metering

German energy metering domain library — interval types, gas conversion, billing period aggregation, SLP/RLM/iMSys classification, and Hampel-filter quality scoring.

metering is the pure domain library used by edmd for all metering arithmetic. It has no I/O, no async, and no floating-point money.

Design constraints

Constraint	Detail
No I/O	All inputs are passed as arguments.
No async	Synchronous throughout.
No float money	All energy amounts use `rust_decimal`.
Deterministic	Same inputs always produce the same output.

Core types

`MeterInterval`

A single timestamped energy reading:

pub struct MeterInterval {
    pub period_start: OffsetDateTime,
    pub period_end: OffsetDateTime,
    pub value_kwh: Decimal,
    pub quality: QualityFlag,
}

`Sparte`

pub enum Sparte { Strom, Gas }

`QualityFlag`

Measured, Substituted, Estimated, Invalid — mapped to MSCONS/UTILTS Datenqualitätskennzeichen.

Gas conversion: m³ → kWh_Hs

pub fn gas_m3_to_kwh_hs(
    m3: Decimal,
    brennwert_kwh_m3: Decimal,
    zustandszahl: Decimal,
) -> Decimal

Implements the Brennwertkorrektur formula per §24 GasGVV / DVGW G 685:

$$kWh_{Hs} = m^3 \times z \times H_s$$

Billing period aggregation

aggregate computes a BillingPeriodAggregate from a slice of MeterIntervals:

let agg = aggregate(&intervals, &AggregationConfig::rlm_strom())?;
println!("kWh HT: {}", agg.kwh_ht);
println!("kWh NT: {}", agg.kwh_nt);
println!("Spitzenlast: {:?} kW", agg.spitzenleistung_kw);

`AggregationConfig` presets

Preset	Messtyp	Split
`rlm_strom()`	RLM	Spitzenleistung §2 Nr. 17 MessZV + HT/NT split
`slp_strom()`	SLP	HT/NT split (no Spitzenleistung)
`rlm_zweitarif()`	RLM	Custom HT/NT window
`gas()`	Gas	Single total (m³ → kWh_Hs, no tariff split)

SLP/RLM/iMSys classification

pub fn classify_messtyp(
    malo: &MaloId,
    jahresverbrauch_kwh: Decimal,
    sparte: Sparte,
) -> Messtyp

`Messtyp`	Criteria	Basis
`Slp`	< 100 MWh/a (Strom) or < 1.500 MWh/a (Gas)	§3 MessZV
`Rlm`	≥ 100 MWh/a (Strom) or ≥ 1.500 MWh/a (Gas)	§4 MessZV
`Imsys`	Pflichteinbau iMSys (§41a EnWG)	§41a EnWG

Mehr-/Mindermengensaldo

pub fn compute_imbalance(
    forecast_kwh: Decimal,
    actual_kwh: Decimal,
) -> ImbalanceResult

ImbalanceResult contains delta_kwh and delta_pct. Positive = Mehrmenge (actual > forecast); negative = Mindermenge. Basis: §27 MessZV.

Hampel-filter quality scoring

score_intervals runs a Hampel filter over a time-ordered slice of intervals and returns per-interval QualityGrades:

pub fn score_intervals(
    intervals: &[MeterInterval],
    window_k: usize,   // half-window size (default: 3)
    threshold: f64,    // MAD threshold in sigma units (default: 3.0)
) -> Vec<QualityGrade>

`QualityGrade`

Grade	Meaning	Effect in `edmd`
`A`	Clean — within threshold	Billing proceeds normally
`B`	Slightly suspicious	Logged; billing proceeds
`C`	Likely outlier	`de.edmd.reading.quality.warning` CloudEvent emitted
`F`	Severe outlier / substituted	Billing run blocked; operator alert

hampel_filter is also exposed as a low-level primitive that returns raw outlier indices.

Feature flags

Flag	Effect
`serde`	Derive `Serialize`/`Deserialize` on all public types

Testing

cargo test -p metering --all-features

37 tests covering gas conversion, aggregation (RLM/SLP/Gas), Messtyp classification, imbalance arithmetic, and Hampel filter edge cases.

Regulatory basis

§3, §4 MessZV — SLP/RLM classification thresholds
§2 Nr. 17 MessZV — Spitzenleistung definition for RLM
§27 MessZV — Mehr-/Mindermengensaldo
§24 GasGVV / DVGW G 685 — Gas Brennwertkorrektur
§41a EnWG — 15-Minuten-Lastgang and iMSys Pflichteinbau

metering 0.9.0