Does Closing the Vents in a Room Save Energy?

Talking to an HVAC Professional

An HVAC professional may determine that closing vents in an attempt to save energy is counterproductive and can actually cost you money by making it necessary to use more energy. If a heat vent is closed, suction from the air duct return may pull cold air in from the outdoors through cracks around windows, doors and electrical boxes in exterior walls. The HVAC expert will also check the heat duct seams to make sure they are sealed properly. If not, the extra pressure from the vents that were closed can force hot air in through leaks. An HVAC professional will also determine if closing vents will cause damage to your heating or air-conditioning systems.

It sometimes makes sense to close forced-air heating vents to save energy. However, the vents in question must meet certain conditions. First of all, they must not be located in a room essential to keeping water pipes from freezing. Rooms with water pipes located in the walls or under cabinets may need sufficient heat to keep pipes at the proper temperature. Also, there must be a cold-air return in the room you are considering closing off. And, of course, make sure the thermostat controlling the furnace is not located in that room.

Closing vents may cause damage to high-efficiency forced-air furnace systems. These heating systems are set to run the fan at different maximum speeds, and if you shut off some vents, you may get a lot of air pushing through a reduced number of vents. It may be possible to reduce the speed of the fan at these vents. You can also look into purchasing a programmable thermostat that opens the vents at certain times of the day. This device also works for air conditioning.

A study conducted by the Ernest Orlando Lawrence Berkeley National Laboratory concluded that vent closing actually led to increased energy use. The study was conducted in California for a typical home over various combinations of climate, duct leakage and number of closed vents. The practice of closing vents to save energy was not recommended in most cases.