How to setup automation for the room to maintain specific lumen?

Configuration
1

I have a couple of WiFi light bulbs (14W) which can adjust brightness and colour temp.

Is there a way to set up automation for the room to maintain a specific lumen while considering the brightness already in the room?
What other device do I need?

2

You’ll need something that will report the Lux level. There are a number of devices that will do that for you, most of the Motion sensors that use ZWave do. I’ve also recently bought a mmWave sensor that run’s Zigbee and that has a built in Lux sensor.

You’ll need to experiment to find a good locate for the Lux sensor, or even whether you need more than one in the room.

I’ve been using them for a few years now to adjust the Living Room lights, some days the Automation works perfectly and other days it can run early or late. So you’ll have to factor in some fine tunning to get it just right.

3

In practise, with a bit of trial and error, you might be able to work out at what level to set a dimmable light to compensate for the light level in the room, using a lux sensor as @Maximo has mentioned.

In practise, lux levels yoyo up and down during the day. The amount of light being sensed can vary enormously, even during the day, when for example, a cloud passes over.

I think the best you may be able to do is set some thresholds, like low, medium and high, and then set the lights output accordingly.

Look how much the lux levels can vary:-

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4

Could you please show me how you did the automation?

5

I can explain my automation, which is probably easier for me at least.

Around my house I have a number of devices that provide Lux levels, both inside and out.

Currently I have the below helpers

  • Outside Average (OUTSIDE)
  • Inside Average (INSIDE)
  • Average of Averages (AVERAGE)

When the AVERAGE drops below my chosen threshold my Living Lights are switch on, they switch off if the Average is above my chosen threshold. The lights are only switched on in the afternoon/evening as that’s the time someone is most likely to be in the Living Room. Although over time I would be working on using some form of presence detection.

I also use the AVERAGE for other things around the house, such as Kitchen cabinet lights, garden flood lights, etc.

6

@nart.wdl - do you have a luminance sensor in the room ?

These are often combined with other devices such a a PIR or mmwave motion sensor, but you can buy these separately as well (I think).

Once you have one, simply trigger your automation based on when the devices luminance level changes, which something like this:-

alias: Lounge - Motion Lights On
description: ""
trigger:
  - platform: state
    entity_id:
      - binary_sensor.everything_presence_one_lounge_occupancy
    enabled: true
  - platform: state
    entity_id:
      - sensor.mymotionsensor_illuminance
    id: illuminance
    for:
      hours: 0
      minutes: 0
      seconds: 0
    enabled: true

Then, in the actions section, use a choose condition, and set the bulbs based on what level you want.