Air conditioner spec sheets read like alphabet soup. Here's every term worth understanding, and the ones you can safely ignore.
Capacity: kW and BTU
Kilowatts (kW) measure cooling output — the headline number. Australia uses kW; American listings use BTU (British Thermal Units). Divide BTU by roughly 3,400 to convert: 12,000 BTU ≈ 3.5 kW. Rule of thumb: 1 kW cools 8–10 m². Beware listings quoting only input power — a "2,000W air conditioner" might be describing electricity consumed, not cooling delivered.
Efficiency: EER and COP
EER (Energy Efficiency Ratio) is cooling output divided by power input — higher is cheaper to run; portables typically sit between 2.4 and 3.0. COP is the same idea for heating on reverse-cycle units. A COP of 3 means three units of heat per unit of electricity, which is why heat-pump heating embarrasses plug-in heaters.
Reverse cycle
The unit can run its refrigeration cycle in both directions: cooling in summer, heat-pump warmth in winter. Covered fully in types of portable air conditioners.
Refrigerants: R290 and R32
The working gas inside. Modern units use R290 (propane) or R32, both with a fraction of the global-warming potential of the old R410A. Nothing to act on — just prefer the modern gases when comparing, which by 2026 nearly everything sold in Australia does.
Noise: decibels (dB)
Under 55 dB is excellent for a portable; 55–65 dB is typical; above 65 dB will bother light sleepers. The scale is logarithmic — 60 dB is twice as loud as 50 dB — so small differences on paper are big differences at 2am. Look for a dedicated sleep or night mode for bedrooms.
Self-evaporative
The unit flings condensate onto the hot coil and exhausts it as vapour through the duct, so you rarely empty a tank. Standard on good modern units.
Dehumidification rate (L/day)
How much moisture dry mode can extract daily — typically 20–60 litres for portables. Higher matters in humid coastal climates.
Single vs dual hose
One duct out (standard) versus a second intake duct for the compressor (more efficient in big rooms). Explained in the types guide.
The ones to ignore
"Ionizer" and "anion" features add little; "3-in-1"/"4-in-1" just counts modes (cool, fan, dry, heat); and glossy "smart" badging matters less than whether the app actually supports scheduling. Spend your attention on kW, EER and dB — then head to the choosing guide to put it together.