7 Signs Your HVAC System Is Wasting Energy—And What to Do About It

As far as your HVAC system (cooling and heating system) goes, what's out of sight is out of mind. But don't always assume your system is running at peak performance. As units age, they become less efficient resulting in increased monthly utility bills. This is no small matter—these incremental changes add up over time, especially considering that keeping a house at a comfortable temperature accounts for about a quarter of the total electricity used in U.S. homes according to the U.S. Energy Information Administration’s Annual Energy Outlook 2017.

Are you concerned that your system isn't as energy efficient as it should be—or could be? Here are seven signs of an underperforming system and what you can do to save on your utility bills.

This post has been brought to you by Mitsubishi Electric. Its facts and opinions are those of BobVila.com.

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  1. 1. The Temperature Fluctuates From Room to Room

    Uneven temperatures signal inefficient hvac

    The design, sizing, and maintenance of the air-handling unit, the indoor unit responsible for moving air throughout the house, and the ductwork attached to distribute conditioned air are critical to achieving comfort indoors. If not properly designed, the occupants can experience hot and cold spots within the space. Likewise, lack of maintenance of the air handler and ductwork can result in dirt build-up and reduced capacity of the system, causing some rooms to achieve the desired temperature while others cannot. Make sure you have routine maintenance to clean the indoor unit and periodic checks to see if ductwork has dirt build-up and needs to be cleaned. Another alternative is zoning, which results in shorter duct runs and improved efficiency.

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  2. 2. The House Remains Humid When the AC Is Running...

    Humidity signals inefficient hvac

    Do you feel clammy indoors even when you're sitting in an air conditioned room? That sticky feeling is a symptom of higher than usual humidity. An efficient HVAC should be able to control both temperature and humidity. As warm air passes over a unit's frigid evaporator coils, the moisture condenses, thereby removing moisture from the air. If, however, an AC unit’s evaporator coils are not cold enough—due to a loss of refrigerant or a maintenance issue—it will not remove as much moisture from the air. As a result, homeowners will often lower the thermostat even more to find some relief, forcing the HVAC to work harder and consume more energy. It is important to ensure the refrigerant charge is correct and the coils are clean to keep the system performing at optimum efficiency.

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  3. 3. ...And It Runs Constantly

    Constant cycling signals inefficient hvac

    Not only does an undersized HVAC system struggle—and fail—to keep your home at a comfortable temperature, the constant struggle to keep up with the desired temperature translates into a substantial waste of energy. Perhaps your system doesn't provide sufficient power for your region's climate, or maybe you added on to your home without updating the HVAC to match the new, larger footprint. Either way, if your system is constantly struggling to keep up with the desired temperature, consult with an HVAC professional at the next system checkup. If the verdict is that your system is oversized or too small for your home's cooling and heating demand (usually referred to as the "load"), think about an upgrade, which can improve your home's comfort and energy usage.

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  4. 4. You're Cooling (or Heating) the Entire House

    Cooling whole house signals inefficient hvac

    Traditionally, older HVAC systems feature a single system, with a single temperature setting, to condition the entire house. A common complaint centers around keeping the temperature set to satisfy one area and other areas experience discomfort from overheating or cooling. Not only does this approach require large amounts of energy to condition the air in every room at once, it does nothing to guarantee individual comfort for everyone in the house. A better approach for comfort and efficiency is to zone the home by living areas. This way, you only condition the space as you use it.

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  5. 5. Utility Bills Have Increased

    Increasing utility bills signal inefficient hvac

    This may seem like a no-brainer, but unless your utility company has increased your gas or electric rates, or you've recently installed another energy-intensive appliance, monthly costs should be fairly consistent year to year. A slight increase in costs is normal with older units, because systems inevitably lose some of their efficiency to normal wear and tear, but big fluctuations are not. Check your billing history. If charges have skyrocketed, that's an obvious indicator that your HVAC system is wasting energy, which can happen when components have to work harder to satisfy demand. Cooling and heating systems will compensate for aging parts by running longer cycles, which results in more energy usage.

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  6. 6. You’re Calling the HVAC Repairman Frequently

    Frequent repairs signal inefficient hvac

    Like all major appliances, HVAC systems benefit from annual tune-ups and require occasional repair. But if you're making an increased number of calls to repairmen to service your air conditioner, furnace, boiler, or any other part of the HVAC system, this could signal that one or more of the units is wearing out. As a component fails, it draws excess energy in an attempt to provide thermal comfort. Once an HVAC system starts requiring frequent major repairs, homeowners should consider replacement.

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  7. 7. Your Current HVAC System Is Approaching 10 Years Old

    Age signals inefficient hvac

    It's important to know how old your home's air conditioning and heating systems are because efficiency is lost over time and more efficient equipment becomes available. Even when using newer systems, which tend to be more efficient, the Environmental Protection Agency’s ENERGY STAR® program recommends replacing air conditioners and heat pump units after 10 years, and furnaces and boiler units after 15. Today's more stringent seasonal energy efficiency ratio (SEER) requirements mean that replacing a 10-year-old HVAC system with a high-efficiency system will translate into immediate savings on operating costs. Consider that a unit installed before 2006 might rate 4 to 10 SEER, but those produced since then range from at least 13 SEER to 26 SEER. The higher the number, the more efficient the system; an older HVAC system nearing the end of its expected life simply can’t compete.

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  8. Upgrading Your HVAC

    Mitsubishi living room interior

    Cooling and heating the home can be expensive, particularly if you're stuck with an old, inefficient HVAC system. For instance, traditional installations with ductwork are notoriously leak-prone, where enough energy is lost in transit to compromise overall system efficiency by up to 30 percent. Moreover, these systems often expel the cooled or heated air on only one side of a room near the registers, which can create drafts and prompt homeowners to fiddle with the thermostat to get comfortable. As you evaluate your HVAC options, you should consider installing a system that corrects or eliminates the problems laid out here.


    A Zoned Comfort Solution™ from Mitsubishi Electric does just that. The system addresses household comfort by zones (be they individual rooms or entire floors), distributing conditioned air directly where it's needed at exactly the desired temperatures. Individual zone controllers help occupants achieve customized comfort while leaving unoccupied rooms alone. Plus, Mitsubishi Electric outdoor units are able to run continuously at variable speeds on very little energy—a huge step up from the disruptive and energy-hungry on-off cycles of traditional systems. Taken together, these upgrades can save the homeowner up to 40 percent on energy bills. For tailored comfort, supreme flexibility, and energy savings, you can’t go wrong with Zoned Comfort Solutions from Mitsubishi Electric.

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