Source: https://guthlabs.ai/docs/instruments/degree-day-energy-estimator/implementation/

instrument implementation / implementation-contract

# Degree-Day Energy Estimator implementation

A source-bound implementation contract for Degree-Day Energy Estimator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t5-173

**Effect**: Computation or source lookup only

## Input and validation requirements

Zero efficiency produces an undefined division and must be rejected; additionally, an unspoken Fahrenheit-versus-kelvin degree-day convention can change the result from 166.6666667 kWh to 300 kWh for the same numeric input.

## 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": {
    "mode": "heating",
    "UA_W_per_K": 250,
    "HDD_degree_days_C": 1800,
    "efficiency_eta": 0.9
  },
  "expected_outputs": {
    "seasonal_energy_Wh": 12000000,
    "seasonal_energy_kWh": 12000
  },
  "working": "UA·HDD·24/η = 250 W/K × 1800 K·day × 24 h/day ÷ 0.9 = 450000 W·day × 24 h/day ÷ 0.9 = 10800000 Wh ÷ 0.9 = 12000000 Wh = 12000 kWh."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/degree-day-energy-estimator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/degree-day-energy-estimator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/degree-day-energy-estimator/qualification/>)

## 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`