Multilayer wall R-value & U-value API

Computes the composite (series) thermal resistance R = R_in + Σ(t_i/k_i) + R_out, overall U = 1/R, heat flux, and total heat loss for a multilayer building assembly with optional air-film resistances. Answers 'What is the R-value of this wall assembly?', 'What is the U-value and heat loss through a multilayer wall?'.

Price$0.04per request

MethodPOST

Route/v1/engineering/wall-rvalue

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

engineeringthermofluidsr-valueu-valueinsulationconductionwallhvacbuilding-envelope

API URLhttps://x402.hexl.dev/v1/engineering/wall-rvalue

Integration docs

Example request

{
  "layers": [
    {
      "name": "drywall",
      "thicknessM": 0.0127,
      "conductivityWmK": 0.17
    },
    {
      "name": "insulation",
      "thicknessM": 0.09,
      "conductivityWmK": 0.04
    },
    {
      "name": "brick",
      "thicknessM": 0.1,
      "conductivityWmK": 0.72
    }
  ],
  "areaM2": 10,
  "deltaTempK": 20,
  "insideFilmResistance": 0.13,
  "outsideFilmResistance": 0.04
}

Example response

{
  "layerCount": 3,
  "perLayer": [
    {
      "name": "drywall",
      "rValueM2KW": 0.074706
    },
    {
      "name": "insulation",
      "rValueM2KW": 2.25
    },
    {
      "name": "brick",
      "rValueM2KW": 0.138889
    }
  ],
  "insideFilmResistance": 0.13,
  "outsideFilmResistance": 0.04,
  "totalResistanceM2KW": 2.633595,
  "overallUValueWm2K": 0.379709,
  "formula": "R_total = R_in + Σ(t_i/k_i) + R_out ; U = 1/R_total",
  "interpretation": "Lower U (higher R) means a better-insulated assembly.",
  "deltaTempK": 20,
  "heatFluxWm2": 7.594182,
  "areaM2": 10,
  "heatLossW": 75.941821
}

Input schema

{
  "type": "object",
  "required": [
    "layers"
  ],
  "properties": {
    "layers": {
      "type": "array",
      "description": "ordered layers; each { thicknessM, conductivityWmK } or { rValue }",
      "items": {
        "type": "object"
      },
      "examples": [
        [
          {
            "name": "insulation",
            "thicknessM": 0.09,
            "conductivityWmK": 0.04
          }
        ]
      ]
    },
    "areaM2": {
      "type": "number",
      "description": "wall area (m^2) for total heat loss"
    },
    "deltaTempK": {
      "type": "number",
      "description": "inside-outside temperature difference (K)"
    },
    "insideFilmResistance": {
      "type": "number",
      "description": "inside surface (film) resistance (m^2·K/W)"
    },
    "outsideFilmResistance": {
      "type": "number",
      "description": "outside surface (film) resistance (m^2·K/W)"
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}