Strawbale home

Hi,
Maybe the biggest saving associated with strawbale homes is the long term energy saving?

If you compare a stick frame wall's energy use to a strawbale wall's energy use for these conditions:
- 2000 sqft house
- 1700 sqft of wall area
- Medium cold climate (7000 degree days)
- propane fuel at $2.2 a gallon
- Stick frame wall 2X4 16OC, R11 bat insulation (actual whole wall R10 )
- Strawbale wall at R30

The saving comes out about $450 a year, and a 2500 lbs reduction in CO2 emissions.
If you assume 10% per year fuel price inflation per year, the saving for the first 20 years is $18,500.
This is just for the walls.

Granted, there are ways to increase the R value of the stick frame wall, but they all add to the cost, and these increases should be included in any cost comparisons.

Gary

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You can run your own situation on this calculator:
http://www.builditsolar.com/Referenc...sulUpgrade.htm

The stick frame wall R value comes from the NREL whole wall R calculator:
http://www.ornl.gov/sci/roofs+walls/...NS/SimCalc.htm
It accounts for thermal bridging due to studs and framing. Did not include any allowance for this is the strawbale, because it seems like there is little bridging?

Thanks for the comparison link, Gary!

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the Back Gate Country Quilt Shop

I didn't see any reference to strawbale in any of those links. And my form of heating doesn't fit the options either. (Radiant concrete slab heated with water from an electric water heater, and a woodstove.

Hi Snoozy,
The R30 for the strawbales came from an NREL test of strawbale walls. Can't find the actual url right now. Some places quote higher values.

Not sure what you mean when you say your form of heat does not fit the opptions? I don't see why you could not use radiant floor heating for a strawbale home?

Gary

What i meant was I couldn't find "Radiant slab" as an option or factor to tick on the calculator. Of course I can use it. I already do!

The commercial sized straw bale buildings in Pine River MN (HUGS) use 400 lb bales with a 100-R value. I think that for running the electric they placed 4" PVC pipe in the wall for access. If you need to run more wiring you can always pull another wire.

These large buildings are almost entirely heated with solar collectors and storage in the floor using 12" blocks placed on their side to create channels for the heated air.

They have placed sensors throughout the building walls to monitor the moisture content. Our MN summers can be pretty humid.

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