I’ve heard two theories about using AC or heat when there’s a room in a home not being inhabited. Some people have said keeping the door shut will decrease the useage, where others have said keeping the doorway open will allow the temperature of the home to remain more even steady and an HVAC unit to be more cost-effective. Since I now have two bedrooms in my home that are empty, I decided that it was time to consult a specialist. I am really only using about one third of my home and not in a position to move into a smaller place, but would love to save some money on heating and cooling. I called an HVAC company to inquire about some maintenance on my system and then to ask about some cost saving measures I could put into practice. The HVAC tech checked the indoor and outdoor units, ductwork and the vents. Everything was in fine condition, except my air filter, which needed replacing. He had that particular type with him, and suggested I change mine at the very least every two months, perhaps even more in the cooler and warmer months. When I asked him about the empty rooms, he suggested shutting one off by closing the vent and the door. He said closing off both rooms could cause problems because the air pressure in the ducts remains the same whether it’s utilized or not. Since some of the air is not flowing into the rooms, the excess may result in holes in ducts, the coils to freeze or possibly major damage. The HVAC unit was meant to work for the entire house, so restricting it an excessive amount can cause more damage than the little savings each month would be worth. I followed his recommendation and saw a drop in my monthly utility bill after all.