kWh Cost / Energy Bill Estimator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t5-213

Effect

Computation or source lookup only

Input and validation requirements

The extreme finite-looking input values overflow ordinary JavaScript arithmetic and produce Infinity for energy and cost. The estimator needs range validation or explicit overflow handling. A second hazard is that the specification does not define a branch or physical limit at 24 hours/day, nor a calendar convention for month/year totals.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "power_W": 100,
    "hours_per_day": 5,
    "days": 30,
    "utility_rate_USD_per_kWh": 0.2
  },
  "expected_outputs": {
    "energy_per_day_kWh": 0.5,
    "energy_for_days_kWh": 15,
    "energy_per_30_day_month_kWh": 15,
    "energy_per_365_day_year_kWh": 182.5,
    "cost_per_day_USD": 0.1,
    "cost_for_days_USD": 3,
    "cost_per_30_day_month_USD": 3,
    "cost_per_365_day_year_USD": 36.5
  },
  "working": "100 W ÷ 1000 = 0.1 kW. Daily energy = 0.1 kW × 5 h = 0.5 kWh. Energy for 30 days = 0.5 × 30 = 15 kWh. Energy for 365 days = 0.5 × 365 = 182.5 kWh. Daily cost = 0.5 kWh × $0.20/kWh = $0.10. Cost for 30 days = 15 × $0.20 = $3.00. Cost for 365 days = 182.5 × $0.20 = $36.50."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json