New Delhi, Jan. 6 -- Is it better to unplug appliances during vacation? This question usually shows up halfway through packing when the bags are almost zipped and the house is quiet. You're doing that last slow walk-through, switching off lights you already switched off once. Then you stop near the socket, the TV screen is black but the standby light is still on. The microwave clock glows faintly. The router blinks away like it always does. You pause longer than you expect to, wondering - do you actually need to unplug everything, or is this just one of those habits passed down because it felt responsible?

For most people, the worry isn't the electricity bill. Standby power use is tiny, especially over a week or two. That's not what make...