5 Home Assistant Automations That Save Energy

Thu, 20 Aug 2026 00:00:00 +0000

My router, speakers, AV receiver, and printer used to draw a combined 76 watts while doing nothing. If they ran around the clock, that would cost almost €180 per year at my electricity rate. This is where automations help me: not through one spectacular trick, but by preventing small amounts of wasted energy every day.

Here are five solutions from my actual home. Four reliably reduce my energy costs. The fifth sounded sensible but provided no benefit with my heat pump, so I removed it again.

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1. Automatically switch off standby power hogs

My home currently draws around 55 watts of base load when idle. This includes devices that need to remain reachable for the smart home, such as Shelly modules, sensors, and my home server. I consciously accept that consumption.

Several other devices, however, used to stay on even when nobody needed them:

Device	Power	Annual cost if always on
FRITZ!Box router	16 W	almost €40
Five Sonos speakers	35 W	over €80
AV receiver	15 W	around €35
Printer	10 W	around €24

Together, these examples add up to 76 watts. My actual savings are lower than the theoretical €180 because I do not keep the devices off permanently. Home Assistant simply makes sure they are off whenever I do not need them.

When I leave the apartment, I long-press the hallway light switch. This deliberate “I’m leaving” signal switches off Sonos, the receiver, and the printer. The manual trigger is intentional: for this use case, I prefer an unambiguous button press over presence detection that occasionally gets it wrong.

I also switch off the FRITZ!Box at night. My smart home continues to run locally without internet access. I explain why local operation matters in Home Assistant A–Z: O for Offline.

There is a small downside: the Sonos speakers need about a minute after power-up, while the router takes roughly two minutes before everything is available again.

2. Run large loads on solar power

If you have solar panels, flexible high-power appliances should run whenever enough of your own electricity is available. In my home, this mainly applies to the washing machine and electric car.

My washing machine is connected to Home Assistant through Home Connect. In the morning, I load it, select a program, and enable remote start. Once around 2.5 kilowatts of surplus solar power are available, Home Assistant starts the machine automatically.

The car follows the same principle. My Heidelberg Energy Control wallbox is connected to the solar system through Home Assistant and evcc. The Cupra Tavascan charges primarily on surplus solar power unless a defined minimum state of charge takes priority. Of the roughly 3,500 kilowatt-hours the car uses each year, about 1,500 kilowatt-hours come from my own roof despite my relatively small solar array.

3. Get reminded to ventilate efficiently

Leaving a window open for too long wastes heating energy in winter. With a heat pump, that directly becomes additional electricity consumption. I therefore monitor the windows I regularly open using six Homematic contact sensors. The outdoor temperature comes from my heat pump sensor via Modbus.

My simple rule, deliberately tailored to my home, is:

Below 5 °C: send a reminder after 5 minutes
Between 5 and 15 °C: use the temperature as the number of minutes
Above 15 °C: do not send a reminder

If a window remains open beyond that limit, the Home Assistant app sends a push notification. This prevents forgotten windows without creating unnecessary alerts during mild weather. These values are not a universal ventilation formula; they are thresholds that work well for my building.

Bonus: Automate the electricity price too

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Automations can reduce consumption or shift it to times when your own solar power is available. Another factor is the price per kilowatt-hour. During my most recent provider switch, I saved 5 cents per kilowatt-hour and received an additional €250 switching bonus.

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4. Why I removed night setback

Turning down the heating at night sounds like an obvious way to save energy. Whether it works depends on the building, heat emitters, heat source, and control system.

In a poorly insulated older building with conventional radiators, night setback can indeed save energy. With my combination of a heat pump, underfloor heating, and a high-mass screed floor, however, the room temperature barely drops overnight. If the controller then catches up in the morning using a higher flow temperature, that less efficient operation can consume the small theoretical saving.

Night setback provided no measurable benefit in my setup, so I removed the automation. The better rule is not to apply it blindly, but to compare actual consumption over equivalent periods.

5. Shutters save energy in summer and winter

My shutters close automatically based on the position of the sun. This saves energy in two ways:

In summer, they keep solar heat outside, reducing the work required from an air conditioner.
In winter, closed shutters add another layer in front of the windows at night, reducing heat loss and the amount of electricity required by the heat pump.

I explain how to create sun-dependent shading with Home Assistant blueprints in Home Assistant A–Z: J for Shutters.

Conclusion

None of these automations is a revolution on its own. Together, however, they prevent unnecessary standby consumption, make better use of solar power, and reduce wasted heating or cooling energy. Once configured, most of them run almost entirely by themselves.

Night setback is the important counterexample: an automation does not automatically save energy just because it is commonly presented as an energy-saving tip. What matters is what it actually does in your home.

Which smart home automation saves the most energy for you – and which supposed energy-saving trick did you switch off again?

Shutters on Smart Home? Sure — But Secure!

5 Home Assistant Automations That Save Energy

1. Automatically switch off standby power hogs

2. Run large loads on solar power

3. Get reminded to ventilate efficiently

Bonus: Automate the electricity price too

4. Why I removed night setback

5. Shutters save energy in summer and winter

Conclusion