I would like to start a discussion about this type of building material. It was invented in Sweden around 1920 because of a shortage of timber and basic wood products. It has tremendous potential as the US is experiencing what Europe went through many decades ago...shortages of basic materials. We are all experiencing a shared goal now of being energy efficient while being practical in terms of construction technique. This product seems very good. Please post a comment. I am a home owner/builder and I sell no products. I am just looking for the very best that there is.

URL for some proucts for information:

 http://www.e-crete.com/finddistributer/index.htm
http://www.safecrete.com/

Hi Jim, Aerated Concrete was created first, which took roughly 2 years to dry out the material and later improved by the Steam Curring Process in Sweden which changed the 2 year wait to 12 hours. AAC is the best solution to todays sustainability dilemma. No other material stand alone can beat the benefits of AAC's fire resistance (1inch=1hr FR rule of thumb) thermal efficiency r-20, Mold & Moisture resistance (millions of air bubbles make this material float in water) and the walls are the best breathable wall system allowing vapors to pass through the material. Energy efficient, %100 green building material that resources are abundant in our environment. I work for a distributor of AAC Products and Construction Services with over 23 years of experience with AAC. You may visit our site at http://www.mhe-international.com ....

Do you have testing(by an independent source like ORNL) to support that claim?

I see a lot of AAC being used in the southwest and southeast. How about the northeast? I'd also like to see an energy efficiency comparison to SIPs, ICFs, and stick built. Also cost comparison for equivalent size homes.

Typo Correction r-20 without additional Materials. Also listed in links below you can read about AAC out performing other building materials with extra inches of insulation yet still consuming more energy than a wall built with AAC.
I would like to direct you all to the links below. Testing Sources and comparison of energy consumption in different climates.

http://www.mhe-international.com/aac/material_advantages/thermal_efficiency.php
http://www.mhe-international.com/media/pdf/thermal%20performance.pdf

AAC,

Why would the material have a lower rate of infiltration?

Very respectfully,
Larry

Hi Larry,
The AAC - building system also provides an airtight envelope, which is critical in controlling the comfortable and healthy indoor environment. A major emphasis in heating and cooling system design is to minimize "uncontrolled" ventilation air. By providing an airtight building envelope, AAC minimizes the "uncontrolled" air changes and allows the ventilation air to be "controlled". Overall, the volume and quality of ventilation air can be easily and accurately controlled in an AAC building - thus providing a comfortable, economical and healthy environment.

A wall of AAC block is solid with no seams. A wall made of 2x4s, plywood and drywall insulated with fiberglass has many tiny cracks where air can flow through.

I was just reading about AAC blocks that are used to make ICF walls. Here is a link http://www.e-zblock.com/. I was wanting to learn more about ICF and came acrose a web sight about concrete homes. e-zblock was one of the adds. this is the web page for the concrete sight. http://www.concretehomesmagazine.com/index.php?option=com_content&task=view&id=180&Itemid=30. Has anyone on here ever used this system. How does it compair to a straight AAC wall?

Wonder how the AAC icf blocks compare to foam blocks.

Source: http://www.reddiform.com/epsfacts.htm
Is EPS foam toxic?

----According to National Bureau of Standards Combustion Tests, data collected from seven labs concluded that under the worst case fire scenario, fumes from EPS are no more toxic than those from wood. ---

Why use a product that will give out fumes during a fire? AAC building material will not catch on fire and will not emit fumes.

ACC,

I'd thought that ACC was the material from which CMU type blocks and ICF type blocks could be made.  It's clear that a left-in-place form would reduce infiltration; it's not clear that being made from ACC makes any difference on the infiltration. 

Larry

"I'd thought that ACC was the material from which CMU type blocks and ICF type blocks could be made. It's clear that a left-in-place form would reduce infiltration; it's not clear that being made from ACC makes any difference on the infiltration. " ------- No. AAC is concrete that is mixed with aluminum powder or paste. The chemical reaction makes it get tiny gas bubbles in it and it gets cured in an autoclave. Because of the bubbles it is much lighter and it insulates better. It is not mixed on site and poured into ICFs. CMU is just normal concrete.

There will be at least one AAC home in the Northeast by this time next year. It is a calculated gamble on my part. There are good reasons why AAC is rare in these parts, not least because the nearest plant is in south central ga. A wall of 8 inch block could have an r value as low as 7 depending on structural requirements. Boosters add in thermal mass equivalency to get values in the 20s. But while mass can be a major factor in dry sunny climates with big swings in daily temperatures, that's not Pennsylvania in July or December. (You'll find equivalencies by city here: http://safecrete.com/aac/products/techmanual/pdf/thermal.pdf) Yes, AAC makes for a tighter building than stud walls, but so does ICF.
I am using it anyway because it should be friendlier than ICF in a DIY project. You build it with thin set mortar and a rubber hammer, not unlike setting ceramic tile. The manufacturers claim tolerances of a sixteenth of an inch. You can slap plaster and stucco directly on the block. In stucco, you have the architectural range of EIFS, but without the disaster you risk in screwing up an EIFS application over stud walls.
I think I can make thermal mass -- and a long bank of south facing windows -- work for me. UCLA's HEED energy modeling software suggests that I'll have little heating or cooling load between Feb 1 and Nov. 1. (Humidity remains a big issue in midAtlantic summers.) Alas, concrete walls and grey skies in the remaining months bleed heat to the point that HEED shows better overall results with well insulated stud walls.
My answer: a small house, a wood stove and systems to distribute excess heat through the building. The $64 question is how many fires/sunny days per week are necessary to keep the temperature in a range of 65 to 80. If the answer is two or three, this will be an inexpensive house. If the answer is five or six... Well, it will still be an inexpensive house. As a plus, nothing gets your day started faster than a cold stove in a 50-degree house.

I am in the same position in Eastern, Washington State. Cold winters and hot summers. Sustaining the temperature of the thermal mass over 3 months of freezing weather is a challenge. Cooling will be easier as the mean temperature is 55 degrees. For buliding codie requirements for R-value, how do you plan to get the plain wall high enough to meet code? I have been pondering this question also. Do you insulate inside with furring, or outside? I like the idea of having the HTM contained in an insulation envelope, but then it ruins the exterior look that I like. Inside or outside?

Like most states, Pa makes an exception for alternative construction: R-5 for concrete walls; R-1 for log walls of 8 inches or thicker.
You don't add extra insulation to AAC. Putting it on the inside defeats the HTM principle. I'm not sure how you add it to the outside, short of an EIFS finish over a weep screed. AAC breathes, and requires special stucco, plaster and paint.
I suspect you'd have fewer issues adding insulation to Apex Block http://www.apexconsys.com/, which is a mix of concrete and reclaimed EPS and effectively a closed cell approach to light concrete. I haven't investigated it beyond the cost of shipping it from Arizona to Pa (prohibitive.)
Don't know if you have found UCLA's energy software, including Climate Consultant 4. http://www2.aud.ucla.edu/energy-design-tools/ The money graf is called the Psychrometric chart, which totes up estimated contributions to heating and cooling by various energy strategies, specific to the closest weather station. (Hagerstown, Md, in my case.) Passive solar high mass stops working here at 50 degrees.
HTM still works if you have an inexpensive source of heat to store in it, but I have to confess that I am not being rational. I want window walls; the rest is how to live with them.

I checked out the HEED calculator. It's a nice tool, but it just confirms what I have researched. I will build for passive solar, have a propane fireplace for simplicity (high output), with a wood stove backup. I will have to heat in Omak and cool some in the Winter. How much will depend on how well I insulate, etc. I don't think perfection exists, some energy has to be used. Conserving as much as possible with good building science and adherence to common sense helps. I'm about in the same lattitude and climate as your are PA (Lat: N 4827.9 Long: W 11931.1 Elev: 1305), but much dryer. I like the ACC concept enough to just build thicker walls with 12" block or better if they make it. The roofing system is what I still have to research. I want the simplest and highest R-Value that I can afford.

The problem with computer models is that "average" is rarely average. The extremes are what people remember from the last blush of passive solar building 30 years ago: the bright, warm days that turned light-mass homes into solar ovens. To me, AAC is designing for the worst case, not unlike building to a winter design temperature. I am not giving up a great deal. Even with R-10 walls, I beat code in Rescheck by 17 percent. The major heat loss in my design, not surprisingly, is windows rather than walls. Don't skimp there. (Consider roman shades for the opposite extreme of bitter cold; some claim r values as as high as 7.)
Don't know if you have found the design tools at builditsolar.com. Also, Google has a free, very slick 3-D CAD program at sketchup.google.com that works in conjunction with Google Earth. Build a model of your house, drop it onto a satellite map in its proper orientation and you can see how the sun hits it at any hour during the year.

I think the trick is balancing window area/orientation with proper thermal mass in a tight insulated envelope.