Does Closing Off Air Vents Save Energy or Money?

air vent

With the high demand for cooling in the Los Angels area, the old trick of closing air vents to save money gets a lot of attention. Due to the design of the typical home ventilation system, however, this tactic does more harm than good.

Why Closing Vents Doesn’t Help

The idea of closing air registers in unused or rarely used rooms is based on the belief that this reduces the amount of space the heating and cooling system has to cover, so the system will use less energy. It sounds logical. Heating or cooling less space should cost less. In reality, closing vents does nothing to reduce the system’s energy use.

Your home ventilation system was designed with a precise pressure balance meant to distribute air to all your rooms. Closing an air vent increases the pressure in the duct system. If your ducts have any leaks, which many do, the increased pressure forces air out through the leaks. Instead of going into your other rooms, the air goes into your attic, walls, and elsewhere to create humidity and mold problems. To make matters worse, your system has to work even harder to overcome the incorrect air pressure.

It’s safe to close one or two vents, but never close more than 40 percent and only for short periods.

Better Ways to Save

If your home has rooms you rarely use or areas that are harder to keep at a comfortable temperature than others, there are better ways to gain more control. One of these is a zoned heating and cooling system. This system uses a main control panel, programmable thermostats in each zone of the house, and dampers in the ductwork to redirect airflow where you decide it’s needed most. A zone can include one room or several.

Installing a ductless system is another option. These are especially well suited to room additions and finished attics and basements.