Source: https://guthlabs.ai/docs/instruments/insulation-hvac-btu-load-estimator-rule-of-thumb/
instrument / verified-clean
# Insulation/HVAC BTU Load Estimator (Rule of Thumb)
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Everyday & Life
**Tranche**: tranche-5
**Evidence ID**: t5-111
**Ledger rows**: 1
No ledger note is attached.
## Review findings
NEEDS_REVIEW because the exact climate-factor table, all modifier values and formulas, occupant input handling, area units, and suggested-unit-size mapping are unspecified. The four vectors use an explicitly illustrative convention only: base factors of 20/25/30 BTU/hr/sq ft, supplied multiplicative modifiers, and ceiling modifier equal to ceiling_height_ft/8. This convention is not established by the instrument specification and must not be treated as a validated HVAC method.
### Formula and scope findings
- The formula is only a schematic: no actual climate-zone base-factor table is supplied, so the calculation is not reproducible or verifiable.
- Insulation, sun-exposure, ceiling-height, and occupant modifier values and combination rules are unspecified.
- The inputs list omits occupants even though occupants are named as a modifier.
- No formula or sizing rule is supplied for the claimed suggested unit size range.
- A single 20-30 BTU/sq ft baseline is not universally valid for heating and cooling, and heating and cooling loads normally require separate calculations.
### Unit assumptions
- BTU requirement means BTU/hr, although the formula should label the output explicitly as BTU/hr.
- Room area is assumed to be in square feet when multiplied by BTU/sq ft.
- The illustrative vectors use ceiling height in feet and a normalized 8-foot reference height.
- The illustrative vectors use multiplicative insulation, sun, ceiling, and occupant modifiers.
- For the metric conversion vector, 1 m² = 10.7639 sq ft.
- The supplied rule-of-thumb factors are treated as heuristic values, not code-compliant or Manual J results.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
The estimator overflows to Infinity for an extreme but numerically representable area, and its result is convention-sensitive because the specification does not define whether sun exposure raises cooling load or lowers heating load, whether ceiling height is in feet or metres, or how BTU/hr maps to a suggested unit-size range.
## 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": {
"area_sq_ft": 400,
"climate_zone": "mild",
"base_factor_btu_per_sq_ft": 20,
"insulation_modifier": 0.9,
"sun_exposure_modifier": 0.9,
"ceiling_height_ft": 8,
"ceiling_reference_ft": 8,
"ceiling_modifier": 1,
"occupants": 2,
"occupant_modifier": 1
},
"expected_outputs": {
"estimated_btu_per_hr": 6480,
"suggested_unit_size_range": null
},
"working": "400 sq ft × 20 BTU/hr/sq ft = 8,000 BTU/hr; 8,000 × 0.9 insulation = 7,200; 7,200 × 0.9 sun exposure = 6,480; 6,480 × 1 ceiling modifier × 1 occupant modifier = 6,480 BTU/hr. Suggested unit range cannot be computed because no sizing-range rule is supplied."
}
````
## 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`