An interesting question came in from the community of Mehlville, just south of St. Louis, the other day. The homeowner wondered if it would be practical and energy-efficient to close off the air register vents in rooms not used very often. Would that practice save on his energy bills?
According to the California Energy Commission, closing vents doesn’t save any energy or money. In fact, it has quite the opposite effect. According to a 2003 study by the Lawrence Berkeley National Laboratory:
“Closing too many registers (more than 60%) is not recommended because the added flow resistance severely restricts the air flow through the system leading to safety concerns…. For example, furnaces may operate on the high-limit switch and cooling systems may suffer from frozen coils.”
The results of this study showed that register closing actually leads to increased energy use for a typical house. It also showed that closing vents can contribute to duct leakage, which actually wastes energy. So this age-old “vent closing technique” is not recommended as an effective energy saving strategy.
At Ricotta Heating & Air, we’ve been asked this questions before and our technicians explain that it makes more sense to set a livable temperature on the thermostat (or program your thermostat according to your peak use and comfort levels) and keep the air circulating throughout the house. For those rooms that are always warmer – consider a whole house fan in the attic, or a portable fan. Both will keep you cooler without damaging your heating or cooling system or significantly raising your energy bill.
— Lew of the Ricotta blog team