{
 "meta": {
  "name": "Part G water efficiency calculation factors (Table 1)",
  "source": "The Water Efficiency Calculator for New Dwellings (DCLG, 2009), as required by Approved Document G / Building Regulation 36",
  "publisher": "Energycount Ltd, energycount.co.uk",
  "licence": "Open data - reuse with attribution to energycount.co.uk",
  "version": "1.0 (2026-08-22)",
  "citation": "Energycount (2026), Part G water calculation factors dataset, https://energycount.co.uk/data/"
 },
 "constants": {
  "normalisation_factor": 0.91,
  "external_use_l_p_d": 5.0,
  "formula": "per-fitting consumption = capacity x use_factor + fixed_use; total x 0.91 + 5.0 = final l/p/d",
  "defaults": {
   "washing_machine_l_per_kg": 8.17,
   "dishwasher_l_per_place_setting": 1.25
  },
  "multiple_fittings_rule": "For taps and showers, use the higher of the arithmetic average and 70% of the highest-capacity fitting. For WCs, average effective flushing volume (1/3 full + 2/3 part)."
 },
 "fittings": [
  {
   "fitting": "WC single flush",
   "capacity_unit": "Flush volume (litres)",
   "use_factor": 4.42,
   "fixed_use_l_p_d": 0.0,
   "notes": "Single-flush cistern"
  },
  {
   "fitting": "WC dual flush - full flush",
   "capacity_unit": "Full flush volume (litres)",
   "use_factor": 1.46,
   "fixed_use_l_p_d": 0.0,
   "notes": "Scored with the part flush as two lines"
  },
  {
   "fitting": "WC dual flush - part flush",
   "capacity_unit": "Part flush volume (litres)",
   "use_factor": 2.96,
   "fixed_use_l_p_d": 0.0,
   "notes": "Methodology assumes ~2 part flushes per full flush"
  },
  {
   "fitting": "WC multiple fittings",
   "capacity_unit": "Average effective flushing volume (litres)",
   "use_factor": 4.42,
   "fixed_use_l_p_d": 0.0,
   "notes": "Effective flush = 1/3 full + 2/3 part"
  },
  {
   "fitting": "Taps excluding kitchen/utility",
   "capacity_unit": "Flow rate (litres/minute)",
   "use_factor": 1.58,
   "fixed_use_l_p_d": 1.58,
   "notes": ""
  },
  {
   "fitting": "Bath (shower also present)",
   "capacity_unit": "Capacity to overflow (litres)",
   "use_factor": 0.11,
   "fixed_use_l_p_d": 0.0,
   "notes": ""
  },
  {
   "fitting": "Shower (bath also present)",
   "capacity_unit": "Flow rate (litres/minute)",
   "use_factor": 4.37,
   "fixed_use_l_p_d": 0.0,
   "notes": ""
  },
  {
   "fitting": "Bath only (no shower)",
   "capacity_unit": "Capacity to overflow (litres)",
   "use_factor": 0.5,
   "fixed_use_l_p_d": 0.0,
   "notes": ""
  },
  {
   "fitting": "Shower only (no bath)",
   "capacity_unit": "Flow rate (litres/minute)",
   "use_factor": 5.6,
   "fixed_use_l_p_d": 0.0,
   "notes": ""
  },
  {
   "fitting": "Kitchen/utility sink taps",
   "capacity_unit": "Flow rate (litres/minute)",
   "use_factor": 0.44,
   "fixed_use_l_p_d": 10.36,
   "notes": ""
  },
  {
   "fitting": "Washing machine",
   "capacity_unit": "Litres per kg dry load",
   "use_factor": 2.1,
   "fixed_use_l_p_d": 0.0,
   "notes": "Default 8.17 l/kg where unspecified"
  },
  {
   "fitting": "Dishwasher",
   "capacity_unit": "Litres per place setting",
   "use_factor": 3.6,
   "fixed_use_l_p_d": 0.0,
   "notes": "Default 1.25 l/place setting where unspecified"
  },
  {
   "fitting": "Waste disposal unit",
   "capacity_unit": "Present = 1",
   "use_factor": 1.0,
   "fixed_use_l_p_d": 3.08,
   "notes": "Flat addition when fitted"
  },
  {
   "fitting": "Water softener",
   "capacity_unit": "Litres per person per day",
   "use_factor": 1.0,
   "fixed_use_l_p_d": 0.0,
   "notes": "Per Table 3 of the methodology"
  }
 ]
}