Techniques are provided for power optimization of home automation system devices (e.g., battery-powered devices). In one example embodiment, the power optimization is based on service states for a room associated with the device. A service state is determined for each of one or more services available in the room. The device is maintained in a low-power inactive state while there are no active services in the room. In response to at least one service being activated, the device transitions from the inactive state to a full-power in-use state. Such transition is performed preemptively, absent any current attempt to use the device by a user or another device. In response to expiration of a timer since a last use of the device or the transition to the in-use state was made and no actual use occurred, the device exits the in-use state and may eventually return to the inactive state.