The Stack Effect is the driving force behind how air moves through your home. As conditioned air escapes out of the top of your home through the attic, outside, unconditioned air is pulled in at the bottom of your home through the basement or crawl space. All homes leak at different rates, the tighter the building envelope of your home is, the slower air will leak out of your home and the longer you will keep the air you paid to heat and cool. Leaky homes result in high energy bills, uncomfortable rooms, poor indoor air quality, and wear and tear on your HVAC unit.