Triple glazed aluminum framed windows, with thermal breaks were used as were insulated steel exterior doors. The insulation in the doors could pose a problem if it was directly exposed to the interior of the house, but the steel skin provides an excellent barrier. One of the things that I did that deviates the most from standard residential construction was to use a steel frame. The main reason for this was to avoid the use of toxic termite treatments. After hearing some of the horror stories related to residents being poisoned by these chemicals, I wanted no part of them.
Many builders are familiar with steel drywall studs.
Load bearing studs are readily available also, but they aren't often used because they cost about two and a half as much as wood studs. I have a house under construction with steel studs and a wood roof system. The framing package for this 1200 sq. That is about the cost of treating for termites. I haven't found any insulations that are totally non-toxic, but by having a well sealed house, the insulation can't contaminate the inside air.