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.

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.

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 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.

Thanks, I will give it a try.

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.

--

Tex - I don't think the R15 has any bearing on the end result. The R15 is just a value they collected using a guarded hot box method. Not many people on this forum accept the results generated by this method for fibreglass insulation so I'm not sure why we would accept it here. Still it does give some overall characteristics. Never the less the R value is just for reference the actual data collected is apparently by electrical meter.

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?

"Monitoring and analysis were performed by the Oak Ridge National Laboratory with support of the Insulating Concrete Forms Association and Loudon County (Tennessee) Habitat for Humanity, Inc."

Probably just financial support. Most "scientist" would not want "layman" working on their experiment.

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 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.

Now Bruce - the way I see that is that it is blatant advertising and does nothing to enhance this thread.

You asked about an R15 ICF. We aim to educate and inform. That's all...

Lbear, you'd be silly not to investigate high mass in AZ. You might look at Rastra and Apex, both of which have plants nearby. I think the former Dow concrete-insulation-concrete operation has a plant in Colo. Hebel has an AAC plant in Mexico. Another approach is cast in place concrete with exterior foam inserts, or cmu sheathed in foam.

In AZ you get more benefit out of mass walls than in temperate maritime climes, but the benefit relative to energy use & peak loads is still lower than attending to the site-factors & orientation, glazing selection sizing, etc.

The benefit of mass walls is pretty good for mid-winter upper-midwest conditions (zone 7 and the cooler parts of zone 6) where the diurnal temperature swings are far more radical during the peak heating season than at any time during the cooling season. But again, it doesn't magically trump the other design factors.

Pissing and moaning about the differences between the original plan and how the ORNL houses were actually constructed is pointless. The DOE2 modeling was done on the as-built houses, and the measured results were well within the normal error bars of using any 2D thermal transfer model (like DOE2), with fairly close conformity of modeled to actual performance. If you want to know what ICF would do for YOUR house, model it. Anybody who really cares about the thermal performance of a house can and SHOULD model the building for the construction, site, and climate factors, and re-orient & adjust as-needed. (Which is what TexasICF does to validate what he experiences in his & his customer's places, right? ;-) )

R15/16 ICFs were available from multiple vendors in the 1990s. (Repeatedly) professing ignorance of that fact doesn't reduce the credibility of the ORNL test, but it's surprising that someone in the ICF biz would be so quick and adamant in professing that ignorance. The point of the test was to compare a lowest-cost closest to code-min house to an identical (or nearly identical) code-min stick built. That may have shortened the potential vendor list for the ICF end since most have gone higher-R on their min-R product, but so what? An R15 ICF was probably the least expensive example available at the time, intended to prove the point that "our bottom of the line is better than standard practices bottom of the line." Iif you really wanted the product used an the concrete spec you could probably get that with a phone call or emails to the relevant people at Oak Ridge. (More detail may be available online, but I haven't dug very hard for it.) Implying that the product didn't or doesn't exist (or isn't currently available) doesn't invalidate the result. Mis-stating or mis-calculating a factor that fundamental would never have passed peer-review, and if it were wrong, the industry sponsors would have been all over them to correct it.

Vented attics were required by code in most places at the time those houses were built, even if it's a bad idea in some places, and a good idea in others. (In Knoxville's climate it's a "depends" situation, but I too would opt for sealed attic there, to better limit infiltration rates, and drier average attic conditions, particularly in summer.)

The heat gain/loss of a vented vs unvented crawlspace at code-min ventilation area with a batt-insulated (~R18 whole-assembly) floor above is pretty miniscule in Knoxville's climate, and would not likely change the whole-house energy use picture by even 1%. It might be over 0.25%, but without access to the model it's hard to know for sure. It's more of a game-changer on the moisture performance relative to the susceptible wood used than the thermal peformance. At the measured infiltration rates the effect on the latent load to the conditioned space is "in the noise" of subtle differences in the efficiency of the AC system.

Seat of the pants "experiences" do not make good science, and is not a measurement. The ORNL twin-house test isn't perfect, but not bad, and DOE2 and similar energy-use models are pretty good at modeling mass effects. In lieu of actual data, I'll still take the model's output over a vendor's claims. YMMV

FBBP: Most building scientists COUNT on "laymen" with experience at the relevant trades to do the implementation and to verify that it was done competently in accordance to standard practices. But they probably wouldn't just have the rebar-tie guys install temperature and moisture probes, or have the ICFA marketing director do all the data entry on the DOE2 models without checking. ;-)

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.    

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. They would run 10 minutes and shut down for 15 minutes, and then start again. Even the home I am in now did that. I "fixed" the problem by installing a thermostat that had a 2 degree variance. So if the temp is set to 77F and it gets to 79F in the room, the A/C kicks on and runs for at least 20+ minutes until the temperature gets down to 76F. This stopped the short cycling.

My point is that there are many variables involved and even though the HVAC numbers are supposed to be engineered, things are never the same in the REAL WORLD environments. It might look good on paper but when put to the real world test, things don't look that good.

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 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.

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 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.

Yeah, I know. It just hurt a lot and upset my retirement financial plans so it's taking a while to get over it. Just gotta grouch once in awhile! Actually, if my earlier plan to buy and upgrade a fixer-upper and then build a new home had worked out I would have really been in deep doo-doo. In that case I would have been looking to sell a house after everything tanked plus getting a mortgage at the same time. So all things considered I'm a lot better off now than I would have been in that case.

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.

I don't know if I'd ever go anything less than 2-1/2".  Reason being: 2-1/2" foam only affords enough room for a 2-7/8" deep outlet/switch box (3" if using 5/8" dw).   These boxes are only 18 cu inches, which means max 8 #14s or 7 #12s plus a device (switch/outlet).  If one was to use 1-3/4" foam, you'd have to run conduit and place electrical ahead of time to countersink them into the concrete.  What a hassle and it could be a nightmare if something wasn't accounted for.  It's already a hassle working with 18 cu inch boxes instead of the 22.5 cu inch boxes that allow 10 #14s and 9 #12s.

Here's a website for easy fill calculations:

http://www.constructionmonkey.com/calculations/electrical/boxfill.aspx

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.

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

At the home I am currently in (4,000 sqft/ 2-story), it has 2 A/C units/zones, they are 3 ton units EACH for a total of 6 tons. During summer (June - October) when temps are easily in the 100F's, up to a record breaking 121F on July 20, 2011, my A/C bills run at $200-$300 a month. This is on a 2x4 wood home with R-13 fiberglass in the walls, 1" EPS exterior, and R-40 in the attic, with the air handler and ducts in the unconditioned attic where it can reach 140F.

My electric bills are not that bad when you look at the type of home it is and the outside temps. I think what helps it tremendously is that it faces North/South and the sun goes directly over the home during summer and I have no windows on the east side and only a few windows on the west side but they are shaded by a tree. I personally know people that pay $500 - $700 a month on their electric bills during summer, their homes are older, have less sq. footage and face East/West and they have old windows.

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.

The problem was that the thermostat would react to a 0.5 - 1.0 degree variance. So if the temp was set 78F, the A/C would turn on if the room temp reached 78.5F and then it would shut off at 77.5F.

Humidity? Was is humidity? Our here in the AZ desert most of the summer we see 10%-20% humidity levels. The only time we see elevated humidity levels is during monsoon season.

Regarding this home I am in now, there was no way to "fix" the short cycling except to get a different thermostat that allowed 2+ degree variances. This bumped my A/C run times from 10 minutes ON - 15 minutes OFF, to the new times of 20 minutes ON - 30 minutes OFF.

I think an overlooked issue is that the EXTREME high temperatures we experience, it requires the engineers to up size the units to make to sure they can handle 115F temps. So while my A/C units are "over sized" when you look at the temps in the 90F's but they are not "over sized" when you look at the temps in the 115F+ range. If you calculated the tonnage based on 90F-100F, then the system would be overworked when it hit 115F - 120F.

Just once I'd like to see someone post something positive on one of these forums.

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.

I believe I am positive, that is why I am 80% sure that I will build with ICF, the 20% is with wood frame.

I think the hostility or anger that some people put out there is due to the exaggerated claims that ICF has made in the past. Not you specifically, but the ICF industry has made some out of the world claims that hurt its credibility. The R-50 values and the 80% reduction in energy costs are just two of them.

I believe if the ICF industry was more conservative in their advertising, it would do away with a lot of this backlash.

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?

No. The compressor motor is a variable frequency drive and is powered through an inverter that converts the incoming 60 Hz power to a range of 52 Hz to 177 Hz. The incoming power is modulated to what is needed to run the compressor at the desired speed. Low speed, less power draw, high speed, greater power draw. You can't equate the operation of the Daikin to an ordinary heat pump or ac unit. It's billed as a variable refrigerant flow system, i.e., the more heat that needs to be moved the more refrigerant gets pumped around the circuit. Remember, the electricity that goes into the compressor during heating cycle becomes part of the heat input into the house.

My power bill is on level pay of $204/month. In Dec the actual bill was $177 and Jan it was $214. Somewhere around half of that is for cooking, TV, computer, hot water and so on. I like long showers hence the portion attributable to water heating is probably on the order of $40 to $50/ month, maybe more. My power bill is higher than what I expected it to be. The water heating part of the energy goes down the drain almost entirely, but all the rest of the power eventually degenerates into heat that helps to heat the house in the winter and adds to the cooling load in the summer. The whole heating/cooling balance in an ICF house is more complicated than for older frame houses because of the increased insulation and reduced air exchange. I don't know how many HVAC guys take into account the heat from normal living activities, but in an ICF house, and any other super insulated tight house, it can become a significant percentage of the heat source or load.

Lbear, what you describe about sizing the units for the extreme temps of 115°F is what most guys do, and what Manual J more or less dictates. Manual J requires the use of a design temp for cooling that equates to the temp exceeded about 4% of the time. In other words, a correctly sized system will not keep the house cooled to the set point temp about 4% of the time. What I did for the heating side of the calculations, which is the predominant load here, is obtain the hourly temps for a 30 year period. I then selected the temp where about 10%, I think it was, of the readings were colder, and used that as one of the design points for the heating part of the heat pump capacity requirement. The idea is that below that temp I would run a pellet stove for auxiliary heat. But available equipment sizes didn't fit so the heat pump I installed will carry the house down to 0. The Manual J temp was 9°F, and the 10% temp was about 18°F.

It's not quite as easy to do in the cooling side of the equation because auxiliary cooling units are not as practical to include in the design as is auxiliary heating. It is worth looking at though. You may find, say a 4 ton cooling system, will take care of your cooling load for 85% to 90% of the expected temps. Permanently installed, or not, window a/c units or some such coolers may be practical to include in your design to take care of the peak loads. In other words, don't automatically assume that the main cooling units outdoors, be it one or two, are the only way to attack your cooling needs.

Now with the Daikin, and Mitsubishi systems, and one or two others now, you can install one or two 3 ton units outdoors and individual units in the rooms indoors. It's called a multi-split system. The Daikin outdoor units will carry up to 130% of the rated capacity in attached loads, i.e., you can have 7 or 8, 6000 Btuh evaporators scattered thru the house connected to one 36,000 Btuh condenser. The condenser won't drive all 8 units at 6000 Btuh at the same time, but it will drive all of them at ~4000 Btuh. A system like that will give you a lot of flexibility in the design and use.

In my case I have the 3 ton outdoor unit connected to a 9,000 Btuh wall unit in the garage and a 36,000 Btuh "ceiling mount" unit in the crawl space. I don't use the garage unit very much though because if it is the only one of the two running the efficiency of the condenser drops to the point where it costs almost the same as straight electric resistance heat.