The answer to the question of which attic insulation is best is, of course, entirely circumstantial. When the design of your attic allows, the best attic insulation is inexpensive, easy to install and will yield the performance you're looking for.
Daniel Roy is one of the owners of a recently completed Passivhaus in Falmouth, Massachusetts. Designed by architect Steve Baczek, the house was featured in a series of FHB articles and videos. In this post, Dan shares his experience from the first year in a new super efficient house.