Are Flex Ducts Energy Efficient?

Are flex ducts efficientHeating and cooling accounts for roughly 56% of a home’s energy use, making HVAC the largest energy expense for most homeowners. And your ducts play an important role in this statistic. Are flex ducts, ones that are flexible rather than rigid, the answer to energy efficiency? It depends.

What are flex ducts?

There was once a day when metal ductwork ruled. Everything was firm and rigid. but they still leak air. Metal ducts leak about 10% of the supply air they move and 12% of the return air.

As you can probably imagine, duct leakage is one of the three biggest energy wasters in most homes. So homebuilders began searching for a “better” solution. What they came up with was Flex Ducts. These flexible ducts are not only easier to work with (they are flexible after all), but they tend to leak less air (when installing correctly). But are they energy efficient?

Are flex ducts energy efficient?

ENERGY STAR, LEED for Homes, and the National Association of Home Builders (NAHB) Green Building Standard allow flex ducts. But these ducts are not without fault. Here’s a look at 4 common problems.

  1. These ducts can kink and restrict airflow since they’re flexible. Just think of it as your garden hose. When the hose kinks, water flow decreases drastically. The same goes for flex ducts and airflow.
  2. Flex ducts are often too long. Energy efficiency decreases the longer road conditioned air takes.
  3. Poorly fastened and sealed connections are other issues.
  4. Flex ducts are almost never installed properly.

So, yes flex ducts can be efficient, but they also have A LOT of potential problems. Because of this, metal ductwork is still the way to go. Because they are rigid, they require home builders to properly design and install them. You can’t get away with just throwing some metal ducts in the attic.

Additional benefits of metal ductwork:

  1. Air resistance is lower than flex ducts.
  2. When sealed, metal ducts can be fairly energy efficient.
Duct sealing

During Minnick’s Energy Audit, the technicians will test your ductwork to see if there are any air leaks. Called a duct leakage test, this assessment will determine whether you need to repair or seal your ducts. The test measures the rate of airflow and pressure within the system.

“The ducts need to be tested prior to any sealing to make sure they are properly sized for the required airflow needed for each room,” explains Rob Minnick, CEO/ President at Minnick’s Inc. “Sealing without confirmation of properly sized ducts can do more harm than good.”