predicted future wars
A tighter built home means less outside air infiltrating in the home, which in turn means less oxygen to use for combustion within the furnace. As the furnace burns fuel and oxygen for combustion, it "eats up" the nearby air, which has to be "made up" with fresh air. If air cannot type in the home as quickly anymore, this could cause serious issues. As the surrounding air can be used for combustion, and not substituted for fresh air, a bad pressure in the space can take place. This could create combustion trouble for the furnace, plus consume fresh air for any person inside home.