nuovo caso d'uso su smart metering

in line protocol:

org [measurement/tag]
* building [tag]
  * floor [tag]
    * asset [tag]
      * meter [field]
        * not decreasing value

in a table

tariff
* building
  * time-interval 

compute consumption 

```
|> aggWindow(1m, agg:last)
|> difference()
```

compute the cost

`join stream with table tariff`


