hardware//standby power

Standby power is the electrical power a device draws while switched on but doing no useful work, or while nominally off. It matters for anything left running permanently (a router, a home server, a laptop kept reachable), because a small draw over the 8,760 hours of a year becomes a measurable amount of energy.

Standby power is the electrical power a device draws while switched on but doing no useful work, or while nominally off. It matters for anything left running permanently (a router, a home server, a laptop kept reachable), because a small draw over the 8,760 hours of a year becomes a measurable amount of energy.

The arithmetic is the whole tool. Energy is power times time, so a constant 1 W for a year is 8.76 kWh; at a price of 0.15 € per kWh that is about 1.30 € a year per watt. A laptop idling at 5 W with its screen off costs around 6.5 € a year; the same laptop with its screen on and a stuck process holding a processor core can draw five times as much.

The idle draw of a computer is set less by the machine than by what it is left doing. The display is usually the largest single consumer at rest, and one background process spinning in a loop keeps a core out of its low-power states; finding those two is most of the saving.

Network services that wait for packets cost almost nothing while waiting. A process blocked on a socket uses no processor time, and a WireGuard tunnel with no traffic sends nothing, so making a machine reachable adds little beyond keeping it awake.

Sleep is where the real saving lies and also what breaks reachability: a sleeping machine draws a watt or less but answers nothing. A machine meant to be reached at any time pays for staying awake, and the useful work is making that waking state as quiet as possible.

Measuring beats estimating. A plug-in power meter reads the draw directly; a laptop can measure itself by running on its battery for a timed interval (lithium-ion battery).