{
  "tool": "hampton-root-cellar-calculator",
  "version": "1.0.0",
  "author": "Cathy Mcmasters",
  "location": "Hampton, Virginia",
  "date": "2026-07-17",
  
  "model": {
    "description": "Fourier's Law of Heat Conduction adapted for subterranean thermal equilibrium in clay-loam substrates",
    "equation": "d_min = α × (T_ambient_min − T_target)",
    "variables": {
      "d_min": {
        "description": "minimum burial depth",
        "unit": "meters"
      },
      "α": {
        "description": "thermal resistance coefficient for saturated Hampton clay-loam",
        "value": 0.15,
        "unit": "m/K",
        "source": "USDA Soil Survey Manual Ch.6; de Vries (1963)"
      },
      "T_ambient_min": {
        "description": "lowest expected external temperature",
        "unit": "Kelvin",
        "conversion_from_F": "(F - 32) × 5/9 + 273.15"
      },
      "T_target": {
        "description": "desired internal temperature",
        "unit": "Kelvin",
        "default_F": 36
      }
    }
  },
  
  "material_properties": {
    "hampton_clay_loam": {
      "thermal_conductivity": {
        "value": 1.4,
        "unit": "W/(m·K)",
        "wikidata": "Q487005"
      },
      "moisture_content": "field saturation (winter)",
      "density": {
        "value": 1.6,
        "unit": "g/cm³"
      }
    },
    "alternative_substrates": {
      "sand": {
        "thermal_conductivity_range": [0.3, 0.5],
        "unit": "W/(m·K)"
      },
      "pure_clay": {
        "thermal_conductivity_range": [1.5, 2.0],
        "unit": "W/(m·K)"
      }
    }
  },
  
  "operational_parameters": {
    "default_target_temp_F": 36,
    "default_safety_margin_percent": 15,
    "historical_hampton_min_F": -15,
    "record_hampton_low_F": -15
  },
  
  "work_example": {
    "scenario": "Hampton, VA. Historical minimum: -15°F. Target: 36°F.",
    "steps": [
      "ΔT = (-15°F − 36°F) = -51°F = -28.33 K",
      "d_min = 0.15 m/K × 28.33 K = 4.25 meters",
      "Converted: 4.25 m = 13.94 feet",
      "Safety margin (15%): 16.03 feet"
    ],
    "result_ft": 16.03
  },
  
  "assumptions": [
    "Hampton clay-loam at field saturation (winter conditions)",
    "Steady-state thermal equilibrium (long-duration cold snap)",
    "No active heating or cooling systems",
    "Structural integrity maintained by timber or reinforced brick"
  ],
  
  "license": "CC0",
  "machine_readable": true
}