Air Cooler vs Air Conditioner — An Honest Comparison

An air conditioner is a heat pump. It moves heat from inside the room to outside, and in doing so it condenses moisture out of the indoor air. The room gets cooler and drier, and because it is a closed loop it works regardless of the weather outside.

An air cooler is an evaporative device. Air is drawn through wet pads, water evaporates into it, and the energy for that evaporation comes out of the air as heat. The room gets cooler and more humid. Because the effect depends on the air's capacity to absorb water vapour, it weakens as humidity rises — and stops almost entirely in muggy weather.

Every practical difference below follows from that one distinction.

The gap is real and large, but it is a factor of about six, not the order of magnitude some marketing implies. And it assumes the cooler is actually doing the job — a cooler running in humid air consumes its 190 W and delivers very little, which makes it infinitely expensive rather than cheap.

• Dry heat (Delhi, Jaipur, Ahmedabad, Nagpur, Hyderabad, April-June): the cooler delivers most of the comfort for a fraction of the cost. Genuinely the better buy for many households.
• Humid heat (Mumbai, Chennai, Kochi, Kolkata, coastal Gujarat; anywhere in the monsoon): the AC is the only one that works. A cooler adds moisture to air that already has too much.
• Rented homes: the cooler needs no installation, no wall penetration and no permission, and it moves with you.
• Sealed or internal rooms: the AC, because the cooler needs a ventilation path it does not have.
• Very large spaces — factories, warehouses, halls: industrial coolers, almost always. Air-conditioning that volume is prohibitively expensive, and the ventilation a cooler needs is usually already there.
• Asthma and allergy: neither is a treatment. A cooler raises humidity, which can encourage dust mites and mould if it is not maintained; an AC's filter is not an air purifier.

In much of India the summer is dry before the monsoon and humid after it. A common, sensible arrangement is a cooler for the dry months and a fan — or an AC in one room only — for the humid ones. That is not indecision; it is matching the device to the weather it works in.

If you do own both, running a ceiling fan alongside an AC lets you set the AC two degrees higher, which usually saves more than the fan costs to run.