Question: building materials that are eco friendly?
Answer: Recycled Steel. Producing and smelting steel takes a lot of energy. ...  Bamboo. Bamboo is increasing in popularity as a building material. ...  Sheep's Wool. Sheep's wool, of course, can also be regrown quickly. ...  Straw Bales. ...  Precast Concrete. ...  Earth. ...  Plant-Based Polyurethane Rigid Foam.