Guides
Reading the energy label on an air conditioner
The rating expresses cooling delivered per unit of electricity consumed. A higher figure means the same cooling for less power, and across a long twin-cities summer that difference is substantial. Compare ratings only between units of the same tonnage — a bigger unit will always consume more.
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What the number is actually measuring
Efficiency ratings express cooling output against electrical input. Higher is better, and the difference between the bottom and top of the range on the same tonnage is meaningful over a season of daily running. It is the single most useful number on the box for anyone who will run the unit regularly.
Compare like for like, or the number misleads
A 2 ton unit with an excellent rating still consumes more than a 1.5 ton unit with a mediocre one, because it is doing more work. Ratings compare efficiency, not consumption. Size the unit first using the tonnage calculation, then compare ratings among units of that size — in that order, or the comparison is meaningless.
Test conditions against a Rawalpindi June
Ratings are measured under standard conditions that are milder than a peak afternoon here. Every unit performs below its label when the outdoor temperature is extreme, and units differ in how gracefully they degrade. Treat the rating as a reliable way to rank units against each other rather than a promise of absolute performance in July.
Where the rating stops being the deciding factor
For a guest room used a few weeks a year, the efficiency premium has too few running hours to pay back and the purchase price matters more. For a bedroom running nightly for five months, the rating is the number to optimise. Running hours decide how much weight to give it.
What do AC star ratings and EER mean?
Is a higher-rated AC always worth the extra?
For daily use through a long summer, generally yes — the running-cost saving compounds across the season and the payback lands within a few years at current tariffs. For occasional use it does not, because there are too few hours for the saving to accumulate. Match the spend to the hours.
Do inverter units always rate better?
They generally do, because modulating instead of cycling is inherently more efficient at part load, and that is where an AC spends most of its life. But there is spread within both categories, so compare the actual figures on the units in front of you rather than assuming the label follows the technology.
Will the unit actually deliver its rated cooling in peak summer?
Not fully — every unit derates as the outdoor temperature climbs above the conditions the rating was measured at, and our peak afternoons are well above them. That is one more reason not to size right at the boundary: a unit that is exactly adequate on paper will feel short in the week you needed it most.