Steel SIPs might be worth considering.
I have had very good experiences with Steel Structural Insulated Panels. Very strong, affordable, durable, fire resistant and extremely well insulated. Only downside so far is that they transmit sound if left bare. I suppose my current shop could be considered a barndo of sorts (looks like a warehouse on the outside). It has living quarters (loft) in which I have never had issues with smells etc.
