{
  "title": "PropBeaver Energy Playground — evidence register v2",
  "evidenceStatus": "Single-upgrade references are sourced. Combining them and transferring EST currency estimates to this budget are explicit PropBeaver assumptions; the package result is not validated or measured.",
  "scenario": {
    "version": 2,
    "reviewed": "2026-10-23",
    "gasKwh": 10000,
    "electricityKwh": 2500,
    "gasUnitGBP": 0.0797,
    "electricityUnitGBP": 0.2632,
    "gasStandingGBP": 0.2968,
    "electricityStandingGBP": 0.5483,
    "days": 365,
    "baselineSource": "need",
    "tariffSource": "tariff",
    "baselineNote": "Combines the separate 2024 England/Wales gas and electricity medians as a reference budget. It is not an observed single household or the mean bill for this illustrated house.",
    "tariffNote": "The quarterly rate snapshot is held constant for 365 days for comparison; it is not an annual tariff forecast or the headline price-cap amount.",
    "combination": "Apply each source-linked reduction to the remaining relevant fuel budget. Published GBP savings become fractions of the original gas/electricity budget; their underlying source tariff is not reconstructed. This transfer and the multiplicative package rule are PropBeaver assumptions, not measured package savings or SAP calculations.",
    "limitations": "NEED figures are population medians, including occupant responses, not predictions for individual installations. EST figures have different starting conditions and are published model estimates. Combining them does not validate a particular home, establish an uncertainty interval or guarantee that interaction is fully accounted for."
  },
  "challenge": {
    "points": 10,
    "targetPercent": 20
  },
  "sources": {
    "need": {
      "publisher": "DESNZ",
      "title": "NEED 2026, Figure 3.1 and Table 2.1",
      "published": "2026-06-11",
      "geography": "England and Wales; measures analysis excludes flats",
      "url": "https://www.gov.uk/government/statistics/national-energy-efficiency-data-framework-need-report-summary-of-analysis-2026/national-energy-efficiency-data-framework-need-report-summary-of-analysis-2026-accessible-webpage",
      "chart": "https://assets.publishing.service.gov.uk/media/6a2682da56e988a798b3875c/figure_3.1.svg"
    },
    "tariff": {
      "publisher": "Ofgem",
      "title": "Direct Debit average unit rates and standing charges",
      "period": "1 October–31 December 2026",
      "geography": "Great Britain average, not a London-specific tariff",
      "url": "https://www.ofgem.gov.uk/your-energy-supply/your-energy-bill/energy-price-cap-unit-rates-and-standing-charges"
    },
    "glazing": {
      "publisher": "Energy Saving Trust",
      "title": "Windows and doors",
      "published": "2026-05-20",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/windows-and-doors/"
    },
    "draught": {
      "publisher": "Energy Saving Trust",
      "title": "Draught proofing",
      "published": "2026-05-20",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/draught-proofing/"
    },
    "controls": {
      "publisher": "Energy Saving Trust",
      "title": "Thermostats and heating controls",
      "published": "2026-09-28",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/thermostats-and-heating-controls"
    },
    "floor": {
      "publisher": "Energy Saving Trust",
      "title": "Floor insulation",
      "published": "2026-05-19",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/floor-insulation/"
    },
    "lighting": {
      "publisher": "Energy Saving Trust",
      "title": "Lighting",
      "published": "2026-10-06",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/lighting/"
    },
    "cylinder": {
      "publisher": "Energy Saving Trust",
      "title": "Insulating tanks and radiators",
      "published": "2025-11-03",
      "geography": "Great Britain",
      "url": "https://energysavingtrust.org.uk/advice/insulating-tanks-and-radiators/"
    }
  },
  "upgrades": [
    {
      "id": "glazing",
      "name": "Double glazing",
      "short": "A second layer of comfort.",
      "points": 4,
      "icon": "window",
      "effect": "glazing",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 85,
      "source": "glazing",
      "reference": "£85/year published estimate",
      "condition": "Entirely single-glazed semi-detached home upgraded to A-rated double glazing. Less if windows are already efficient.",
      "detail": "Uses EST’s GB £85 standalone estimate for single-to-double glazing; transferred to the example gas budget."
    },
    {
      "id": "wall",
      "name": "Cavity wall insulation",
      "short": "Keep warmth inside the walls.",
      "points": 3,
      "icon": "wall",
      "effect": "wall",
      "fuel": "gas",
      "kind": "metered-median",
      "fraction": 0.12,
      "source": "need",
      "reference": "12% metered gas reduction",
      "condition": "2023 installation cohort; 2024 gas savings, England/Wales houses. Not a solid-wall measure; assess cavity suitability and moisture.",
      "detail": "Uses the 12% gas-saving median in DESNZ NEED 2026, Figure 3.1."
    },
    {
      "id": "loft",
      "name": "Loft insulation",
      "short": "Improve the roof’s warm layer.",
      "points": 2,
      "icon": "roof",
      "effect": "loft",
      "fuel": "gas",
      "kind": "metered-median",
      "fraction": 0.03,
      "source": "need",
      "reference": "3% metered gas reduction",
      "condition": "2023 loft-upgrade cohort; existing insulation varies. This is not a specific bare-loft-to-270mm estimate.",
      "detail": "Uses the 3% gas-saving median in DESNZ NEED 2026, rather than assuming every loft starts bare."
    },
    {
      "id": "draught",
      "name": "Draught-proofing",
      "short": "Mind the little gaps.",
      "points": 1,
      "icon": "wind",
      "effect": "draught",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 55,
      "source": "draught",
      "reference": "£55/year published estimate",
      "condition": "Draughty windows, floors and doors in GB; keep required ventilation clear. Can overlap with window and floor upgrades.",
      "detail": "Uses EST’s GB £55 standalone estimate for draught-proofing windows, floors and doors."
    },
    {
      "id": "controls",
      "name": "Heating controls",
      "short": "Warmth when you need it.",
      "points": 1,
      "icon": "dial",
      "effect": "controls",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 100,
      "source": "controls",
      "reference": "£100/year published estimate",
      "condition": "Install and use an effective programmer, thermostat and radiator valves where the full set is missing. No bonus for merely buying a smart thermostat.",
      "detail": "Uses EST’s GB £100 estimate for installing and effectively using a full set of heating controls."
    },
    {
      "id": "solar",
      "name": "Solar panels",
      "short": "Put the daylight to work.",
      "points": 4,
      "icon": "sun",
      "effect": "solar",
      "fuel": "electricity",
      "kind": "metered-median",
      "fraction": 0.12,
      "source": "need",
      "reference": "12% metered grid reduction",
      "condition": "2023 PV cohort; 2024 imported-electricity savings in England/Wales houses. Panel sizes and household habits vary. No export income or battery benefit included.",
      "detail": "Uses NEED’s 12% median reduction in grid electricity, not 40% of a bill or total solar generation."
    },
    {
      "id": "floor",
      "name": "Floor insulation",
      "short": "A warmer home underfoot.",
      "points": 2,
      "icon": "floor",
      "effect": "floor",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 55,
      "source": "floor",
      "reference": "£55/year published estimate",
      "condition": "Insulate beneath ground-floor boards in an average GB house. Requires access, ventilation and moisture checks; not an upper-floor flat estimate.",
      "detail": "Uses EST’s £55/year GB average-house floor-insulation estimate."
    },
    {
      "id": "lighting",
      "name": "LED lighting",
      "short": "Same light. Less electricity.",
      "points": 1,
      "icon": "bulb",
      "effect": "lighting",
      "fuel": "electricity",
      "kind": "published-estimate",
      "amountGBP": 45,
      "source": "lighting",
      "reference": "£45/year published estimate",
      "condition": "Replace remaining halogen spotlights with LEDs. Savings do not apply if the home already uses LEDs.",
      "detail": "Uses EST’s GB £45 estimate for replacing remaining halogen spotlights."
    },
    {
      "id": "cylinder",
      "name": "Cylinder jacket",
      "short": "Keep stored hot water warmer.",
      "points": 1,
      "icon": "tank",
      "effect": "cylinder",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 45,
      "source": "cylinder",
      "reference": "£45/year published estimate",
      "condition": "Gas-heated hot-water cylinder with 25mm factory foam, topped up with an 80mm British Standard jacket. Not a combi boiler or already well-insulated cylinder.",
      "detail": "Uses EST’s GB £45 estimate for topping up a 25mm-foam cylinder with an 80mm jacket."
    },
    {
      "id": "boiler",
      "name": "New condensing boiler",
      "short": "Renew an ageing heating system.",
      "points": 4,
      "icon": "boiler",
      "effect": "boiler",
      "fuel": "gas",
      "kind": "metered-median",
      "fraction": 0.02,
      "source": "need",
      "reference": "2% metered gas reduction",
      "condition": "Median for replacement condensing-boiler installations in the 2023 cohort. Not the much larger saving from a specified G-rated boiler. Qualified installer required.",
      "detail": "Uses NEED’s 2% metered gas-saving median for replacement condensing boilers."
    },
    {
      "id": "thermostat",
      "name": "One degree lower",
      "short": "22°C to 21°C, if comfortable.",
      "points": 1,
      "icon": "thermometer",
      "effect": "thermostat",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 120,
      "source": "controls",
      "reference": "£120/year published estimate",
      "condition": "An existing room thermostat changes from 22°C to 21°C. Keep temperatures comfortable for occupants; comfort and health come first.",
      "detail": "Uses EST’s GB £120 estimate for a 22°C-to-21°C thermostat change, not a universal saving for every starting temperature."
    },
    {
      "id": "chimney",
      "name": "Unused chimney seal",
      "short": "Stop a chimney drawing warmth.",
      "points": 1,
      "icon": "chimney",
      "effect": "chimney",
      "fuel": "gas",
      "kind": "published-estimate",
      "amountGBP": 45,
      "source": "draught",
      "reference": "£45/year published estimate",
      "condition": "An unused open chimney only. Use an appropriate removable product; remove before lighting a fire. Never seal an active appliance flue or required ventilation.",
      "detail": "Uses EST’s GB £45 estimate for draught-proofing an unused open chimney."
    }
  ],
  "formula": "For each fuel: initialBudget * product(1 - standaloneReferenceSaving / initialBudget). Metered-median references use their published fraction. Then add unchanged standing charges.",
  "pricing": "Annual gas kWh * snapshot gas unit rate + annual imported electricity kWh * snapshot electricity unit rate + 365 * both daily standing charges.",
  "noClaims": [
    "No SAP/RdSAP or EPC rating",
    "No export income",
    "No guaranteed individual saving",
    "No measured package result",
    "No invented uncertainty bounds",
    "No source endorsement"
  ],
  "transcription": "DESNZ NEED 2026 Figure 3.1: cavity wall 12%, loft 3%, condensing boiler 2%, solar PV 12%. England/Wales 2023 installations, savings measured in 2024. EST GBP values use the GB amounts, not NI or combined water-bill savings."
}