Duration

Usage impacts are assessed for a specific time duration given by the user as a query parameter.

When no duration is given, the impacts are measured for the all lifespans of the device.

Usage ratio

The usage ratio is the proportion of time the device is used during the given duration. When a device is always used, the usage ratio is 1. When a device is never used, the usage ratio is 0.

Users can give the usage ratio in the usage object.