Public evidence

electrical.energy_cost

Machine-checked verification for calculation version 1.4.2 · tier internally_reviewed

Open calculator API Capability Download JSON CVP Manifest MCP Review policy

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· Flat unit rate only; no standing/fee (see electricity bill) · Protocol · Schema · Production report

Declared partition coverage: PASS · 3/3 declared partitions (watts, kwh, invalid-domain)
Versions: Calculation 1.4.2 · CVP protocol 1.0.0-proposed · Evidence 2026-09-13.ssr-dollar-literal
Verification revision: 2026-09-13.ssr-dollar-literal · 5/5 property · digest b2d8bb7116f1

Verification

Legacy regression suite: 28/28 calculation tests · Production surface contract 4/4

Three distinct suites: educational examples on the calculator page, this legacy regression count (28/28 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

This calculator CURRENT · Public schema 1.4.2 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Verification revision 2026-09-13.ssr-dollar-literal. Calculation version 1.4.2. CVP 1.0.0-proposed. 2/2 golden · 12/12 CVP boundary · 21/21 invalid · 5/5 property · 3/3 cross-interface · 4/4 CVP contract. digest b2d8bb7116f1.

Golden (oracle-backed) 2 / 2
CVP boundary 12 / 12
Invalid input 21 / 21
Property 5 / 5
Cross-interface 3 / 3
CVP contract 4 / 4
Interfaces PASS · UI (SSR) / REST / MCP
Interface claim ui-ssr is query-result HTML, not a live browser session. Public share URLs use UI ids (powerInput/hoursInput/daysInput/kwhInput/rateInput). CVP-IFACE includes those serialized queries, not only canonical engine keys.
Assurance Engineering

release artifacts aligned PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS

Fingerprint sha256:1d89897cd7c3a32f55a70b81d1f55258199ef0655d42352bb14163bbd0d01192

Input schema sha256:12262cc56ba4bd37d19d307cb4bd0bc5d9dce4fde5270bd9146c57e088dabaf9 · Output schema sha256:e11e90e9c7aa944658f65c395d04a726024128cf3a15b9b48dae535fb46aa2fa · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: energy-cost
Engine: energy-cost
Engine build: 2026-09-13
Evidence core: 2026-09-13T13:02:01.815Z
Rendered: 2026-09-16T22:03:43.702Z
Last reviewed: 2026-09-13

Assumptions

Constant average power over the period
Single flat unit rate

Limitations

Usage cost only — standing charge and tax not included
W, hours, days, kWh, and rate must be ≥ 0
Hours per day must be ≤ 24 (HOURS_PER_DAY_OUT_OF_RANGE)
Zero W/hours/days/kWh/rate → 0

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

NIST Guide to the SI (SP 811) — Kilowatt-hour as a common commercial unit of electrical energy
Supports: Cost = kWh × rate; kWh = W × h × days / 1000
U.S. Energy Information Administration (EIA) — Electricity prices reported per kilowatt-hour
Supports: Rate input ($/kWh) is user-supplied from local tariffs

Legacy published checks

Golden and boundary cases from the legacy Evidence JSON. CVP property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the Manifest — including SKIP when a suite has no vectors.

ID	Kind	Status	Detail
`watts-mode`	golden	pass	Expected 18 · Actual 18
`kwh-mode`	golden	pass	Expected 18 · Actual 18
`linear-2x-W`	golden	pass	Expected 36 · Actual 36
`linear-2x-rate`	golden	pass	Expected 36 · Actual 36
`soft-zero-W`	golden	pass	Expected 0 · Actual 0
`soft-zero-days`	golden	pass	Expected 0 · Actual 0
`soft-zero-rate`	golden	pass	Expected 0 · Actual 0
`soft-zero-kwh`	golden	pass	Expected 0 · Actual 0
`500W-2h-30d`	golden	pass	Expected 6 · Actual 6
`daily-1d`	golden	pass	Expected 2.25 · Actual 2.25
`missing-rate`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`bad-mode`	boundary	pass	Expected INVALID_MODE · Actual INVALID_MODE
`neg-rate`	boundary	pass	Expected VALUE_MUST_BE_NON_NEGATIVE · Actual VALUE_MUST_BE_NON_NEGATIVE
`boundary-zero-rate`	boundary	pass	Expected 0 · Actual 0
`boundary-neg-W`	boundary	pass	Expected VALUE_MUST_BE_NON_NEGATIVE · Actual VALUE_MUST_BE_NON_NEGATIVE
`boundary-neg-hours`	boundary	pass	Expected VALUE_MUST_BE_NON_NEGATIVE · Actual VALUE_MUST_BE_NON_NEGATIVE
`boundary-hours-gt-24`	boundary	pass	Expected HOURS_PER_DAY_OUT_OF_RANGE · Actual HOURS_PER_DAY_OUT_OF_RANGE
`boundary-neg-days`	boundary	pass	Expected VALUE_MUST_BE_NON_NEGATIVE · Actual VALUE_MUST_BE_NON_NEGATIVE
`boundary-neg-kWh`	boundary	pass	Expected VALUE_MUST_BE_NON_NEGATIVE · Actual VALUE_MUST_BE_NON_NEGATIVE
`boundary-missing-W`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-missing-hours`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-missing-days`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-missing-kWh`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`property-cost`	property	pass	cost = kWh·rate
`property-kwh-mode`	property	pass	kWh mode matches watts path
`property-linear-load`	property	pass	cost ∝ W
`property-linear-rate`	property	pass	cost ∝ rate
`property-linear-hours`	property	pass	cost ∝ hours