I am curious - For those of you living in ICF houses in cold climates, what are your interior wall surface temperatures (of external walls)  compared to the interior and exterior air temperatures?
e.g., outside air temp = 10, interior air temp = 70, interior surface temp of external wall = 67 

Bruce

I used to shoot them with a temperature guage after the people moved in, I never had the temperature exceed a 2 degree difference and that was right around the window area, middle of the wall it was the same interior and exterior.


It was a great sales tool consider stick frame could be over 8 degree difference interior wall to exterior.

.................but you are in sunny California ;-)  How cold is it there?

That is the info I am looking for, but with an exterior temp of 0F.

Bruce

I used to live in Ontario Canada

Bruce - We had actually buried a tempeture probe in a ICF wall back in 1991 (our first installation) here in St. Louis, Mo. Got a strange climate here - was 60 degrees the day before yesterday...and we are expecting a low of 8 degrees tomorrow and it is expected to stay below freezing for at last 3 days. Will drive by and report results back to this board...

I wounder....does it matter if the outside temp. is say 100 degrees or 20 degrees...would the proformance of a ICF wall not be the same since concrete is a solid mass able to store both heat and cool energy equally?

After 2 or 3 days of constant cold temperatures your "thermal mass" is in a relatively steady state (it will damp daily highs and lows) and what, if any, benefit there was, is gone.

Having "thermal mass" buried between two layers of insulation largely defeats its purpose.

So in my view, yes, it does what the outside temp is, but I am axious to hear what your data says.

Bruce

I hope you have a perfect interior vapor barrier, because you have a double vapor barrier on the outside.

After 2 or 3 days of constant cold temperatures your "thermal mass" is in a relatively steady state (it will damp daily highs and lows) and what, if any, benefit there was, is gone.

Having "thermal mass" buried between two layers of insulation largely defeats its purpose.

So in my view, yes, it does what the outside temp is, but I am axious to hear what your data says.

Bruce


Bruce - sorry about to delayed response. First of all the ICF Wall make-up was a 2" EPS - 6" Concrete - 2" EPS flat panel system. 1 X 3 Furring strips were added prior to the pour using 4" screws (for drywall attachment) thus creating a dead-air space of 3/4" between the inner EPS and the drywall. Temp. readings were as follows: 1.) Interior temp @ 72 F (steady - this is a medical office addition - 2 story +/- 1800sqft total) 2.) Temp. between interior EPS and the Drywall = 70-71 F 3.) Temp probe (lowest on 17/1/09) was 67 F.

The roof was conventional; however instead of fiberglass insulation, EPS, cellouse or Foam we have used Astrofoil (some referr to this as "voo-do insulation) but after 17 years I must respectfully disagree.

I tend to agree with you in regard to a thermal mass which is insulated on both sides (symetric ICF vs. "Lop-sided ICF - say 2" EPS outside; 6" concrete with 3/8" MgO2 board on the interior) something which we will try on our next project - along with a "water tubing system" as well as a underground "Duct in Duct - flow/counter flow air exchange - quite well described in "crawl space or not".

Our Target is to achieve less than 10 Kw/H/m2/year. This has been done in Europe (Poland) and can't see why this should be any different here in the U.S.

As always I respectfully welcome and look foward to your professional input.

P.S. Know Mannheim quite well...as i'm a 1973 graduate of Mannheim American High School

Thanks!

If I understand correctly:
Inside temp  = ±72°
Drywall/ICF Cavity Temp = ±70-73°
Temp Probe = ±67°    Is this the concrete core temp?

Where is the project?  What was the outside temp range over how many days?.......and what is on the outside of the ICF? 

I would have intuitively thought the core temperature would be lower unless it had not yet reached a steady state.......which could also mean that  the '2" of thermal mass/day' concept is not true, either.  I once found a thesis that a grad student did that talked about some of these issues...I'll see if I can find it.

Interesting stuff in any case.  I wish I had a big laboratory!

There has been enough practical experience with the technologies you mention to convince me that what you want to do is definitely possible.  The hard part is doing the correct sizing calculations.   I think the secret for ultra low energy houses is:  "If some insulation is good, more insulation is better and too much insulation is probably right."

Bruce

Bruce,

Have you seen a study done on a multi-unit residential by the Canadian Central Mortgage and Housing Corporation?

Over a period of several winter months, the temperature of the concrete core of the building under study barely changed at all while the exterior temperature varied by more than 20 C degrees.

https://www03.cmhc-schl.gc.ca/b2c/b2c/init.do?language=en&shop=Z01EN&areaID=0000000127&productID=00000001270000000041

Check it out. It's free.

rgb

I had not seen that study.  Thanks for the link!

An interesting article and the conclusion confirms my opinion about the performance of ICF.

Bruce

"Conclusions

The ICF wall assembly studied in this research project had an

insulating value that was fairly close to the nominal insulation value of

the polystyrene layers of insulation. While minor thermal bridges

through the wall system were detected, the more severe bridges that

were found were due to penetrations through the ICF system and did

not represent a weakness in the ICF wall system.

No thermal mass impact or higher effective insulation value was

observed. However, the air leakage testing found the building to be

relatively airtight and this can, for the most part, be attributed to the

ICF wall system. The energy savings associated with the reduced air

leakage alone are significant and would continue to accrue over the

life of the building as the amount of air leakage through the ICF wall

section would not be expected to increase to any great extent over time.

Additionally, the ICF wall system provided a significant thermal buffer

between indoor and outdoor conditions, which would provide for

enhanced comfort conditions within the building."

"No thermal mass impact or higher effective insulation value was

observed."

That report should have included the individual temperature readings.

0f course just because this study did not observe the effects of thermal mass doesn't mean it doesn't exist. If the temperatures were relatively steady inside and out, it wouldn't have an effect.

I'm sorry, but that statement is just hilarious.

The study simply confirms the results of other studies: Thermal Mass is a moot point in cold climates.It also confirms that an ICF wall, even in cold climates, will save you energy through reduced air infiltration. Again, the same as previous studies...

That's the second study I've seen that shows the effect of thermal mass is non-existent in cold climates. It just makes sense if you think about it for 2 seconds. There are plenty of other reasons to build with ICF even in cold climates, you shouldn't have to continue to propagate a myth. Don't BS people about thermal mass in cold climate (really, any environment where the exterior temp remains below (or above!) the interior temp for extended periods of time. I live in a 9000+ degree heating day climate, and I'm still strongly considering ICF for all the other benefits. Excluding the thermal mass shouldn't be a dealbreaker, so don't lie to people about it.

From CMHC/SCHL Tech series 07-119:

1. "The indoor air temperature (IAT) was maintained at approximately 19.4 degrees Centigrade (66.92*F).

2. "The temperatures on either side of the concrete were relatively stable over the three months, varying only by approximately +/- 3.5 degrees Centigrade from the average.

3. "The temperature at the interior surface of the concrete was never higher than the temperature on the interior surface of the insulation.  Hence, the heat flow never reversed direction such that the concrete transferred heat to the interior of the building even though the walls did appear to absorb some solar energy under certain conditions.  While the presence of the absorbed solar energy would reduce heat loss, the overall impact would not be significant."

If I understand correctly:
Inside temp = ±72°
Drywall/ICF Cavity Temp = ±70-73°
Temp Probe = ±67° Is this the concrete core temp?

Where is the project? What was the outside temp range over how many days?.......and what is on the outside of the ICF?

Bruce

Glad to have a Snow day here in St. Louis so I can catch up on my E-mails.

1.) The project is in St. Louis Mo. and was constructed in 1991.
2.) Outside temperature over three days remained below 32 F (0 C) with temps (as is common here in St. Louis) surpassing 50 F on day 4.
3.) The exterior finish is a 1/4" Faux Brick consisting of fine sand, perlite and a poly-elastimiric binder over 3/8" cenemtous elastic Base coal with "yellow jacket" fiber mesh.

I concur with cook90 on the fact that the thermal mass temperature would remain @ +/- 67 F irregardless or the ambient exterior temperature; no matter what length of time, since the ICF wall is in direct contact with the footing below the frost wall - or in this case with the basement footings well below the frost wall.

Therefore Delta T (between outside and interior room temperature) should remain @ no more than 10 F max (even allowing for the +/- 3.5 c which cook 90 pointed out) due to the solid mass of an ICF exterior wall.

I have no doubt that thermal mass is still a benefit of ICF walls in cold climate because of what I have experienced so far. We have an ICF house in central Minnesota that will be finished in March. It is all closed up and the current heat source is an electric plenum heater (the two stage air source heat pump is not hooked up yet). We have had drastic temperature dips this winter with it dropping down below -20 F. I can view my per day electric usage via my utility providers website. The thermal mass defintely levels out these low temperature swings. Lately our temps have peaked in the single digits. Last week my project manager turned the temp from 66F down to 55F. Electric usage dropped to near nothing for almost 2 days. This occurred when we were on a 3 day cold stretch and the average outdoor temp was -17 F. It never got above -10 F during that cold snap.
In order for there to be no benefit of thermal mass the concrete in my wall would have to be equal to the outdoor air temps. I don't think that would ever happen with the concrete wall/footing in contact with the earth down below the frost line. Plus there is the heat from the interior that would also be heating the concrete.