comfort and long term payback point of view 1.5x code min is an easy argument to make even on a windowless room.)

And I've yet to hear ANYONE, not even a GC refer to R13+5 construction as R18. YMMV.

So yes, a minimalist ICF meets the spec of the ASHRAE K-12 50% recommendation, but so what?  It's not always going to the the most optimal way to get there or the most cost effective, and I doubt it's going to be widely adopted in that application simply because it meets the ASHRAE recommendation.  A minimalist ICF exceeds residential code min in most of the lower 48 too, but it's rarely the most cost effective path to thermal performance in the package as a whole.  (It can sometimes be the simplest most cost effective way to build an insulated foundation to R16+ though.)

Ray, okay I suppose your right --  at least there is more to life anyway.   We all have a right to our opinion.  However, I believe that some of our communication makes it difficult for the average fellow to make an educated decision.   "R13 + 5, or  R19" implies these are the same and then -- well -- actually they're really R15.  And then "I've yet to hear ANYONE, not even a GC refer to R13 +5  as R18."  Wasn't something awfully similar just in the previous paragraph?  "R13 + 5, or R19" and we wonder why people are confused.

So yes, minimalist ICF meets the ASHRAE K-12 50% recommendation (minimalist is another neologism for me)....  yes, an ICF that doesn't even exist at such a low heat capacity (approximately 1/2 that of a 6" wall) and with an R-value that is significantly less than that assigned to wood stud and steel stud construction for the same (and all 8 climate zones actually) meets ASHRAEs K12 50% recommendation.  I think this is a big deal. 

I would encourage you (green talk folks considering ICF) to read this document.   To me it says a mass wall of R13.3 (even with substantially less mass and R-value than any ICF I am aware of on the market)  performs at the R13 + R7.5 c.i. level in zone 4.  This is assigning more than a tiny bit value to the mass don't you think?  R13.3 with mass == wood constrution R13 + R7.5 c.i. ?  Best case with whole wall semantics this is (Mass + R13.3 c.i.) is the same as or equivalent to a whole wall R17.

I believe this ASHRAE, DOE document should (and will) be taken seriously.   I don't think its an accident that the top performing school in the US is ICF.  Performing at 17 kbtu per square foot per year and energy star is 50?   The next top performing school is likely to be ICF as well based on the grapevine.

Posted By Ray Gladstone on 27 Dec 2011 07:22 PM
Dana1, Your spittle-sprayed contempt and loathing certainly gets your point across, but it doesn't show off your intellect to its best light. Relax. There's more to life (and ICF) than thermal performance.

To be clear, I don't have contempt for ICF (quite the contrary!), but I confess I sometimes lose patience with exaggerated performance claims, especially when combined with an underrating of the performance of a competing technology.

Understating the thermal performance of a 2x6 R24  studwall by 20%  (Calling it R12 instead of R15) is one of those, just as up-rating an R21 ICF to R23+ by counting the air films (as in a document TexasICF had linked to on another thread) would be overstating relative performance by 10%.  (All sorts of things look great if your model is 10% better than reality, and your description of an alternative lags reality by 20%-  sorta like web-dating profiles. )

I've read claims on the ICF forum  of R4.5 per inch for EPS, which might be true ON MARS, where the temps are much cooler, but not where most of us live.  It's not that ICFs don't have decent thermal peformance- they clearly do, but some seem to go out their way to flop a fat thumb on the scale to make the case, a fat thumb that isn't necessary or warranted.

Yes, there are MANY benefits to ICF construction- I fully appreciate the structural and acoustic benefits of ICf construction relative to many alternatives but as a wall system in a school building I'm doubtful that it'll become the paradigm for school buildings.

Posted By Dana1 on 28 Dec 2011 03:17 PM

Posted By Ray Gladstone on 27 Dec 2011 07:22 PM
Dana1, Your spittle-sprayed contempt and loathing certainly gets your point across, but it doesn't show off your intellect to its best light. Relax. There's more to life (and ICF) than thermal performance.

To be clear, I don't have contempt for ICF (quite the contrary!), but I confess I sometimes lose patience with exaggerated performance claims, especially when combined with an underrating of the performance of a competing technology.

Understating the thermal performance of a 2x6 R24  studwall by 20%  (Calling it R12 instead of R15) is one of those, just as up-rating an R21 ICF to R23+ by counting the air films (as in a document TexasICF had linked to on another thread) would be overstating relative performance by 10%.  (All sorts of things look great if your model is 10% better than reality, and your description of an alternative lags reality by 20%-  sorta like web-dating profiles. )

I've read claims on the ICF forum  of R4.5 per inch for EPS, which might be true ON MARS, where the temps are much cooler, but not where most of us live.  It's not that ICFs don't have decent thermal peformance- they clearly do, but some seem to go out their way to flop a fat thumb on the scale to make the case, a fat thumb that isn't necessary or warranted.

Yes, there are MANY benefits to ICF construction- I fully appreciate the structural and acoustic benefits of ICf construction relative to many alternatives but as a wall system in a school building I'm doubtful that it'll become the paradigm for school buildings.

Dana1, 

The document doesn't say if its a 2x6 wall or 2x4 wall etc. all it says is that an R13 + R7.5 c.i. (continuous insulation) wood framed wall performs the same as a mass wall of R13.3 c.i. in zone 4.   Somewhat similar advantages are tabulated for mass walls in all eight climate zones from florida to north Alaska.  I didn't compile these tables nor did I influence them in any way.   The subject of this thread which I started is the ASHRAE report 50% Solution.

I don't think my thumb is that fat when the table uses a mass wall of R13.3 c.i. and most ICFs have much higher R-values around R20+.   I also don't believe my thumb is that fat in saying that the heat capacity of the mass wall in the table is a minimum of 7 btu/sqft F and your typical ICF wall with a 6" concrete core has a heat capacity of 11 btu/sqft F.  

Contrary to what you might think:   I am not looking for trouble.   You are the last person I want to wrestle with on this forum... and I am actually trying to learn something from the time I invest here.  

My fat thumb or fat head aside why do you suppose:

The American Society of Heating, Refrigeration and Air-conditioning Engineers  
The American Institute of Architects
U.S. Green Building Council
U.S. Department of Energy 

put these tables and report together showing that a high mass wall (albeit a much lower mass than ICF) with a relatively low R-value (also lower than any ICF I'm aware of)  performs equivalent to a low mass wall with significantly higher R-value?   Regards.

Nobody is arguing that ICF is deficient on R value, or that the mass effect is zero.

Your assertion that a fictional R24 filled studwall is actually R12 for a whole-wall R is simply a fiction, fat thumb squishing the straw man.

For zone 4 the tables recommend R13 + 7.5 for both steel and wood framing.

That would be about R17-18 whole-wall for wood studs...

...but only about R14 with steel studs.

And the recommendation for mass walls is R13.3., less than R1 from the lowest-of-low-mass steel stud walls. (I'm wondering if the R13 + 7.5 for the wood framing is actually a typo.)

For zone 3 they recommend R13 + 7.5 for steel studs (~R14) R13+ 3.8 for wood (~R14), and R11.4 for mass walls, not a huge delta, but some.

For US zone 1 it looks like they're shooting for whole wall R of ~ R10 for low-mass walls (with the exception of the steel studs where they still spec R13+ 7.5, probably due to the severe thermal bridging of the steel), and R 5.7 for mass walls which is a bigger percentage difference.

There's larger air-conditioning benefit due to the mass of a mass wall in cooling climates, and I can believe that in zone 4 a minimal-mass R13.3 minimal-mass wall would perform similarly in many or most designs for zone 3. Yes, a minimal ICF is both more massive and higher R than the ASHRAE recommendation. The additional mass beyond the minimum doesn't buy much addtional performance, but it'll buy some.

By contrast the additional R of a minimalist ICF will HURT the annualized energy use in some designs, help in others- you really have to model it for this type of building and use to know for sure, but I'd also expect the difference between R13.3 and R20 whole-wall R to be "in the noise" relative to the big picture for most designs, but possibly real negative on some. Large buildings are heat traps, and a populated school building has a lot of ( living breathing) heat-sources. Excess R beyond an optimal value in a particular design can increase the average sensible AC loads, and annual energy use. Schools and offices are a very different scenario from single-family residential buildings where all R is good R, even if the payback falls off beyond some level.

The notion that the ASHRAE document makes a strong case for use of ICF in school buildings isn't really a conclusion that can be drawn from the wall-type recommendation tables, since for some US climate zones a minimalist ICF exceeds the recommended whole-wall R by a factor of 2 or more, and is almost surely going to add to the average energy use in many school building design. The ASHRAE recommendations are likely shooting for the middle over some range of designs, somewhere near the sweet-spot on wall R values, (and yes, it will differ with the thermal mass of the wall.) But there's no clear strong case being for R20+ mass walls being significantly superior for reducing energy use- they're asking for a lot less, for MOST of the country.

I downloaded the report and took a quick review of it, but not thoroughly. Does it discuss the impact of temperature set backs? I'm thinking specifically about schools in the Northern part of the country.

I'm wondering about this because of my experience with my garage, which is attached to the house with a common ICF wall, and has ICF on the other three sides. I use a pellet stove to heat it. What I'm seeing is that once the heat is turned off the garage drops temperature fairly quickly. It'll go from 70F to 50F in about 3 or 4 hours when it's 32F or colder outside. It stays in the 50 to 55F temp range though pretty much all the time, unless it's only about 0F or so for days on end. I put a thermometer through the foam and up against the concrete. It showed a temp around 45F to 50F. The wall surface temp is about the same as the room temp so there definitely is no "cold" wall feeling.

I'm beginning to wonder, for a garage that is heated only part time, if ICF really has a lot of advantage over a well insulated and sealed frame wall. By extension I wonder how well it will work for a building like a school. I'm sure most every school is going to set the temp back overnight and on weekends when the building is not used. Will the mass effect of the concrete, typically behind about 2.5" of foam, make Monday morning heating sluggish? Would the school be looking at having to have excess heating capacity to overcome this sluggishness?

I have a 3 ton Daikin heat pump for my house. It works great, but it is has little excess capacity, especially when the outdoor temp drops to 10F and colder. At 0F the performance chart lists its output at about 30,000 Btuh. When we first moved in I tried nighttime temp setback but gave up on it after about 3 days! Morning temp recovery was so slow. I think a school would have to contend with the same situation.

Clearview Elementary School in PA. ICF walls. US Dept of Energy's Energy Smart Schools program poster child from 2002:

"As a test, the school heating system was shut down at 1 p.m. in mid-February when the high temperature outside reached only 40°F. Nighttime temperatures fell to 22°F., but the classrooms cooled by only 4 ½°F. When the furnace was restarted at 5:30 a.m. the next morning, the desired room temperature was regained in less than an hour. Architect John Boecker, says, “The insulating concrete form wall provided us with a high-performance thermal envelope that contributed significantly to downsizing our HVAC system and reducing energy consumption.”

Read it and weep.

attached to the house with a common ICF wall, and has ICF on the other three sides.

Okay, that's four sides. Is there a side of the garage that has big doors on it, like the ones you would drive a vehicle through?

One other thing. If an R24 double framed sprayed foam 2x6 wall saves me 10 bucks a month in HVAC costs over a 6" ICF wall, I'm going for the ICF. You are arguing over pennies in HVAC costs and that's meaningless in the grand scheme of things. You should get a little perspective.

Energy efficiency is only one small part of the ICF choice.

Now I see there is more than one way to win friends and influence people.