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The Accessible Sustainability Alliance (ASA) builds six free household sustainability calculators for students, families and teachers. This page explains how each one turns your answers into results, which public data sources it uses, what the results can and cannot tell you, and how to cite the calculators in schoolwork.
Quick answer: Our six calculators combine your inputs (household size, energy bills, trips, meals, trash and water habits) with published data from sources such as EPA eGRID, EIA RECS 2020, EPA WaterSense, EPA WARM, ReFED and Our World in Data. Results are estimates for learning and planning, not official audits, and every calculator runs in your browser with no sign-up.
You can open all six from the Sustainability Lab, which also combines your results into a Household Sustainability Score.
All six calculators follow the same basic recipe:
The Household Carbon Simulator estimates your household’s yearly carbon footprint in tons of CO2e. It adds up four big sources: home electricity, home heating fuel, driving and flying, and food and shopping.
Inputs: household size, electricity and gas use, miles driven, flights and diet. You can test changes such as rooftop solar, a heat pump, an electric vehicle or eating less meat.
How we calculate: Electricity emissions use regional emission factors from EPA eGRID. Fuel, vehicle and flight emissions use the EPA GHG Emission Factors Hub (2025). Typical household energy use comes from the U.S. Energy Information Administration’s Residential Energy Consumption Survey (RECS 2020). Solar output uses NREL PVWatts, and diet and shopping estimates draw on published lifecycle studies.
The Household Water Simulator estimates how many gallons your home uses each day, fixture by fixture: showers, toilets, faucets, laundry, dishwashing, leaks and outdoor watering. It compares your result in gallons per person per day with California’s indoor standard and shows the energy and carbon tied to pumping, treating and heating water. A drought stress test shows how your home would do under mandatory cutbacks.
How we calculate: Fixture use is based on the Water Research Foundation’s Residential End Uses of Water study (2016). Fixture flow rates come from EPA WaterSense and ENERGY STAR. The indoor benchmark comes from California’s SB 1157: 47 gallons per person per day from 2025, dropping to 42 in 2030. Outdoor estimates follow the state’s Model Water Efficient Landscape Ordinance (MWELO). Santa Monica figures use the city’s 2020 Urban Water Management Plan, and embedded energy uses California water-energy research and EPA eGRID.
The Home Energy Simulator estimates your yearly electricity and gas use, energy bills and carbon. You can test LED lighting, a smart thermostat, insulation, a heat pump or heat pump water heater, and rooftop solar with or without a home battery.
Inputs: home size, heating and cooling system, appliances and typical bills. Every price slider is editable to match your own utility rates.
How we calculate: Baseline use comes from EIA RECS 2020 state data. Appliance savings come from ENERGY STAR and the U.S. Department of Energy’s Energy Saver guides. Solar output uses NREL PVWatts. Solar and battery prices use Lawrence Berkeley National Laboratory’s Distributed Solar and Storage 2025 Data Update. Credits for solar power sent to the grid follow California’s Net Billing Tariff, often called NEM 3.0, which applies to customers who applied to connect on or after April 15, 2023. Carbon uses EPA eGRID. The simulator reflects that the federal 30 percent residential clean energy credit ended for systems installed after December 31, 2025.
The Household Waste Simulator estimates how many pounds of trash, recycling and compost your home sets out each week, and what happens to it. You can turn on swaps like composting, refill containers or buying in bulk and compare landfill pounds, recycling rate and greenhouse gas impact before and after.
How we calculate: Material amounts use EPA’s Facts and Figures about Materials, Waste and Recycling, which reports about 4.9 pounds of municipal solid waste per person per day. Greenhouse gas impacts use EPA’s Waste Reduction Model (WARM). California rules come from CalRecycle’s SB 1383 organics program, which requires every jurisdiction to offer organic waste collection to all residents and businesses. Local defaults use Santa Monica’s Zero Waste plan and rate table, and food waste figures use ReFED.
My Transportation Simulator compares the yearly cost, time and carbon of how your household gets around: gas car, hybrid, EV, bus, train, bike, walking and ride-hailing. It is set up for Los Angeles and Santa Monica trips by default, with LA Metro and Big Blue Bus fares, and you can switch regions.
How we calculate: Vehicle emissions use the EPA GHG Emission Factors Hub (2025). EV charging emissions use EPA eGRID regional grid factors. Trip patterns use the 2022 National Household Travel Survey. Driving costs use AAA’s Your Driving Costs (2025), transit fares use LA Metro and Big Blue Bus, ride-hailing impacts use Union of Concerned Scientists research, and physical activity guidance comes from the CDC.
The Food & Diet Simulator estimates the carbon, land and water footprint of what your household eats in a year, plus the food you throw away. You set weekly servings of each food group and compare swaps.
How we calculate: Food footprints use the Poore and Nemecek (2018) global food lifecycle dataset as presented by Our World in Data, which finds food systems cause about 26 percent of global greenhouse gas emissions. Water footprints use Mekonnen and Hoekstra’s Water Footprint Network research. Food waste figures use ReFED’s U.S. Food Waste Report, diet guidance references the EAT-Lancet Commission, and U.S. diet data uses USDA’s Economic Research Service.
Our calculators are teaching and planning tools. They show which changes matter most and roughly how big each piece of your footprint is. They are not an energy audit, a water audit or an official carbon inventory.
Keep these limits in mind:
When a source publishes a new edition, such as a new eGRID release or a new ReFED report, we review it and update the affected calculators and their source lists. Each calculator page shows a “Last updated” date at the bottom. If you are using a result in a report, note the date you ran it.
The calculators run in your web browser. There is no account and no sign-up, and you do not need to enter your name, address or email to get results. If you use the option to save or share a results link, anyone you give that link to can see the results it shows, so share it only with people you choose.
You are welcome to cite the calculators in reports, slides and science fair projects. We suggest this APA-style format:
Accessible Sustainability Alliance. (2026). Household Water Simulator [Online calculator]. Wann Heritage Foundation. https://wann.org/sustainability-calculators/water-calculator/
Swap in the name and web address of the calculator you used, and add the date you accessed it if your teacher asks for one. If you quote a specific number, also cite the original data source listed on that calculator’s page, such as EPA or EIA.
We want these tools to be accurate. If you spot an error, an outdated number or a broken source link, email contact@wann.org with the calculator name, what you entered and what looks wrong.
No. They are estimates built from public averages and your inputs. They are best for comparing options and spotting your biggest impacts, not for exact billing or official reporting.
The Accessible Sustainability Alliance is based in the Santa Monica area, so local utilities, fares and water rules are the default. Every calculator has a region picker so you can switch to your own area.
The calculators run in your browser and need no sign-up, name or email. If you create a share link, only people you send it to can see those results.
Yes. All six are free for classrooms and written at about an 8th-grade reading level. Students can cite them using the format above, and teachers can contact us at contact@wann.org for ideas.
Start with any calculator below. Each takes about five minutes, and the Sustainability Lab combines your results into one Household Sustainability Score.
Written and reviewed by the Accessible Sustainability Alliance editorial team. Last updated October 5, 2026.
The Wann Heritage Foundation /d/b/a The Accessible Sustainability Alliance is a 501(c)3 non-profit organization dedicated to making sustainable living accessible to everyone. We evaluate new, cost-effective, sustainable, and energy-efficient consumer alternatives, providing unbiased information and resources to help consumers make informed daily choices.