Calculate household energy cost and emissions

Calculate annual household electricity and gas consumption cost, location-based emissions, and an electricity-use change scenario.

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ToolHome Energy Calculator
Input
Output
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Preview

How it works

Each annual kWh total is multiplied by its tariff for cost and by the UK Government 2026 factor for emissions: 0.13096 kg CO2e/kWh for electricity and 0.18231 for gross-CV natural gas. The scenario changes electricity use only, holds gas and both tariffs constant, and subtracts the new totals from the current totals.

Formula
annual consumption cost = electricity kWh × electricity rate + gas kWh × gas rate
  • Zero gas use represents an all-electric home, while zero percentage change is a neutral scenario.
  • The electricity factor is location-based UK grid generation rather than a supplier-specific contractual claim.

Worked example

Cutting electricity use by 15 percent
3500 kWh electricity at 0.28/kWh, 12000 kWh gas at 0.07/kWh
Input
											Annual electricity kwh: 3500
Electricity price per kwh: 0.28
Annual gas kwh: 12000
Gas price per kwh: 0.07
Electricity change percent: -15
Output
												Current cost: 1820
Current co2e kg: 2646.08
New cost: 1673
New co2e kg: 2577.33
Cost saving: 147
Co2e saving kg: 68.75
Grid factor used: 0.13096
Gas factor used: 0.18231

When to use this

Annual energy statements provide kWh baselines, smart-meter exports support year-on-year comparisons, and insulation or appliance plans test a proposed electricity reduction against unchanged gas use.

Edge cases

  • Daily standing charges are absent from a per-kWh input, so the cost covers consumption charges rather than reproducing the full bill.
  • A renewable tariff does not change the location-based UK grid factor used here; contractual market-based reporting requires separate evidence.
  • A heat-pump conversion changes both electricity and gas, but this one-change scenario keeps gas fixed; compare separate before-and-after records for that switch.

References