New Delhi, April 27 -- The ceiling fan has been running on full blast since March. You've already tried blackout curtains, a cold shower at midnight, and convincing yourself that "it's not that bad." It is that bad. And so, here you are, finally ready to buy an AC. But the moment you open a browser or walk into an electronics store, a new problem presents itself: which kind? The chunky window unit your parents relied on through decades of scorching summers, or the sleek split AC that every new apartment seems to have mounted on its walls?

This isn't a small decision. The AC you buy today will sit in your room for the next 8-12 years, show up on every electricity bill, and either let you sleep peacefully or keep you up with its hum. Getti...