Our house has forced air heating and cooling. The most annoying parts of it are dust and spreading of odors. You could just be finished dusting in our house and see a fine layer of it on furniture just a few hours later. Plus, if I was cooking something with garlic or onions, you could smell it all throughout the house when the heat or AC was on. We have a good stove vent, but our filter system in the furnace and AC was not the best. I called a place that upgrades HVAC in New York City after my neighbor told me about the HEPA and electrostatic filtration system he has. It is like those room air purifiers, but it works throughout the whole house.