Does Closing Vents in Unused Rooms Save Money and Energy?

 

Energy conservation is a hot topic right now. If your home uses electricity generated in fossil fuel-fired power plants, for every unit of energy actually used in your home, approximately two additional units of energy must be expended in producing and delivering the energy to you. Since heating and cooling together account for about half of the typical home’s total energy use, many people look to these areas to try to reduce their energy consumption (and energy bills).

A common, frequently shared “energy saving tip” is to close vents in rooms you don’t use or use only rarely. The logic behind this seems reasonable: not heating or cooling rooms you aren’t occupying should result in reduced overall energy use. But if your home has a traditional central air, ducted heating and cooling system, closing vents not only doesn’t accomplish this purpose but can cause significant problems.

Ornate heating vent cover and money representing energy loss 

How Your HVAC System Keeps You Warm & Cool

 

Your home’s air blower pulls air from your home through the return ducts, heats or cools it, and returns it to your home through the supply ducts. Blowers maintain proper air flow using sensors that detect pressure differences in the systems. If you have dirty air filters or too many vents are closed, it increases the pressure in your system and makes your motor work harder. This makes it perform less efficiently and can decrease your system-wide air flow. It also increases the amount of air that leaks from your duct system.

In a typical system, closing a vent doesn’t signal the blower to move less air or the air conditioner, heat pump, or furnace to move or produce less heat. The newest technology, zoned duct systems, actually does do this by using variable-speed computerized blowers.

Your air conditioner, heat pump, and/or furnace work by cooling or heating that air that flows past them and circulating it through your home. The returning, room temperature air passes over a coil or heat exchanger and either loses or picks up heat. Most systems are fixed-capacity systems, in which the amount of heat the coil or heat exchanger is capable of absorbing or giving up doesn’t change.

 

Closing Vents Can Lead to Problems

 

If you close vents in your system, the air flow decreases, and less heat is exchanged between the air and the coil or heat exchanger. This adversely affects the performance of your system, regardless of whether you are heating or cooling your home.

Ideally, in summer, a steady flow of hot air flows in over the cooling coil; as the heat is exchanged, the coil warms as the air cools. Reducing the air flow means that the coil stays colder than it should; if you live in a reasonably humid climate, water vapor from the air can condense on the coil and start freezing. Ice on the coil is bad for air flow and makes the compressor work much harder, shortening the life of your compressor dramatically.

In winter, not having enough cool air passing over a heat pump coil can result in a dangerously hot coil, leading to poor performance and potential malfunction. Similarly, low cool air flow in a furnace can allow the heat exchanger to get so hot that it cracks, allowing exhaust gases like carbon monoxide to mix with your heated air. Closing vents in unused rooms in the winter can also lead to condensation and dangerous mold growth.

 

How Can I Save Energy Effectively & Safely?

 

If you have a room that is uncomfortably cool or warm compared to the rest of your home, it’s probably fine to close or partially close a vent or two. If you are spending a significantly large amount on heating and cooling bills, however, closing your vents won't help reduce your costs. You have a number of options that can improve your home energy efficiency, though. Consider improving your attic insulation, adding window wrap, a sliding door, or a storm door, installing a solar fan in your attic, or looking at replacing your roof, windows, or siding  with high efficiency, UV-repellant models to make your home more comfortable and energy efficient.

 

Contact Hedrick Construction today for a free consultation about how you can safely and effectively improve your home’s energy efficiency.

 

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