Ducted HVAC vs. Mini-Splits: Which Is Better? – GreenBuildingAdvisor

Q&A Spotlight

An owner-designer weighs the advantages of central ductwork and individual minisplits for a small, high-performance home

Unless you live near or south of the equator, heating season has arrived. Choosing a heating and cooling system for a new home can be complicated, particularly when the house is small and energy-efficient. A central ducted system can provide even temperatures, good air filtration, and whole-house humidity control. But individual ductless minisplit heat pumps offer some advantages, including room-by-room temperature control, installation flexibility, and the ability to operate only where heating or cooling is needed.

Allison Bailes recently made the case for single-zone minisplit heat pumps, comparing them with multisplit systems that connect several indoor units to one outdoor unit. We covered a similar question in an earlier Q&A Spotlight.

Central ducted systems have their own advantages. The equipment is generally less visible, and ductwork makes it easier to incorporate centralized filtration and humidity control. However, ductwork takes up space, adds to installation costs, and can introduce efficiency losses if poorly designed or installed.

In a recent GBA discussion, member “big_o” (we’ll call him Big) questioned whether a ducted system makes sense for the house he’s designing in North Texas (Climate Zone 3A). The two-bedroom, 1,200-sq.-ft. house will also have an 800-sq.-ft. conditioned attic. Big estimates the heating load at approximately 21,000 Btu/hr.

His original plan calls for four single-zone minisplit heat pumps: one for each bedroom, one for the living room, and one for the attic. But when he presented the idea to an online group, the response was unanimously in favor of a central ducted system.

“I’ve thought about it a lot, and a ducted system makes even less sense,” Big writes. He estimates that four 9,000-Btu/h single-zone minisplits could be purchased and installed for approximately $500 each.

Questioning the advantage of ductwork

Big outlined eight commonly cited advantages…