Portable air conditioners are similar to window (room) air conditioners. However, instead of being installed in a window, portable ACs are floor-standing units usually outfitted with wheels to allow them to be easily moved. Portable ACs use specialized flex ducts to exhaust the hot condenser air through a window. Portable ACs may be either single-duct units, or dual-duct units, where the additional duct brings in some of the condenser air from outside.
THE POTENTIAL STANDARD:
There are currently no efficiency standards for portable ACs. DOE issued a final rule in 2016, although the rule has not been officially published in the Federal Register. Several organizations filed a lawsuit to compel DOE to publish the rule and are awaiting the outcome. The standards would reduce portable AC energy use by more than 20%.
California, Colorado, Vermont, and Washington adopted the final federal standards as state standards. California standards go into effect on February 1, 2020 and the remainder on February 1, 2022.
Portable ACs draw much or all of the air flow used to reject heat to the outside from the room being cooled. This process creates a negative pressure, which results in infiltration of hot air from outside. Portable ACs also add heat to the room due to heat losses through the duct and the unit’s case. DOE estimates that portable ACs use about twice as much energy as a typical new window AC. The efficiency of portable ACs can be improved by using more efficient compressors and improved heat exchangers.