Semantics of Reading Type are muddled
First, what Reading Type is not
- It is not what is being measured, that is in ItemBase
- It is not the address of the [resource], that is in subject
- It is not the address of the Meter, that is in dataSource
Reading type is an optional element of reports that indicates how this reading was made. Current enumerations are:
- Accumulation - Reading is accumulated over time, so that measured value must be computed by subtracting previous reading.
- Mean - Reading is the mean value over the period indicated in Granularity.
- Derived - Reading is derived through computations applied to some behavior or activity and perhaps a subset of an observation.
- Peak - Reading is Peak (highest) value over the period indicated in granularity.
I think that this more obscure than it needs to be.
When working in buildings, I think of these approaches:
- Direct Read - Reading is read from a device that increases monotonically, and usage must be computed from pairs of start and stop readings.
- Net - Meter or [resource] prepares its own calculation of total use over time
- Allocated—Meter covers several [resources] and usage is inferred through some sort of pro rata computation.
- Summed - Several meters together provide the reading for this [resource]. This is specifically a different than aggregated, which refers to multiple [resources] in the same payload. See also Hybrid.
- Derived - Usage is inferred through knowledge of run-time, normal operation, etc.
- Mean – Reading is the mean value over the period indicated in Granularity.
- Peak - Reading is Peak (highest) value over the period indicated in granularity. For some measurements, it may make more sense as the lowest value. May require special handling for aggregate readings. Only valid for flow-rate itemBases, i.e., Power not Energy.
- Hybrid - if aggregated, refers to different means reading types in the aggregate number.
To this list, for DR, I might add
- Contract - unmetered [resource] is reported at agreed upon rates.
- Projected - reading is in future and is not yet measured
Comments very welcome