Methodology and sources

Calculations

Calculator formulas live in pure typed modules outside interface components. Inputs, outputs, units, assumptions, validation, and numeric limits are explicit and deterministically tested. Domain results remain unrounded until presentation.

Electricity rates and bills

Cost tools use only the electricity rate and currency entered by the visitor. They do not select a regional rate or convert currencies. A simple kWh estimate does not automatically include taxes, fixed charges, tiers, time-of-use periods, demand charges, credits, or other tariff rules.

Representative appliance data

Lookup values describe published representative nameplate examples, not a promise about a specific model or household. Actual draw can change with size, mode, settings, cycling, and operating conditions. A nameplate, manufacturer specification, certification record, or safe measurement is more specific.

Source hierarchy

1. Government, regulators, and statistical authorities
2. Official program administrators and utilities
3. Manufacturers, certification bodies, and test datasets
4. Reputable research institutions
5. Secondary editorial sources for discovery or context only

Changing records

Rates, tariffs, incentives, specifications, and other changing values should preserve geography, units, effective or as-of date, source-updated date when available, last-verified date, update cadence, and material limitations.

Unknown is not zero

A missing value must not silently become zero or a fabricated default. Data refreshes should fail closed and retain known-good published data while surfacing failures for review.

Corrections

Corrections should record the source and reason, update verification dates, and trigger checks of dependent tools or generated outputs before publication. Use the contact and corrections page to report a problem.