Household carbon calculator methodology
How EcoPal estimates tons CO₂e/year—factors, regional electricity rules, transportation assumptions, lifestyle categories, and benchmarks. Written for curious users and educators.
Purpose & inspiration
EcoPal’s household calculator is an educational tool for exploring annual greenhouse gas emissions (tons CO₂e/year) across housing, travel, food, goods, and waste. It is inspired by municipal and state tools such as CoolCalifornia / CARB, and by publicly documented EPA factors (eGRID electricity, GHG Equivalencies). It is not for regulatory reporting, carbon accounting inventories, or financial advice.
Units & output
- Results are shown in tons of CO₂-equivalent per year (tons CO₂e/yr)—the same “equivalent tons” framing used on other EcoPal calculators.
- Under the hood this is metric tons (1,000 kg). Combustion factors often start in lbs CO₂; we convert with 1 lb = 0.453592 kg, then kg → tons (÷ 1,000).
- Household total is the sum of categories; per-person = total ÷ occupants (1–10).
Electricity (eGRID-style by region)
We use simplified regional generation intensities (lbs CO₂ per kWh), approximated from EPA eGRIDsubregion-style rates, then multiply by a ~5% transmission & distribution factor (×1.051) for delivered electricity:
| Region | lbs CO₂/kWh (gen.) | eGRID-style hint |
|---|---|---|
| California | 0.429 | CAMX-like |
| Northeast | 0.54 | NEWE-like |
| Midwest | 0.95 | RFC/MRO mix |
| South | 0.82 | FRCC/SERC mix |
| West / Mountain | 0.65 | NWPP/AZNM mix |
| Other / US average | 0.767 | eGRID US |
Renewable offset % reduces electricity emissions linearly: × (1 − renewable%/100). Dollar mode converts monthly $ → kWh using ~$0.16/kWh (national residential ballpark).
Other housing fuels
- Natural gas: 11.7 lbs CO₂ / therm (EPA combustion factor). Dollar mode ≈ $1.20/therm.
- Heating oil: 22.4 lbs CO₂ / gallon.
- Propane: 12.7 lbs CO₂ / gallon.
Transportation
- Gasoline vehicles: gallons = miles ÷ MPG; × 19.6 lbs CO₂/gallon × 1.25 upstream (well-to-tank) multiplier.
- EVs: kWh = miles ÷ 3.5 mi/kWh, then × regional delivered electricity factor (same grid as home electricity).
- Public transit: ~0.089 kg CO₂e / mile × miles/week × 52.
- Flights (round trips/year): short ~500 mi × 0.24 kg/mi; medium ~1,500 mi × 0.20 kg/mi; long ~4,000 mi × 0.18 kg/mi (order-of-magnitude aviation intensities).
Food, goods & waste
- Diet (tons / person / year): meat-heavy 3.3 · average 2.5 · vegetarian 1.7 · vegan 1.1; multiplied by household size.
- Goods & services: base 3.2 tons / person × income bracket (0.75–1.55) × habit (low 0.7 / average 1.0 / high 1.4).
- Waste: base 0.8 tons / person; recycling −25%, composting −20% (floor at 35% of base).
These lifestyle categories are deliberately coarse—useful for ranking habits, not for formal consumption inventories.
Benchmarks
- US average ≈ 16 tons / person / year — illustrative US per-person footprint ballpark used for “% of US avg.”
- Personal goal ≈ 3 tons / person / year — science-aligned / Paris-path personal carbon budget range often cited near 2–4 tons; we use 3 as the on-screen target.
- Dashboard percentages compare your per-person result to those benchmarks—not the whole household total.
High-impact actions
Suggested actions estimate potential tons CO₂e savings from your current inputs (e.g. renewable share remaining on electricity, shifting diet, one fewer flight, EV / fewer miles, compost/recycle). They are sorted by estimated savings and capped to a short list—directional coaching, not guaranteed reductions.
Privacy
Answers are stored in your browser via localStorage so they persist across reloads on this device. Nothing is sent to EcoPal servers by this calculator.