We wanted to be able to control temperature in response to a person's activity. Instead of manually changing temperature (e.g. using the Pebble directly as a remote), we wanted the Nest to be controlled with more of a passive input.
How it works
We used the Pebble watch to attempt to sense whether a person was standing still or running (swinging arms). In response, the Nest thermostat would lower the temperature.
The Pebble processes accelerometer data and sends a request to a server hosted on AWS, which processes the request and changes the temperature via the Nest API.
Implementation could be extended to monitor more activities, e.g. sleep in response to inactivity or a change in ambient light.