Automatic circadian lighting - match your lights' color temperature to the sun!

What this does

It gives you cool lights during the day that get gradually warmer around sunset and overnight. The changes are so slow you are unlikely to notice them whilst they are happening. This may even help your circadian rhythm and sleep!

This blueprint updates the color temperature of your lights to match the outside color temperature calculated from the elevation of the sun. See the discussion here on how this calculation came about.
To ensure lights stay in sync it updates lights when they turn on, whenever the sun elevation changes and every 5 minutes.

Requirements

  1. A working sun.sun entity, read the docs. This comes auto-configured on most Home Assistant installations so it is probably there unless you’ve disabled it.
  2. At least one bulb that reports color_temp amongst its attributes.supported_color_modes

Notes

  1. On the bulbs I tested it on (IKEA Tradfri via ZHA) telling the bulb to change color temperature as it turns on would stop it coming on at full brightness, as such a separate action to restore the brightness is called after setting the color temperature. I have exposed this for editing in-case it interferes with any other of your automations, e.g I make my brightness come on low overnight and 100% in the morning.
  2. You have to select every light you want to target - it is monotonous but you will only have to do it once.
  3. Be careful about including light groups. If you do, when you turn on 1 light in the group, every light in the group will be turned on because the automation has to call light.turn_on at the group to change its color temperature - for light fixtures with multiple bulbs this may be a feature, for multiple lights + lamps in a room it will be a bug.
  4. Max and min color temp: There is probably no harm in taking the slider to the extremes. I assume most bulbs will just change to their maximum/minimum if they get a request to change to a color temp that is out of range.
  5. You can see which bulbs support color temp by going to developer tools > states > type "color_temp" into filter attributes. This will probably also show you the max and minimum supported color temp.
  6. If you live at extremes of latitude (e.g Iceland) where the sun elevation never gets very high you may find the the bulbs never get ‘cool’ if this is annoying let me know and maybe we can find a way to normalise the values.

2022.10 or later
Open your Home Assistant instance and show the blueprint import dialog with a specific blueprint pre-filled.

2022.9 or earlier:
Open your Home Assistant instance and show the blueprint import dialog with a specific blueprint pre-filled.

blueprint:
  name: Match Outside Colour Temperature
  description: When a light turns on or the sun elevation changes match the outside colour temperature. It will apply to any bulb that supports color temperature. It triggers whenever a bulb turns on, on sun elevation changes and every 5 minutes.
  domain: automation
  input:
    target_lights:
      name: Lights
      description:  The lights to be controlled
      selector:
          entity:
            domain: light
            multiple: true
    min_color_temp:
      name: Minimum Color Temperature
      description:  The coolest color your bulbs will be set to
      default: 250
      selector:
        color_temp:
            min_mireds: 153
            max_mireds: 500
    max_color_temp:
      name: Maximum Color Temperature
      description:  The warmest color your bulbs will be set to
      default: 454
      selector:
        color_temp:
            min_mireds: 153
            max_mireds: 500
    brightness_action:
      name: Brightness
      description: When a device turns on its color temperature will be set, this may interfere with the brightness, this action will run half a second later to set the light's brightness.
      selector:
        action:
      default:
      - service: light.turn_on
        data:
          brightness: >-
            {{max(trigger.to_state.attributes.brightness,2)}}
        target:
          entity_id: >-
            {{trigger.entity_id}}
        alias: Default - Set light to its original brightness, don't use brightness 1 as it causes issues with some bulbs
variables:
  target_lights: !input target_lights
  target_on_lights: >-
    {{states.light | selectattr('state','eq','on') |
    selectattr('attributes.supported_color_modes','match',".*color_temp.*")
    | map(attribute='entity_id') | select("in",target_lights) | list }}
  min_color_temp: !input min_color_temp
  max_color_temp: !input max_color_temp
  color_temp: >-
    {{ [([((1000000/(4791.67 - 3290.66/(1 + 0.222 *
    ([([0,state_attr('sun.sun',
    'elevation')]|max),90]|min**0.81))))|int),min_color_temp]|max),max_color_temp]|min}}
trigger:
  - platform: state
    entity_id: !input target_lights
    to: "on"
    id: single_light_on
  - platform: state
    entity_id:
      - sun.sun
    attribute: elevation
    id: elevation_change
  - platform: time_pattern
    minutes: "5"
    id: every_5_min
condition:
  - condition: template
    value_template: >-
      {{ (states.light | selectattr('state','eq','on') |
      map(attribute='entity_id') | list)!= [] }}
action:
  - choose:
      - conditions:
          - condition: trigger
            id: single_light_on
        sequence:
          - service: light.turn_on
            data:
              color_temp: "{{color_temp}}"
              transition: 0
            target:
              entity_id: "{{trigger.entity_id}}"
          - delay:
              milliseconds: 500
          - choose:
            default: !input brightness_action
      - conditions:
          - condition: or
            conditions:
              - condition: trigger
                id: every_5_min
              - condition: trigger
                id: elevation_change
        sequence:
          - service: light.turn_on
            data:
              color_temp: "{{color_temp}}"
              transition: 5
            target:
              entity_id: "{{target_on_lights}}"
mode: parallel

Example graph of how the color temperature varies over the day.

image

Change log

2022-10-08 Version 1.1, ensure transition time is 0 for single light turn on
2022-11-23 Version 2.0. Uses Kelvin, link to the old mired version 1.1 is preserved

Help wanted /To Do

3 Likes

I like this blueprint, but now it needs to be updated for kelvin color temp.

Is it broken for you? Still working for me.

It is still changing the color temperature of my lights just fine, but when I go into the automation (not the blueprint) to change the maximum and minimum temperatures the interface is broken. I believe this is because it is using mireds instead of kelvin.

I actually think this is just a UI bug.

However I have made a new kelvin version that works.

1 Like