Greenhouse Gas Emissions Calculator
ANA›Life Services Authority›National Calculator Authority›Greenhouse Gas Emissions Calculator
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Greenhouse Gas Emissions Calculator
Estimate your annual greenhouse gas (GHG) emissions in kilograms of CO₂ equivalent (kg CO₂e) from common sources including electricity consumption, natural gas usage, vehicle travel, and air travel.
### ⚡ Electricity
Monthly Electricity Usage (kWh)
Electricity Grid Region
US Average (0.386 kg CO₂e/kWh) Western US / WECC (0.233 kg CO₂e/kWh) Midwestern US / MRO (0.564 kg CO₂e/kWh) Eastern US / SERC (0.497 kg CO₂e/kWh) California (0.233 kg CO₂e/kWh) Pacific Northwest (0.233 kg CO₂e/kWh) Texas / ERCOT (0.450 kg CO₂e/kWh) EU Average (0.233 kg CO₂e/kWh) Australia (0.820 kg CO₂e/kWh) China (0.708 kg CO₂e/kWh) France (0.082 kg CO₂e/kWh) Canada (0.233 kg CO₂e/kWh)
### 🔥 Natural Gas
Monthly Natural Gas Usage (therms)
### 🚗 Vehicle Travel
Annual Miles Driven
Vehicle Fuel Efficiency (MPG)
Fuel Type
Gasoline (8.887 kg CO₂e/gallon) Diesel (10.180 kg CO₂e/gallon) E85 Ethanol Blend (5.500 kg CO₂e/gallon)
### ✈️ Air Travel
Short-Haul Flights per Year (< 3 hours, round trips)
Medium-Haul Flights per Year (3–6 hours, round trips)
Long-Haul Flights per Year (> 6 hours, round trips)
Flight Class
Economy Premium Economy Business Class First Class
Calculate Emissions
function greCalc() { var errors = [];
// Electricity var elecRaw = document.getElementById('gre-electricity').value.trim(); var gridFactor = parseFloat(document.getElementById('gre-grid').value); var elecMonthly = 0; if (elecRaw !== '') { elecMonthly = parseFloat(elecRaw); if (isNaN(elecMonthly) || elecMonthly 100000) errors.push('Monthly electricity usage seems unrealistically high (max 100,000 kWh).'); }
// Natural Gas var gasRaw = document.getElementById('gre-gas').value.trim(); var gasMonthly = 0; if (gasRaw !== '') { gasMonthly = parseFloat(gasRaw); if (isNaN(gasMonthly) || gasMonthly 10000) errors.push('Monthly natural gas usage seems unrealistically high (max 10,000 therms).'); }
// Vehicle var milesRaw = document.getElementById('gre-miles').value.trim(); var mpgRaw = document.getElementById('gre-mpg').value.trim(); var fuelFactor = parseFloat(document.getElementById('gre-fuel').value); var annualMiles = 0; var mpg = 0; var hasVehicle = (milesRaw !== '' || mpgRaw !== ''); if (hasVehicle) { if (milesRaw === '') errors.push('Please enter annual miles driven for vehicle calculation.'); if (mpgRaw === '') errors.push('Please enter vehicle fuel efficiency (MPG) for vehicle calculation.'); if (milesRaw !== '') { annualMiles = parseFloat(milesRaw); if (isNaN(annualMiles) || annualMiles 500000) errors.push('Annual miles driven seems unrealistically high (max 500,000).'); } if (mpgRaw !== '') { mpg = parseFloat(mpgRaw); if (isNaN(mpg) || mpg 200) errors.push('Vehicle fuel efficiency seems unrealistically high (max 200 MPG).'); } }
// Flights var shortRaw = document.getElementById('gre-short').value.trim(); var mediumRaw = document.getElementById('gre-medium').value.trim(); var longRaw = document.getElementById('gre-long').value.trim(); var classMult = parseFloat(document.getElementById('gre-class').value); var shortFlights = 0, mediumFlights = 0, longFlights = 0; if (shortRaw !== '') { shortFlights = parseFloat(shortRaw); if (isNaN(shortFlights) || shortFlights 365) errors.push('Short-haul flights per year cannot exceed 365.'); } if (mediumRaw !== '') { mediumFlights = parseFloat(mediumRaw); if (isNaN(mediumFlights) || mediumFlights 200) errors.push('Medium-haul flights per year cannot exceed 200.'); } if (longRaw !== '') { longFlights = parseFloat(longRaw); if (isNaN(longFlights) || longFlights 100) errors.push('Long-haul flights per year cannot exceed 100.'); }
// Check at least one input provided var anyInput = (elecRaw !== '' || gasRaw !== '' || milesRaw !== '' || shortRaw !== '' || mediumRaw !== '' || longRaw !== ''); if (!anyInput) errors.push('Please enter at least one emission source to calculate.');
var resultDiv = document.getElementById('gre-result'); if (errors.length > 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }
// ---- Calculations ----
// Electricity: annual kWh * emission factor // Annual kWh = monthly kWh * 12 var annualKwh = elecMonthly * 12; var elecEmissions = annualKwh * gridFactor; // kg CO2e
// Natural Gas: annual therms * 5.302 kg CO2e/therm (EPA factor) // 1 therm = 100,000 BTU; EPA: 53.02 kg CO2e per million BTU = 5.302 kg CO2e/therm var annualTherms = gasMonthly * 12; var gasEmissions = annualTherms * 5.302; // kg CO2e
// Vehicle: gallons used = miles / mpg; emissions = gallons * fuel factor var gallonsUsed = (mpg > 0) ? annualMiles / mpg : 0; var vehicleEmissions = gallonsUsed * fuelFactor; // kg CO2e
// Flights: // Short-haul round trip avg distance: ~800 km one-way = 1600 km RT // Medium-haul round trip avg distance: ~2500 km one-way = 5000 km RT // Long-haul round trip avg distance: ~8000 km one-way = 16000 km RT // ICAO emission factor economy: ~0.255 kg CO2e/km/passenger (includes radiative forcing multiplier of 1.9) // Base factor per km per passenger (economy): 0.255 kg CO2e/km var baseKgPerKm = 0.255; var shortKm = 1600; // round trip km var mediumKm = 5000; // round trip km var longKm = 16000; // round trip km
var shortEmissions = shortFlights * shortKm * baseKgPerKm * classMult; var mediumEmissions = mediumFlights * mediumKm * baseKgPerKm * classMult; var longEmissions = longFlights * longKm * baseKgPerKm * classMult; var flightEmissions = shortEmissions + mediumEmissions + longEmissions;
var totalEmissions = elecEmissions + gasEmissions + vehicleEmissions + flightEmissions;
// Convert to tonnes var totalTonnes = totalEmissions / 1000;
// US average for comparison: ~16 tonnes CO2e/year per person var usAvg = 16000; // kg var percentOfUsAvg = (totalEmissions / usAvg) * 100;
// Trees needed to offset (1 tree absorbs ~21.77 kg CO2/year) var treesNeeded = Math.ceil(totalEmissions / 21.77);
// Format numbers function fmt(n, d) { return n.toLocaleString('en-US', {minimumFractionDigits: d, maximumFractionDigits: d}); }
// Build breakdown rows var rows = ''; if (elecRaw !== '') { rows += '⚡ Electricity (' + fmt(annualKwh, 0) + ' kWh/yr)' + fmt(elecEmissions, 1) + ' kg' + fmt(elecEmissions/1000, 3) + ' t'; } if (gasRaw !== '') { rows += '🔥 Natural Gas (' + fmt(annualTherms, 1) + ' therms/yr)' + fmt(gasEmissions, 1) + ' kg' + fmt(gasEmissions/1000, 3) + ' t'; } if (milesRaw !== '' && mpgRaw !== '') { rows += '🚗 Vehicle (' + fmt(annualMiles, 0) + ' mi, ' + fmt(gallonsUsed, 0) + ' gal)' + fmt(vehicleEmissions, 1) + ' kg' + fmt(vehicleEmissions/1000, 3) + ' t'; } if (shortRaw !== '' || mediumRaw !== '' || longRaw !== '') { rows += '✈️ Air Travel (' + (shortFlights+mediumFlights+longFlights) + ' round trips)' + fmt(flightEmissions, 1) + ' kg' + fmt(flightEmissions/1000, 3) + ' t'; }
// Rating var rating = ''; if (totalTonnes ' + fmt(totalEmissions, 1) + ' kg CO₂e/year' + '= ' + fmt(totalTonnes, 3) + ' metric tonnes CO₂e/year' + '' + rating + '
' + 'This is ' + fmt(percentOfUsAvg, 1) + '% of the US average (16 t CO₂e/person/year).
' + '' + 'Sourcekg CO₂e/yrTonnes CO₂e/yr' + '' + rows + 'Total' + fmt(totalEmissions, 1) + ' kg' + fmt(totalTonnes, 3) + ' t' + '' + '🌳 To offset these emissions, you would need approximately ' + fmt(treesNeeded, 0) + ' trees growing for one year.
'; }
#### Formulas Used
Electricity Emissions (kg CO₂e): = Monthly kWh × 12 × Grid Emission Factor (kg CO₂e/kWh)
Natural Gas Emissions (kg CO₂e): = Monthly Therms × 12 × 5.302 kg CO₂e/therm (EPA factor: 53.02 kg CO₂e per million BTU; 1 therm = 100,000 BTU)
Vehicle Emissions (kg CO₂e): = (Annual Miles ÷ MPG) × Fuel Emission Factor (kg CO₂e/gallon) Gasoline: 8.887 kg CO₂e/gal | Diesel: 10.180 kg CO₂e/gal | E85: 5.500 kg CO₂e/gal
Flight Emissions (kg CO₂e): = Number of Round Trips × Round-Trip Distance (km) × 0.255 kg CO₂e/km × Class Multiplier Short-haul: 1,600 km RT | Medium-haul: 5,000 km RT | Long-haul: 16,000 km RT Class multipliers: Economy ×1.0 | Premium Economy ×1.5 | Business ×2.0 | First ×2.9 (Includes ICAO radiative forcing multiplier of 1.9 for high-altitude effects)
Total Emissions: = Electricity + Natural Gas + Vehicle + Flights (kg CO₂e/year)
Tree Offset: = Total Emissions ÷ 21.77 kg CO₂/tree/year
#### Assumptions & References
- Electricity emission factors sourced from the US EPA eGRID 2022 database by grid subregion.
- Natural gas emission factor of 5.302 kg CO₂e/therm from EPA Emission Factors for Greenhouse Gas Inventories (2023), including CO₂, CH₄, and N₂O.
- Gasoline emission factor of 8.887 kg CO₂e/gallon and diesel 10.180 kg CO₂e/gallon from EPA (2023). E85 factor accounts for biogenic carbon credit.
- Flight emission factors based on ICAO Carbon Emissions Calculator methodology with a radiative forcing index (RFI) multiplier of 1.9 applied to account for non-CO₂ warming effects at altitude (contrails, NOx, etc.).
- Business and first class multipliers reflect greater seat area and per-passenger fuel share per DEFRA/BEIS 2023 guidance.
- US average per-capita emissions of 16 metric tonnes CO₂e/year from EPA (2022).
- Tree sequestration rate of 21.77 kg CO₂/tree/year from US Forest Service estimates for average US tree species.
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