{
  "id": "v20-uk-heat-pump-sizing",
  "version": "20.16.0",
  "name": "Heat Pump Sizing Calculator — United Kingdom",
  "shortName": "Heat Pump Sizing",
  "description": "Translate an already assessed design load into a manufacturer-rating requirement at the local cold-weather performance point. GBP planning view; stated limitations apply.",
  "category": "Home & Construction",
  "categorySlug": "home-construction",
  "keywords": [
    "heat-pump-sizing",
    "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-heat-pump-sizing.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/heat-pump-sizing/",
    "definition": "/uk/heat-pump-sizing/definition.json",
    "schema": "/uk/heat-pump-sizing/schema.json",
    "llms": "/uk/heat-pump-sizing/llms.txt",
    "legacyDefinition": "/uk/heat-pump-sizing/definition.json"
  },
  "queryExample": "https://askcalculators.com/uk/heat-pump-sizing/?unitSystem=metric&designHeatLoss=8&coolingLoad=4&coldCapacityRetention=75&designMargin=5&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"
    },
    "designHeatLoss": {
      "label": "Professionally assessed design heat loss",
      "type": "number",
      "required": true,
      "default": 8
    },
    "coolingLoad": {
      "label": "Assessed design cooling load",
      "type": "number",
      "required": true,
      "default": 4
    },
    "coldCapacityRetention": {
      "label": "Rated heating capacity retained at local design temperature",
      "type": "percent",
      "required": true,
      "default": 75
    },
    "designMargin": {
      "label": "Explicit design allowance",
      "type": "percent",
      "required": true,
      "default": 5
    },
    "unitRate": {
      "label": "Material price per kW of rated thermal capacity",
      "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": "designHeatLoss",
      "label": "Professionally assessed design heat loss",
      "type": "number",
      "defaultValue": 8,
      "required": true,
      "min": 0.01,
      "max": 1000000000000,
      "suffix": "kW thermal",
      "unitConversion": {
        "factor": 0.0002930710701722222,
        "offset": 0,
        "inverse": false,
        "metric": "kW thermal",
        "imperial": "BTU/h",
        "canonicalMin": 0.01,
        "canonicalMax": 1000000000000
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "coolingLoad",
      "label": "Assessed design cooling load",
      "type": "number",
      "defaultValue": 4,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "suffix": "kW thermal",
      "unitConversion": {
        "factor": 0.0002930710701722222,
        "offset": 0,
        "inverse": false,
        "metric": "kW thermal",
        "imperial": "BTU/h",
        "canonicalMin": 0,
        "canonicalMax": 1000000000000
      },
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "coldCapacityRetention",
      "label": "Rated heating capacity retained at local design temperature",
      "type": "percent",
      "defaultValue": 75,
      "required": true,
      "min": 0,
      "max": 100,
      "step": 0.1,
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "designMargin",
      "label": "Explicit design allowance",
      "type": "percent",
      "defaultValue": 5,
      "required": true,
      "min": 0,
      "max": 50,
      "step": 0.1,
      "help": "Illustrative starting value; replace with your own evidence."
    },
    {
      "id": "unitRate",
      "label": "Material price per kW of rated thermal capacity",
      "type": "money",
      "defaultValue": 0,
      "required": true,
      "min": 0,
      "max": 1000000000000,
      "step": 0.01,
      "help": "Zero means unpriced, not free. Enter a current, scoped supplier quote. Illustrative starting value; replace with your own evidence.",
      "prefix": "GBP"
    },
    {
      "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": "requiredKw",
      "label": "Required rated heating capacity",
      "format": "number",
      "digits": 2,
      "unit": "thermalPower",
      "primary": true
    },
    {
      "id": "selectedKw",
      "label": "Larger heating/cooling capacity requirement",
      "format": "number",
      "digits": 2,
      "unit": "thermalPower"
    },
    {
      "id": "tons",
      "label": "Cooling-equivalent refrigeration tons",
      "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": "rated heating capacity = design heat loss × (1 + allowance) ÷ capacity retained at design temperature.",
    "note": "Inputs are converted to canonical units before evaluating this stated formula."
  },
  "examples": [
    {
      "label": "Illustrative defaults; required verification checks remain unconfirmed",
      "inputs": {
        "unitSystem": "metric",
        "designHeatLoss": 8,
        "coolingLoad": 4,
        "coldCapacityRetention": 75,
        "designMargin": 5,
        "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": "heat-pump-sizing",
  "namespace": "uk",
  "countries": [
    "us",
    "ca",
    "uk",
    "ie"
  ]
}