A new state class, total_increasing has been added. In addition, the
last_reset attribute is removed from SensorEntity. The driver for the changes is to
make it easier to integrate with devices, like utility meters.
State classes
There are 2 defined state classes:
measurement, the state represents a measurement in present time, for example a temperature, electric power, the value of a stock portfolio, etc. For supported sensors, statistics of hourly min, max and average sensor readings or of the accumulated growth or decline of the sensor's value since it was first added is updated hourly.total_increasing, a monotonically increasing total, e.g. an amount of consumed gas, water or energy. When supported, the accumulated growth of the sensor's value since it was first added is updated hourly.
STATE_CLASS_TOTAL_INCREASING
For sensors with state_class STATE_CLASS_TOTAL_INCREASING, a decreasing value is
interpreted as the start of a new meter cycle or the replacement of the meter. It is
important that the integration ensures that the value cannot erroneously decrease in
the case of calculating a value from a sensor with measurement noise present. This state
class is useful for gas meters, electricity meters, water meters etc.
The sensor's state when it's first added to Home Assistant is used as an initial zero-point. When a new meter cycle is detected the zero-point will be set to 0. Please refer to the tables below for how this affects the statistics.
Example of STATE_CLASS_TOTAL_INCREASING with a new meter cycle:
| t | state | sum |
|---|---|---|
| 2021-08-01T13:00:00 | 1000 | 0 |
| 2021-08-01T14:00:00 | 1010 | 10 |
| 2021-08-01T15:00:00 | 0 | 10 |
| 2021-08-01T16:00:00 | 5 | 15 |
Example of STATE_CLASS_TOTAL_INCREASING where the there initial state at the beginning
of the new meter cycle is not 0, but 0 is used as zero-point:
| t | state | sum |
|---|---|---|
| 2021-08-01T13:00:00 | 1000 | 0 |
| 2021-08-01T14:00:00 | 1010 | 10 |
| 2021-08-01T15:00:00 | 5 | 15 |
| 2021-08-01T16:00:00 | 10 | 20 |
This state class used to be represented by state class measurement in combination with a last_reset value. This approach has been deprecated and will be interpreted as a total_increasing state class instead with an automatic last reset.