Smart plugs and scheduling for cooling

Automation gets sold as free savings. It is not free, and the certified data lets us say exactly what it costs.

The certified ceiling fan dataset records standby power separately from running power, and it flags which models have connected functionality. Across 1,398 certified fans:

• 53 have connected functionality — 3.8% of the field. It is a niche, not the default.
• Connected fans average 1.74 W standby.
• Everything else averages 0.90 W.

Roughly double, and unlike running power, standby is drawn all 8,760 hours of the year. At 18.34¢/kWh the difference is about $1.35 a year per fan.

That is a small number, and stating it plainly is the point: the standby penalty is real and it is not large. What it does not justify is paying an efficiency penalty on top. The best connected fan here manages 0.8 W, below the non-connected average — so the penalty is avoidable if you check the number.

This is the one hard rule on the page, and it is a hardware constraint rather than a preference.

• Compressors must not be restarted immediately. After shutdown, refrigerant pressures need time to equalise. Restarting against high head pressure stresses the compressor, and short-cycling is a recognized cause of failure.
• A smart plug cuts power without knowing any of that. The unit’s own controls enforce a minimum off-time. A plug simply removes the supply.
• Many units do not resume after a power cut. They come back off, or in a default mode, so the schedule silently does nothing.
• Startup current is high. Compressor inrush is well above running current, and plug ratings are not always sized for it.
• Most manufacturers prohibit it. Manuals commonly require a dedicated outlet and forbid extension cords, plug adapters and timers.

Use the timer built into the unit. Every certified model has one, it understands the compressor’s state, and it does not void anything.

1. Pre-cooling. The largest real saving available from automation, because cooling made in the cooler hours costs less per unit — the timing case in full. Do it with the unit’s own timer.
2. Overnight window fans. A thermostat-controlled window fan works the indoor/outdoor crossover for you while you sleep. Fans are safe to switch at the socket.
3. Turning things off. The most reliable saving in automation is not running something you forgot about — and a fan running in an empty room is the classic case.
4. Time-of-use tariffs. If your rate varies by hour, a schedule that avoids peak hours is worth more than any efficiency difference between two units.

And one place it does not pay: an empty room. Automation that cools a space nobody enters is the scope mistake with a schedule attached.

• Check the standby figure before buying connected. It ranges from 0.5 W to 2.0 W across the certified connected fans, which is a fourfold spread for the same feature.
• Prefer built-in control to a plug. A plug can only cut power; built-in control can set a speed.
• Check what the device does after a power cut. A fan that comes back off makes the schedule useless.
• Do not automate a pet’s room with fans. A fan switching on unexpectedly in an empty room startles animals — why that matters.
• Nothing here beats shading. Load reduction has no standby draw at all.