Shutting a room to save energy sounds like a sensible home efficiency strategy. In fact, every year at this time homeowners close off unoccupied rooms for the winter, shutting the supply vent that delivers heated air and closing the door. When rooms were individually heated by a fireplace or woodstove, isolating unheated rooms made sense. However, with today’s central forced-air furnaces dispersing heated air through ductwork, shutting a room to save energy actually often has the opposite effect.
Forced-air systems rely on consistent air balance throughout the home. This means the volume of heated air entering a room through supply ducts is equaled by the volume of air taken out through return ducts. Let’s look at what happens when that delicate balance is tipped:
- When the furnace supply register is closed in one room, air continues to be drawn out of the room. Air pressure in the room shifts to negative. A depressurized room sucks in cold outdoor air through the myriad structural cracks and gaps that exist in any home, and temperature in that room declines abnormally. The acute coldness draws heat energy from adjoining rooms through walls and ceiling, affecting overall temperature in living spaces. Your furnace works overtime to offset the heat loss and heating costs go up, not down.
- All residential ductwork leaks some conditioned air, even under normal static duct pressure. However, when one or more supply outlets are closed and the blower output remains the same, static pressure in the ducts increases. This forces a higher percentage of heated air out of existing ductwork leaks and into unconditioned spaces like the attic or the crawl space. Your furnace has to run extended “on” cycles to make up for this lost heat and reach thermostat settings, wasting energy and boosting utility bills.
For more than 50 years, Amarillo Air Conditioning has served homeowners in the community with year-round heating and cooling expertise. Before shutting a room to save energy this winter, let us suggest more effective options to get the job done.
Our goal is to help educate our customers in Amarillo, Texas about energy and home comfort issues (specific to HVAC systems). For more information about energy savings and other HVAC topics, download our free Home Comfort Resource guide.
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