Insulation

For now lets forget about the fact that completely sealing your house would be a bad thing. Your house already has so many air leaks that it would really surprise you. Even if your house is brand new you have leaks. Here is what I did to my house when I built it... 

If you always remember this you will be fine. The R in the insulation factor stands for resistance to air flow. Any air flow of course is bad. So by installing insulation you are preventing the movement of air flow.

And then we have the blown in stuff. This is actually old news paper. And taste nasty.