Degree-Day Energy Estimator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration

Tranche

tranche-5

Evidence ID

t5-173

Ledger rows

1

No ledger note is attached.

Review findings

The heating equation is dimensionally and conceptually valid as a rough sensible-load estimate under the stated assumptions. The specification needs an explicit cooling formula, a defined cooling performance input (preferably COP), degree-day base-temperature metadata, input validation, and clearly labeled units before implementation can be verified as complete.

Formula and scope findings

• The heating formula is standard only when UA is a whole-building heat-loss coefficient in W/K or kW/K, degree-days use the same temperature scale, and system efficiency η is a dimensionless delivered-to-input efficiency greater than zero.
• The cooling formula is not actually specified: 'similar for CDD cooling' does not define whether the denominator is a dimensionless efficiency, a coefficient of performance (COP), or another rating. Cooling normally uses Energy = UA·CDD·24/COP, with additional treatment often needed for latent cooling.
• The degree-day balance temperature or base temperature is not specified. HDD/CDD values depend on that temperature and cannot be interpreted unambiguously without it.
• A single constant UA and degree-day multiplication omits weather variation, solar gains, internal loads, ventilation/infiltration changes, thermal storage, part-load behavior, and for cooling, latent loads.

Unit assumptions

• For heating, UA is assumed to be W/K or kW/K, HDD is in degree-days on the matching temperature scale, 24 is hours per day, and η is dimensionless.
• With UA in W/K, the heating result is Wh; divide by 1000 for kWh. With UA in kW/K, the result is directly kWh.
• For cooling test calculations, the unspecified 'system efficiency' is interpreted as a dimensionless COP, so cooling energy equals UA·CDD·24/COP.
• Fahrenheit degree-days must be converted to Celsius/Kelvin degree-days by multiplying by 5/9 before combining with UA expressed per K.
• HDD/CDD are assumed to be nonnegative and based on a clearly stated balance/base temperature.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

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.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "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."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

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

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json