Photo by Toa Heftiba / Unsplash

Managing Natural Light with Home Assistant

Home Assistant Nov 6, 2023

In the realm of smart home automation, managing natural light effectively can not only enhance the comfort of your living space but also contribute to energy efficiency. Today, we're delving into a Home Assistant automation that exemplifies this principle by controlling roller blinds based on ambient light levels.

This is very helpful, for example, when you're sitting in front of the TV and the sun is blinding and you can't see much anymore. This can be especially helpful when gaming.

The Automation: "Rollos schließen wenn zu hell"

Translated from German, "Rollos schließen wenn zu hell" means "Blinds close when too bright." This automation is designed to adjust the roller blinds in response to the intensity of sunlight entering the room. Let's break down how this automation works in detail.

The Trigger

The heart of any automation is the trigger—the event that sets the automation into motion. In this case, the triggers are based on the illuminance levels detected by light sensors, specifically the Mi Light Detection Sensor. There are four triggers in total, two for the living room ("wohnzimmer") and two for the kitchen ("küche").

  1. Living Room Blinds Close (wohnzimmerRollosOn): When the illuminance level rises above 10,000 lux, indicating a very bright condition, the living room blinds will be triggered to close.
  2. Living Room Blinds Open (wohnzimmerRollosOff): Conversely, if the illuminance drops below 8,500 lux and stays there for at least 20 minutes, it signals that the room has become sufficiently dark to warrant opening the blinds.
  3. Kitchen Blinds Close (kucheRollosOn): Similarly, the kitchen blinds will close when the light level exceeds 10,000 lux.
  4. Kitchen Blinds Open (kucheRollosOff): And they will open again if the light level falls below 8,500 lux for a continuous 20-minute period.

The Action

Once a trigger condition is met, the automation proceeds to the action phase. This is where the Home Assistant instructs the roller blinds to either open or close.

  • Closing the Blinds: When the "close" trigger is activated, the Home Assistant sends a command to the roller blinds, which could be either the Aqara Roller Shade Driver E1 or the IKEA Kadrilj Roller Blind, to close and block out excessive sunlight.
  • Opening the Blinds: If the "open" trigger condition is fulfilled, the blinds are instructed to open, allowing natural light to fill the room.

The Devices

This automation utilizes a combination of smart home devices to achieve its goal:

  • Aqara Roller Shade Driver E1: This device is a smart motor that can open or close roller blinds automatically. It's compatible with various blinds and can be controlled wirelessly.
  • IKEA Kadrilj Roller Blind: A smart roller blind that can be adjusted to different heights and can be integrated into the Home Assistant ecosystem for automated control.
  • Mi Light Detection Sensor: This sensor measures the light intensity in lux and communicates with the Home Assistant to trigger the automation based on predefined thresholds.

Practical Benefits

This automation offers several practical benefits:

  • Comfort: It maintains optimal light levels in your home, ensuring that it's never too bright or too dark.
  • Energy Efficiency: By controlling the amount of sunlight entering the room, it can help in reducing the need for artificial lighting and even heating or cooling expenses.
  • Protection: It protects your interior from the harmful effects of UV rays and excessive sunlight exposure.


The "Rollos schließen wenn zu hell" automation is a prime example of how smart home technology can be harnessed to enhance living conditions. By automating mundane tasks such as adjusting blinds in response to changing daylight conditions, Home Assistant not only adds convenience to our lives but also helps in creating energy-efficient and comfortable living spaces.

As always you can find the automation on GitHub along with all my other automations.

homeassistant-config/automations.yaml at 155eab0417810e97635fd8a3efe8e45409ef0062 · fwartner/homeassistant-config
My personal home assistant configuation files. Contribute to fwartner/homeassistant-config development by creating an account on GitHub.