node-red-contrib-hue-tunable-white

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Node-RED node to automatic change white color temperature of lights as the day progress.

A tiny script to give you a feeling of varying daylight. It's used to increase mental health for people, in this modern world, spending too much time inside.

What is tunable white

Aliases: 'tunable white', 'dynamic white', 'tunable dynamic white', 'kelvin changing'

Its the possibility to change the 'color' of the white light according to the colors of the sun automatically. From the light orange shine in the morning and evening to the blueish light at midday. Basically to simulate daylight even if you don't go outside or during winter when daylight is scares.

Usage

Give the node an input every so often to make it do its thing. E.g. every 15 minutes seams to work good. Also i recommend sending a msg.reset once a day e.g. at night to overrule any manually changed lights back to having its color temperature automated.

To get easy started

In Node-RED editor, click menu at top right corner -> Import -> Examples -> node-red-contrib-hue-tunable-white -> basic.

How it works

At first run all lights are controlled to the right color temperature for the current time. Once this first run is completed the node will do a more careful update of the color temperature. It will only change the color if the lights currently has the default startup color temperature or has the value this node specified last. This means you can still change you lights and this node will respect that you manually took control of the light. If you turn your lights on and off from the mains this is also handled just fine (if you lights startup with its standard value and not the last setting).

Calculating the color

The node will use system time of the server to do a calculation of the color. A caveat to only relying on time is the color does not follow the real state of the sun at your location as I found it more usable to control the light according to a fixed schema.

So this is how its calculated pr default settings: At 7:00 and again at 21:00 the color will be the most orange. At 14:00 the color will be white-blueish.

CT aka Color temperature... or more precise Color temperature represented as a Mired value wiki for Mired. The Mired value is calculated like so: CT(Mired) = 1000000 / CT(Kelvin). So a kelvin color of 2700K is (1000000 / 2700) = CT(Mired) value of 370 on the bridge.

The graph below shows how the color will change according to the current hour.

You can change the setting by defining your own data points in the edit dialog.

Requirements

Requires a Hue Bridge and for you to grab a API key from it: Official guide to getting the API key (aka. username)

Supported devices

Tested with these lights:

• Philips hue white ambiance
• Philips hue color
• Osram LIGHTIFY
• Is ignored: Philips hue white (an only dimable version, no white hue changes)