Older video but the physics haven't changed. 

Learn about the Stack Effect, which is what happens when you look at "hot air rises".  

A house is a box of some shape.  The box has a top and a bottom. If air pushes out of the top because it rises, then air must be put back in to rebalance the loss of air.   This happens at the lowest point, usually the basement.  

https://youtu.be/RLKo1_8SCkI