Ventilation 101 is one of those topics that seems simple until you start asking why things are placed where they are—and this conversation covers a lot of ground. It starts with a comparison between standard and high efficiency dryers, and why that extra airflow moving through a high efficiency dryer means more conditioned air getting pulled out of your house (and having to be replaced from somewhere). From there the discussion shifts to bathroom fans—where they should actually be placed for best moisture removal, why the "fart fan" nickname undersells their real job, and how a dirty, overheating fan motor can quietly become a fire hazard. There's also a good breakdown of duct termination mistakes, attic humidity problems, and simple maintenance that most homeowners have never thought to do.