Last updated 8 September 2026
This policy covers a personal, single-user Home Assistant installation that uses Google's Smart Device Management (SDM) API and Cloud Pub/Sub to communicate with the owner's own Nest thermostat.
The owner of the installation, and no one else. The application is not distributed, and no other person can sign in to it or use it.
With the owner's authorisation, the application reads thermostat state — current
temperature, humidity, target setpoint, and whether heating, cooling or the fan is
running — and may change the setpoint or mode. It uses the
sdm.service and pubsub scopes solely for this purpose.
Thermostat readings are stored on hardware in the owner's home and are used to analyse heating and cooling energy use. The data is not sold, shared, transmitted to third parties, or used for advertising, analytics, or profiling. No data is transferred to any other person or organisation.
Readings are retained locally for as long as they remain useful for energy analysis, and can be deleted by the owner at any time.
Access can be withdrawn at any time from the Google Account permissions page at myaccount.google.com/permissions, which immediately ends the application's ability to read or control the thermostat.