Ah, yes, we run into your brother-in-law quite often. Incredibly, not only is he a bathroom fan expert, he also has the ability to foresee stock market trends, diagnose car engine noises, solve international diplomatic crises, and coach most professional sports teams. Even with his profound knowledge base, however, we would still recommend having the building science experts at E3 install your ventilation systems. There’s a lot more to it than one might think.