One has to look at the complete cost of something they are putting into their house before making a decision. The cost of insulation is small compared to the ongoing heating and cooling costs once it’s installed. After several decades of use, spray foam insulation has proven time and again that the energy required to heat and cool a home drops considerably compared to fiberglass (typically 30%). This savings continues throughout the entire life of the building. Spray foam is also considerably more comfortable. Fiberglass is a mistake that cannot be undone in most cases.