Why The Ductwork In Your Attic Has An Effect On Energy Efficiency

The ductwork in your attic has a direct effect on your home’s energy efficiency. According to the laws of thermodynamics, hot air has more energy than cold air, which means warm air moves toward cooler areas. If your attic ducts are not properly sealed or insulated, warmed air moving through the ducts will escape into the cold attic, either through the leaks or conduction. Similarly, during the cooling season, hot air that collects in the attic will warm the cool, conditioned air in the attic ducts, also wasting energy. Wasted energy from leaky and uninsulated attic ducts can cost homeowners hundreds of dollars on their annual utility bills.Attic ductwork should be properly installed, sealed and adequately

Design/installation. If you have an older home (built prior to 1980), there’s a good chance the ductwork needs to be upgraded. A professional ductwork design will include a mechanical plan that’s tailored to your home. Things to consider:

  • BTU heat gain and loss for each room.
  • Parallel ducts versus one main line – parallel ducts are more efficient.
  • How much of the ductwork runs through unconditioned areas such as your attic or crawlspace.

Sealing. There are two reasons sealing ductwork is so important: conditioned air will be forced into unconditioned spaces, and unconditioned air can be pulled into the ductwork. This affects the temperature balance in your home and can also diminish indoor air quality, allowing dust, mold spores and other debris in. There are several options for sealing leaky ducts:

  • Tear off the insulation, inspect and repair any leaks, and re-wrap ducts with a radiant barrier blanket/insulation.
  • Use mastic sealant or metal tape to close up any leaks. Don’t use common duct tape; it won’t last.
  • Replace metal ducts with flex ducts, although metal ducts that are repaired and sealed work best.
  • Add one to two inches of closed cell spray foam on the ducts (make sure this meets your local building code standards).

Insulation. The last component of energy-efficient ductwork is insulation. Talk to a contractor about the best insulation to use for this application. Depending on the clearance around walls and fixtures, the highest R-Value may not be practical. Here are recommended R-Values for Zone 4, which includes our area.

If you suspect the ductwork in your attic needs attention, please contact us at Overland Park Heating & Cooling, Inc. We have been helping Kansas City area residents improve their energy efficiency since 1983.

Our goal is to help educate our customers in Overland Park, Kansas about energy and home comfort issues (specific to HVAC systems). 

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