This is the 3rd installment of a monthly column from Ben Walker, Co-CEO of Retrotec. Ben's column focuses on observations on the art and science of high-performance building and home testing. 

As many as 30 million U.S. homes may have loose-fill attic insulation made from asbestos-contaminated Zonolite. Here's how to determine if a home has it and what to do if it does.