Single-hose portable ACs waste energy — a second hose
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- Single-hose portable air conditioners blow room air out through the exhaust hose, which continuously draws hot outside air in through windows or gaps elsewhere in the home, forcing the unit to work much harder — especially as outdoor temperatures rise above 28°C
- European efficiency labels based on British thermal units and the seasonal energy efficiency ratio (SEER) do not account for hot air infiltration, allowing single-hose units to earn misleading "A" ratings despite the real-world design flaw
- The US has introduced two better metrics — seasonally adjusted cooling capacity (SACC) and combined energy efficiency ratio (CEER) — that reflect the energy penalty of pulling in hot outside air, with SACC typically running a third lower than unadjusted capacity figures
- GE sells a conversion kit for some of its single-hose models that adds a second hose, advertising a threefold increase in cooling power; DIY converters using tape, cardboard, or 3D-printed parts report similarly dramatic improvements, which the author confirmed during the May 2025 UK heatwave
- Chris Michael of Meaco said consumers find dealing with two ducts difficult and often lack the space to vent both, explaining why single-hose units dominate UK sales; Meaco is considering launching a dual-hose-convertible portable air conditioner in 2027
- The UK Department for Energy Security and Net Zero and the Energy Saving Trust did not respond to the author's requests for comment on regulating portable air conditioner sales or labelling
Why it matters: With heatwaves driving a surge in portable air conditioner purchases, millions of consumers are paying far more in electricity than labels suggest while emitting more carbon per unit of cooling — and the fix (a second hose) costs a fraction of a new machine. The regulatory gap means buyers cannot tell which units waste energy until they run them, and neither the UK nor the EU has signalled it will close it.
