lol.. i think you miss the point.. which is why I am here ;-)
We build the main walls in two weeks.. it was great fun. Straw has no thermal mass, so for the rest of your life you will need to chop wood or pay for fuel to heat your house.. The Earthship will heat itself up with its heavy tyre walls.. no bills, no effort for life..

2 weeks of hard work (with a big group is really amazing), traded for a lifetime of comfort!
u can use straw to insulate, but you really need some thermal mass if you want performance!

hope that helps!