If my calendar says I'm "busy", make the Hue light at my desk "red" -

Connect

This is how I tell my colleagues that I'm not to be disturbed at the moment.

If

Any event starts

This Trigger fires a set number of minutes before the starting time of any event on your Google Calendar. Note: The time in the ingredient will be based on the timezone set in Google Calendar.

Then

Change color

This Action will change the color of your hue lights. NOTE: Accepts color names and CSS hex color values. Defaults to white if no color match is found. NOTE: not compatible with hue lux bulbs.