{
  "id": "v20-uk-attic-insulation",
  "version": "20.16.0",
  "name": "Attic Insulation Calculator — United Kingdom",
  "shortName": "Attic Insulation",
  "description": "Estimate attic insulation quantity and heating savings while keeping moisture, ventilation and local resistance requirements outside the arithmetic. GBP planning view; stated limitations apply.",
  "category": "Home & Construction",
  "categorySlug": "home-construction",
  "keywords": [
    "attic-insulation",
    "uk",
    "energy-conservation",
    "pvwatts",
    "energy-saver"
  ],
  "status": "live",
  "workStatus": "pending",
  "reviewStatus": "pending",
  "migrationStatus": "new",
  "engine": "native",
  "creator": null,
  "reviewer": null,
  "quality": {
    "availability": "live",
    "technicalReviewRecord": "/reviews/v20-uk-attic-insulation.json",
    "qualifiedReview": "pending",
    "qualifiedReviewer": null,
    "qualifiedReviewDate": null,
    "formulaVersion": "20.16.0",
    "referenceCoverage": "references-listed",
    "releaseTestScope": "Catalog and regression checks are not a professional formula audit; consult release evidence.",
    "historicalMetadataDate": "",
    "historicalMetadataNotice": "The imported date is not evidence of a completed human review."
  },
  "notice": "Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.",
  "urls": {
    "page": "/uk/attic-insulation/",
    "definition": "/uk/attic-insulation/definition.json",
    "schema": "/uk/attic-insulation/schema.json",
    "llms": "/uk/attic-insulation/llms.txt",
    "legacyDefinition": "/uk/attic-insulation/definition.json"
  },
  "queryExample": "https://askcalculators.com/uk/attic-insulation/?unitSystem=metric&area=80&oldResistance=2&newResistance=6&degreeDays=2500&heatingEfficiency=90&energyRate=0.1&addedDepth=150&unitRate=0&laborCost=0&deliveryCost=0&otherCost=0&costMultiplier=1&spreadPercent=15&taxRate=0",
  "queryParameters": {
    "unitSystem": {
      "label": "Measurement system",
      "type": "select",
      "required": false,
      "default": "metric"
    },
    "area": {
      "label": "Attic floor area",
      "type": "number",
      "required": true,
      "default": 80
    },
    "oldResistance": {
      "label": "Existing total assembly resistance",
      "type": "number",
      "required": true,
      "default": 2
    },
    "newResistance": {
      "label": "Proposed total assembly resistance",
      "type": "number",
      "required": true,
      "default": 6
    },
    "degreeDays": {
      "label": "Local annual heating degree days",
      "type": "number",
      "required": true,
      "default": 2500
    },
    "heatingEfficiency": {
      "label": "Heating input-to-useful-heat efficiency",
      "type": "percent",
      "required": true,
      "default": 90
    },
    "energyRate": {
      "label": "Heating energy price per input kWh",
      "type": "money",
      "required": true,
      "default": 0.1
    },
    "addedDepth": {
      "label": "Added material depth",
      "type": "number",
      "required": true,
      "default": 150
    },
    "unitRate": {
      "label": "Material price per area unit",
      "type": "money",
      "required": true,
      "default": 0
    },
    "laborCost": {
      "label": "Total labor allowance",
      "type": "money",
      "required": true,
      "default": 0
    },
    "deliveryCost": {
      "label": "Delivery allowance",
      "type": "money",
      "required": true,
      "default": 0
    },
    "otherCost": {
      "label": "Other fixed costs",
      "type": "money",
      "required": true,
      "default": 0
    },
    "costMultiplier": {
      "label": "Material/labor multiplier",
      "type": "number",
      "required": true,
      "default": 1
    },
    "spreadPercent": {
      "label": "Low/high sensitivity around the entered total",
      "type": "percent",
      "required": true,
      "default": 15
    },
    "taxRate": {
      "label": "Explicit tax allowance",
      "type": "percent",
      "required": true,
      "default": 0
    }
  },
  "inputs": [
    {
      "id": "unitSystem",
      "label": "Measurement system",
      "type": "select",
      "defaultValue": "metric",
      "options": [
        {
          "value": "imperial",
          "label": "Imperial (US gallons / short tons where relevant)"
        },
        {
          "value": "metric",
          "label": "Metric"
        }
      ]
    },
    {
      "id": "area",
      "label": "Attic floor area",
      "type": "number",
      "defaultValue": 80,
      "required": true,
      "min": 0.01,
      "max": 1000000000000,
      "suffix": "m²",
      "unitConversion": {
        "factor": 0.09290304,
        "offset": 0,
        "inverse": false,
        "metric": "m²",
        "imperial": "ft²",
        "canonicalMin": 0.01,
        "canonicalMax": 1000000000000
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "oldResistance",
      "label": "Existing total assembly resistance",
      "type": "number",
      "defaultValue": 2,
      "required": true,
      "min": 0.01,
      "max": 100,
      "suffix": "RSI (m²·K/W)",
      "unitConversion": {
        "factor": 0.1761101838,
        "offset": 0,
        "inverse": false,
        "metric": "RSI (m²·K/W)",
        "imperial": "R (h·ft²·°F/BTU)",
        "canonicalMin": 0.01,
        "canonicalMax": 100
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "newResistance",
      "label": "Proposed total assembly resistance",
      "type": "number",
      "defaultValue": 6,
      "required": true,
      "min": 0.01,
      "max": 100,
      "suffix": "RSI (m²·K/W)",
      "unitConversion": {
        "factor": 0.1761101838,
        "offset": 0,
        "inverse": false,
        "metric": "RSI (m²·K/W)",
        "imperial": "R (h·ft²·°F/BTU)",
        "canonicalMin": 0.01,
        "canonicalMax": 100
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "degreeDays",
      "label": "Local annual heating degree days",
      "type": "number",
      "defaultValue": 2500,
      "required": true,
      "min": 0,
      "max": 20000,
      "suffix": "°C·days",
      "unitConversion": {
        "factor": 0.5555555555555556,
        "offset": 0,
        "inverse": false,
        "metric": "°C·days",
        "imperial": "°F·days",
        "canonicalMin": 0,
        "canonicalMax": 20000
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "heatingEfficiency",
      "label": "Heating input-to-useful-heat efficiency",
      "type": "percent",
      "defaultValue": 90,
      "required": true,
      "min": 0,
      "max": 100,
      "step": 0.1,
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "energyRate",
      "label": "Heating energy price per input kWh",
      "type": "money",
      "defaultValue": 0.1,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "step": 0.01,
      "prefix": "GBP",
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "addedDepth",
      "label": "Added material depth",
      "type": "number",
      "defaultValue": 150,
      "required": true,
      "min": 0,
      "max": 2000,
      "suffix": "mm",
      "unitConversion": {
        "factor": 25.4,
        "offset": 0,
        "inverse": false,
        "metric": "mm",
        "imperial": "in",
        "canonicalMin": 0,
        "canonicalMax": 2000
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "unitRate",
      "label": "Material price per area unit",
      "type": "money",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "help": "Zero means unpriced, not free. Enter a current, scoped supplier quote. Illustrative starting value; replace with your own evidence.",
      "prefix": "GBP",
      "suffix": "/m²",
      "unitConversion": {
        "factor": 0.09290304,
        "offset": 0,
        "inverse": true,
        "metric": "m²",
        "imperial": "ft²",
        "canonicalMin": 0,
        "canonicalMax": 1000000000000
      }
    },
    {
      "id": "laborCost",
      "label": "Total labor allowance",
      "type": "money",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "step": 0.01,
      "prefix": "GBP",
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "deliveryCost",
      "label": "Delivery allowance",
      "type": "money",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "step": 0.01,
      "prefix": "GBP",
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "otherCost",
      "label": "Other fixed costs",
      "type": "money",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "step": 0.01,
      "prefix": "GBP",
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "costMultiplier",
      "label": "Material/labor multiplier",
      "type": "number",
      "defaultValue": 1,
      "required": true,
      "min": 0.1,
      "max": 10,
      "step": 0.01,
      "help": "Use a verified regional index only when supplied. 1 is an unadjusted scenario, not a researched index. Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "spreadPercent",
      "label": "Low/high sensitivity around the entered total",
      "type": "percent",
      "defaultValue": 15,
      "required": true,
      "min": 0,
      "max": 100,
      "step": 0.1,
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "taxRate",
      "label": "Explicit tax allowance",
      "type": "percent",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 100,
      "step": 0.1,
      "help": "Illustrative starting value; replace with your own evidence."
    }
  ],
  "outputs": [
    {
      "id": "materialVolume",
      "label": "Added insulation volume",
      "format": "number",
      "digits": 2,
      "unit": "volume"
    },
    {
      "id": "annualInputSaving",
      "label": "Modeled annual heating input saved, kWh",
      "format": "number",
      "digits": 2
    },
    {
      "id": "annualSaving",
      "label": "Modeled annual energy saving",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "payback",
      "label": "Simple payback, years",
      "format": "number",
      "digits": 2
    },
    {
      "id": "materialCost",
      "label": "Material cost",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "laborCost",
      "label": "Labor allowance",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "deliveryCost",
      "label": "Delivery allowance",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "otherCost",
      "label": "Other specified costs",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "tax",
      "label": "Entered tax allowance",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "low",
      "label": "Low cost scenario",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    },
    {
      "id": "mid",
      "label": "Middle cost scenario",
      "format": "currency",
      "digits": 2,
      "primary": true,
      "currency": "GBP"
    },
    {
      "id": "high",
      "label": "High cost scenario",
      "format": "currency",
      "digits": 2,
      "currency": "GBP"
    }
  ],
  "formula": {
    "expression": "annual useful heat saved = area × (1/R-old − 1/R-new) × heating degree days × 24 ÷ 1,000.",
    "note": "Inputs are converted to canonical units before evaluating this stated formula."
  },
  "examples": [
    {
      "label": "Illustrative defaults; required verification checks remain unconfirmed",
      "inputs": {
        "unitSystem": "metric",
        "area": 80,
        "oldResistance": 2,
        "newResistance": 6,
        "degreeDays": 2500,
        "heatingEfficiency": 90,
        "energyRate": 0.1,
        "addedDepth": 150,
        "unitRate": 0,
        "laborCost": 0,
        "deliveryCost": 0,
        "otherCost": 0,
        "costMultiplier": 1,
        "spreadPercent": 15,
        "taxRate": 0
      }
    }
  ],
  "sources": [
    {
      "label": "DOE energy-use arithmetic",
      "url": "https://www.energy.gov/energysaver/save-electricity-and-fuel/appliances-and-electronics/estimating-appliance-and-home"
    },
    {
      "label": "PVWatts: site-specific solar estimation",
      "url": "https://pvwatts.nlr.gov/"
    },
    {
      "label": "DOE insulation overview",
      "url": "https://www.energy.gov/energysaver/weatherize/insulation"
    }
  ],
  "publicSlug": "attic-insulation",
  "namespace": "uk",
  "countries": [
    "us",
    "ca",
    "uk",
    "ie"
  ]
}