Yes, insulation is very important. I actually built this house for myself. Took 2.5 years...the insulated concrete forms I used have built in insulation for the

Yes, insulation is very important. I actually built this house for myself. Took 2.5 years...the insulated concrete forms I used have built in insulation for the walls...and for the foundation I used special foam around the edges of the foundation to help with that. A commenter mentioned elsewhere that you would not be able to find contractors to build a house like OP designed - that is a true statement even with my build and that is why I had to build 90 percent of myself (my sons and wife helped too).