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.
DOE issued a final rule at the end of 2016 establishing the first national standards for portable ACs. However, DOE delayed final publication for three years until compelled to publish by the courts. The standards were finally published in the Federal Register on January 10, 2020 and will take effect on January 10, 2025. The standards will reduce portable AC energy use by more than 20%.
California, Colorado, Vermont, and Washington adopted the final national standards as state standards in 2018 and 2019. The California standards took effect on February 1, 2020, and the remainder will take effect on February 1, 2022. States that adopted the standards prior to publication of the national standards can implement the standards until the 2025 federal compliance date.
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.