Let’s examine what “more efficient” means in filter design language. It means the filter will remove smaller particles in larger quantities. Since the average one-inch deep throwaway furnace filter is only designed to remove large particles, it is not very efficient in the language of filter design. However, when it comes to the energy required to move air through the HVAC system, those “inefficient filters” work really well. This is because the larger openings in the inefficient filters require less force to pull air through them.

Using an aftermarket “efficient filter” with the same blower operating inside of the HVAC system means you may end up with less total airflow because it requires more force to get the air through it. Therefore, the only way to regain the correct airflow is to increase the blower’s speed. The faster a blower goes, the more power it takes to operate it. To make things worse, the actual power required to operate your HVAC system grows geometrically when motor speed is increased. This means for even a minimal increase in airflow, the power required increases dramatically, along with the related operating expense.