Looking for some insight on using strawclay as the thermal envelope for a 2 -3 story home in Michigan.
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This home needs to achieve Netzero as we are shooting for Living Building Challenge. Wondering about strategies, hesitations, cautions, or any thoughts at all. Note this is not strawbale but if you believe that work better, let me know!
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Is strawclay just cob? Sounds like it. My understanding is that cob has extremely little R-value. Its main thermal attribute is lots of thermal mass. Thus, it is best suited to warm climates where it is useful to average out the 24-hour temperature swings. A colder climate like Michigan needs plenty of R-value, because thermal mass in the walls isn't that useful when it's just constantly cold out. Strawbale seems to be the natural material of choice in colder climates. It offers a modest R-value per inch, combined with lots of inches.
There's a great article about thermal mass on GBA: https://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-thermal-mass
Brett,
I agree with Nick: If you are looking for a high-R wall made of natural materials, straw-bale walls make the most sense. For more information, see Straw-Bale Walls.
Thank you Marin & Nick for your input, that article on thermal mass was very helpful! We are looking at using a strawclay system (no sand) like the Econest, http://www.econesthomes.com/natural-building-resources/faq/
It apparently has an R value 1.5 to 2 per inch and we are looking at 12 - 15 inches. What is also important is that we use a lot of untrained volunteer labor to build this thing. We have been told strawbale will take a little more skill than strawclay and could not use as much volunteer labor. We also hope to get the ACH 2 with plaster inside. Would recommend, if we stayed this course, to put any other type of insulation on the interior or exterior?