Variable-Speed HVAC Is Worth a Second Look
Ductless variable-speed HVAC systems offer impressive energy savings, so why haven't they caught on in the U.S.?
Author: By Dean Gamble
Over the last 20 years, the Energy Star Certified Homes program has worked with builders to construct more than 1.6 million energy-efficient homes. Tried-and-true strategies like air sealing and increased insulation form the core of our program, but we’re always looking for emerging technologies that will raise the bar on efficiency.
One of those technologies has actually been around for decades, but only recently has begun popping up in the United States. Ductless variable-speed HVAC systems may not sound very exciting, but wait until you learn more.
Almost all heating and cooling systems used in U.S. homes have just two modes--on and off. During a hot summer day, your air conditioner will probably be on a lot more than it’s off. And during a more temperate spring day, it will be off more than it’s on. But in both examples, it’s just cycling between these two modes--on and off.
How is a variable-speed HVAC system different? As the name implies, it has many different modes. You can think of this a little bit like the features in your car. In your car, you can set the fan to low, medium, or high. And you can set the temperature to very cold or just slightly cold. Variable-speed cooling systems for your home offer similar features, controlled automatically by your thermostat. This can save energy and keep you more comfortable, both by producing just the right amount of cooling and heating and by better managing humidity.
These features alone make variable-speed systems stand out and worth a look by builders. But many are paired with another important feature--no ducts. Instead of ducts, the heated or cooled refrigerant is distributed to different zones within the home, where a small fan in each zone heats or cools just that space. This allows comfort to be tailored to each zone. It can also increase savings by eliminating ducts in unconditioned spaces and only conditioning the zones desired by the homeowner.
Between the advanced controls, variable settings, and lack of ducts, these systems can produce impressive energy savings. With all these features, you can also imagine why ductless variable-speed HVAC systems have become so popular around the world. But why has the use of this technology been limited in the U.S.? There are several reasons: higher equipment costs; limited distribution; lack of familiarity; and for the ductless versions, aesthetics. Regardless, this technology has started to gain traction in areas that play on its strengths. That should lower the remaining hurdles, making this a promising emerging technology.
This article was originally published by Builder on January 6, 2016.