All Energy & Sustainability Calculators
All tools →Energy
Solar Panel Payback Calculator
Cost, annual generation, electricity savings, SEG export income, payback period and 25-year ROI for residential PV.
Energy
Heat Pump vs Gas Boiler Calculator
15-year total cost of an air-source heat pump vs gas boiler, including UK BUS grant and CO₂ savings.
Energy
EV Charging Cost Calculator
Cost per charge, per mile and annual EV running cost vs petrol. Mix home, public AC and rapid DC tariffs.
Energy
Carbon Footprint Calculator
Estimate your annual CO₂ emissions from transport, home energy, diet and lifestyle. Compare to global averages.
Energy
AI Carbon Footprint Calculator
gCO₂e and kWh per LLM prompt by model and grid region. Compare GPT-4o, Claude, Gemini and Llama emissions.
Energy
Fuel Cost & MPG Calculator
Trip fuel cost, vehicle MPG / L/100km, cost per mile and annual fuel spend. Petrol, diesel and hybrid.
About Our Energy & Sustainability Calculators
Energy is one of the few household expenses where the right one-off decision pays back for decades. A well-sized solar PV array, a properly specified heat pump, or switching from petrol to electric can each cut a household's annual energy bill by £600–£2,000 — and the same decisions are now the single biggest individual lever on personal carbon emissions. These calculators help you put real numbers on those choices using 2026 UK and EU pricing, official grant amounts and clinical-trial-grade efficiency assumptions.
How These Tools Fit Together
The three "big-ticket" calculators — solar, heat pump and EV charging — are designed to be used together. A typical UK household electrification path looks like:
- Step 1 — measure your baseline with the Carbon Footprint Calculator and the Fuel Cost Calculator so you know what you're starting from.
- Step 2 — model the EV switch with the EV Charging Cost Calculator. Most households cut motoring fuel by 50–70%.
- Step 3 — model heating electrification with the Heat Pump vs Gas Boiler Calculator. Pair with a heat-pump tariff (Octopus Cosy, OVO Heat Pump Plus) for break-even versus gas.
- Step 4 — install solar to cover the new electric load using the Solar Panel Payback Calculator. EV + heat pump dramatically lift self-consumption, which is the killer variable in solar economics.
UK 2026 Policy Snapshot
- Boiler Upgrade Scheme (BUS): £7,500 toward an air-source or ground-source heat pump, confirmed through 2028
- 0% VAT on residential solar & battery storage: in force until March 2027
- Smart Export Guarantee (SEG): Octopus Outgoing Fixed pays ~15p/kWh for exported solar (May 2026)
- EV Chargepoint Grant: £350 toward a home wallbox for flats & rented properties in England
- VED (road tax) on EVs: applies from April 2025; budget for ~£190/yr
- UK gas-boiler ban: proposed 2035 cut-off for new fossil-fuel boilers
US 2026 Policy Snapshot
- Federal Solar Investment Tax Credit (ITC): 30% of system cost, runs through 2032 under the Inflation Reduction Act
- HEEHRA / HOMES rebates: up to $14,000 per low-to-moderate-income household for heat pumps and other electrification (state-administered)
- EV tax credit: up to $7,500 new / $4,000 used, with strict income and assembly-location rules
- Net metering: varies by state — California NEM 3.0 cut export rates ~75% from 2023; check your utility
Important Note: These tools provide planning estimates using published 2026 grant amounts, fuel prices and efficiency benchmarks. Actual results depend on your roof, location, insulation, installer quality and weather. Always commission an MCS (UK) or NABCEP (US) certified site survey, and obtain at least three written quotes before committing to any major installation. Tariffs and grant schemes change — verify with the provider.