How to use this: Pick a scenario button at the top to get started. Then slide the controls and choose the equipment in the cards below to match your family’s home: the furnace or heat pump, the water heater, the fridge, the lights, and how warm or cool you keep the thermostat. Everything updates right away. Watch the big orange tile to see energy per person and whether you beat the California average, then check the monthly chart to see when the bills spike. Try adding rooftop solar or an electric car and see what happens to the bill and the carbon. When you’re done, copy the link at the bottom to save your work or share it with your class.
Electric plus gas bill each month (orange) next to a typical home in your region (gray). Heating lands in winter, cooling in summer, and solar earns the most in June and July.
Site energy per year in kWh-equivalent (gas counted at 29.3 kWh per therm), typical home in your region vs. your scenario.
Move any lever. Each change is ranked here by the kWh-equivalent per year it saves for the whole household, after solar.
The link below encodes every slider. Anyone who opens it sees exactly this scenario.
Interaction pattern inspired by En-ROADS, created by Climate Interactive and MIT Sloan. Companion to the other wann.org sustainability simulators (carbon footprint, water, transportation, food, waste). Independent model, not affiliated with any utility.
Everything runs in your browser. Each end use is built from a cited annual figure for a Santa Monica home, then scaled by your region’s climate, your home’s size, the equipment you pick and your thermostat. Gas is converted to kWh-equivalent at 29.3 kWh per therm so the two fuels add up. Solar is subtracted from the electric bill and carbon, not from the site-energy headline.
The Home Energy Simulator estimates your yearly electricity and gas use, your energy bills and the carbon they cause. You can test upgrades such as LED lighting, a smart thermostat, insulation, a heat pump or heat pump water heater, and rooftop solar with or without a home battery, using editable price sliders for local utility rates.
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 Lab’s 2025 data, and export credits follow California’s Net Billing Tariff. Rates use published 2026 SCE, PG&E, SoCalGas and Clean Power Alliance rate sheets, and carbon uses EPA eGRID.
Key sources:
It depends on your bill, roof and utility rate. The federal 30% residential clean energy credit ended for systems installed after December 31, 2025, so payback is longer than before. Use the simulator to test your own numbers.
It is California’s Net Billing Tariff, which started in April 2023. It pays much less for solar power you send back to the grid, which makes pairing solar with a battery more valuable.
For many homes, heating and cooling are the biggest energy users, so sealing air leaks, adding insulation and switching to a heat pump often save the most. Results vary by climate and home.
Yes. Every price slider can be changed, so you can match your own utility bill.
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Built and reviewed by the Accessible Sustainability Alliance, a 501(c)(3) nonprofit operated by the Wann Heritage Foundation. Last updated October 5, 2026. Results are estimates for education and planning. Questions or corrections: contact@wann.org.