To control tado° devices using Google Home, you need to add the tado° app to the Google Home app.
To do so, follow these steps in the Google Home app:
Select the plus (+) symbol in the top left corner of the Home screen.
Select Set up a device > Works with Google.
Find and select tado° in the list of Google Home compatible services.
Sign in to your tado° account and accept the conditions.
If you don’t have any Google Home devices, you can connect tado° with Google Assistant. Learn more about this in the Google Assistant Help Center.