WhyWatt? Home Electrification Explorer

Map your home electrification journey. Weigh the cost-benefit, then decide.

WhyWatt? is a community-developed, transparent tool to explore your electrification options, timeline, and benefits for your home.

ZIP  solar + your utility's rate plan 9  devices, solar & battery 20-yr  cost trajectories
WhyWatt Journey Timeline — heat-pump HVAC and water heater swaps on your journey vs. like-for-like replacements when doing nothing, over 20 years
Your journey — each device swap, placed on a 20-year timeline.
vs. doing nothing — the same devices, replaced like-for-like.
WhyWatt? · community electrification collaboration

02 · Meet WhyWatt · 1 of 3

The cockpit — your energy bottom line, up front

WhyWatt cockpit — break-even 2027, +$138,045 energy saving, two cost bars, cumulative energy-cost chart, journey timeline, and panel guidance
① Break-even year & 20-yr energy saving.
② Two futures, side by side.
③ Panel guidance — peak amps vs. capacity.
  • Break-even 2027 — the first year your journey's energy cost comes out ahead. +$138,045 is the saving over the 20-year model.
  • Two futures. Journey $109,133 vs. do nothing $247,178; dotted lines add social cost (+$19,934 avoided).
  • Panel guidance. 41 A today, 78 A peak.
Energy cost only — electricity, gas, gasoline & EV charging. Equipment spend lives in JC.4 · Equipment Replacements (CapEx) in the chart dropdown.

Rates: WhyWatt Conservative (default) for electricity & gas.

WhyWatt? · meet WhyWatt · the cockpit

03 · Meet WhyWatt · 2 of 3

Set up your home

  • Home & timeframe. ZIP, bedrooms and square footage set your California climate zone and find your utilities. Model horizon: 20 yrs.
  • Current Energy Rate. Your utility's actual plan — here PG&E · E-TOU-C, with its 4–9pm peak — and your gas utility's 2025 rate.
  • Projection Method. How prices grow: WhyWatt Conservative (default), Moderate, Stress, or the federal EIA Pacific outlook — chosen separately for electricity and gas.
  • Social & Health. Optional climate and air-quality costs of gas and gasoline.
Setup your home — Home & Simulation Timeframe, Energy & Prices with Current Energy Rate and Projection Method, and Social & Health panels
New: your actual rate plan + how it grows.
WhyWatt? · meet WhyWatt · setup

04 · Meet WhyWatt · 3 of 3

Plan your electrification journey

Your electrification journey — Plan row of nine devices and nine device cards: HVAC, water heater, transportation, cooktop, dryer, baseload, solar, battery, electrical panel
The Plan row — one tap adds a device.
New cards: solar, battery, panel.
  • Nine device cards. Each holds a starting fuel, a swap year, and install / rebate / net cost.
  • HVAC → heat pump, 2027, net $10,500.
  • Water heater → HPWH, 2029, net $2,000.
  • Transportation, cooktop, dryer, baseload — the rest of the home, each on its own timeline.
  • Solar, battery & panel — now full journey cards.
WhyWatt? · meet WhyWatt · journey

05 · Detail views · 1 of 7

Rates & projections

  • One current rate. What you pay today is a fact about your home, so both scenarios share it: PG&E · E-TOU-C and gas at $2.662/therm.
  • Projection = shape, not price. Your current rate is grown by the chosen curve's year-to-year change — no escalation slider needed.
  • Transport fuels. Gasoline $4.50/gal and public EV charging $0.25/kWh, shared across scenarios.
  • What-if. Tick Compare two scenarios (A vs B) to test a second projection side by side.
Rate Scenarios detail — current energy rate shared by scenarios A and B, and projection method buttons for electricity and gas
Transport fuels — gasoline and external EV charging prices and yearly change, plus Compare two scenarios toggle
WhyWatt? · detail views · rates

06 · Detail views · 2 of 7

HVAC — heating & cooling

HVAC detail — gas furnace 336 therms/yr vs. 3-ton heat pump 2,555 kWh/yr, with electrical load and costs

Every card opens a detail page. Gas furnace today, heat pump planned for 2027.

  • Side by side. Furnace ~336 therms/yr vs. heat pump ~2,555 kWh/yr (heating + cooling).
  • Real parameters. AFUE 0.8 → COP 3.5, SEER 22, furnace age & life.
  • Sizing & wiring. 3.0 ton unit on 240 V · 30 A; design load for CZ4 shown alongside.
  • Adds cooling. "Has central AC" is off — the heat pump brings AC the home never had.
WhyWatt? · detail views · hvac

07 · Detail views · 3 of 7

Water heater

  • Side by side. Gas ~163 therms/yr vs. heat-pump water heater ~889 kWh/yr.
  • Your hot water. 65 gal/day, 120 °F setpoint; cold-inlet temperature comes from your climate zone.
  • Efficiency. UEF 0.65 → 3.5, installed in conditioned or unconditioned space.
  • Wiring. The HPWH needs a 240 V · 15 A breaker.
Water heater detail — gas water heater 163 therms/yr vs. heat pump water heater 889 kWh/yr
WhyWatt? · detail views · water heater

08 · Detail views · 4 of 7

Transportation — EV + charger

Transportation detail — do nothing gasoline car vs. your journey EV
Transportation detail — L2 charger hardware, 32 A, net $800
  • Do nothing. Keep the gas car: ~429 gal/yr at 28 MPG.
  • Your journey. EV from 2026: ~3,896 kWh/yr — 85% charged at home, the rest at public rates.
  • Charger. L2 at 32 A · 7.7 kW, net $800 — hardware only; the car itself isn't modeled.
WhyWatt? · detail views · transportation

09 · Detail views · 5 of 7

Cooktop & dryer

  • Cooktop. Gas ~36 therms/yr → induction ~655 kWh/yr, from meals per week. Needs 240 V · 40 A.
  • Dryer. Gas ~57 therms/yr → heat-pump dryer ~468 kWh/yr, from loads per week. Needs 240 V · 30 A.
  • Age & life. Each tracks when the old unit wears out — that sets the like-for-like replacement under do nothing.
Cooktop detail — gas 36 therms/yr vs. induction 655 kWh/yr
Dryer detail — gas 57 therms/yr vs. heat pump dryer 468 kWh/yr
WhyWatt? · detail views · cooktop & dryer

10 · Detail views · 6 of 7

Solar + battery

Solar detail — 15 panels, 6.3 kW, NEM 3.0, 10,358 kWh gross production, covers 80% of home need
Battery detail — 13.5 kWh usable, supplies 3,978 kWh in year 20, self-powered all year
  • Solar from your ZIP. 15 panels · 6.3 kW produce 10,358 kWh a year (PVWatts).
  • NEM 3.0. Exports earn the hourly avoided-cost value — little at midday, far more in the evening.
  • Covers 80% of the home's year-20 need; only 2,002 kWh is exported.
  • Battery. Powerwall 3 defaults (13.5 kWh). Each month it runs Self-powered or Cost-saving, whichever saves more — here it supplies 3,978 kWh.
WhyWatt? · detail views · solar + battery

11 · Detail views · 7 of 7

Electrical panel

  • When amps run out. An L2 charger or heat pump often pushes an older 100 A panel past its limit.
  • Code-based estimate. Peak load follows NEC 220.82 (optional method) — the Bay Area permit default.
  • Plan the upgrade. 200 A in the year you need it, net $3,000 — pure capital, no energy saving.
  • Ties to the cockpit. Panel guidance flags when your plan exceeds capacity.
Electrical panel upgrade detail — 100 A to 200 A, NEC 220.82 optional load calculation, $3,000
WhyWatt? · detail views · panel
Scenario 01

Replace-on-failure · 1 of 2

The Technophile

Researches carefully, replaces on failure, and isn't especially price-sensitive. Goes heat pump for both heating and hot water.

  • The plan. HVAC → heat pump 2027, water heater → HPWH 2029. Everything else stays gas.
  • The rates. Electricity on WhyWatt Conservative, gas on the federal EIA Pacific outlook.
  • Energy only. Social & health costs are left off — a pure dollars-and-cents view.
Technophile setup — PG&E E-TOU-C, electricity Conservative, gas EIA Pacific, social and health costs off
Conservative ⚡ · EIA Pacific 🔥
Social & health: off.
WhyWatt? · scenario 01 · setup
Scenario 01

Replace-on-failure · 2 of 2

The Technophile — the verdict

Technophile result — break-even 2027, +$9,071 over 20 years, $86,175 vs. $95,246, peak 78 A approaching panel limit
  • Modest, but positive. Break-even in 2027; +$9,071 ahead on energy over 20 years ($86,175 vs. $95,246).
  • Check the capital side. $12,500 net for two heat pumps vs. like-for-like replacements — see JC.4 (CapEx).
  • You're buying cooling, too. No AC today — part of the spend buys comfort.
  • Panel headroom. Peak 78 A — near the limit before any EV.
Same devices as the cockpit — only the gas projection differs (EIA Pacific here, Conservative there): +$138k becomes +$9k.
WhyWatt? · scenario 01 · verdict
Scenario 02

Appliance refresh + EV · 1 of 2

The EV Family

EV Family setup — social and health costs on: climate $1.07/therm, air quality $1.23/therm, gasoline climate $1.69/gal and health $0.75/gal
Social & health: all on.

An EV-owning, socially-minded household — adds a charger, moves every appliance off gas, and layers in solar + battery.

  • Counts the hidden cost of gas. Climate (SC-CO₂ + SC-CH₄) $1.07/therm and air quality $1.23/therm.
  • …and of gasoline. Climate $1.69/gal and health $0.75/gal.
  • Same rates as the Technophile. Electricity Conservative, gas EIA Pacific — so the difference is the plan.
WhyWatt? · scenario 02 · setup
Scenario 02

Appliance refresh + EV · 2 of 2

The EV Family — the verdict

  • Big energy saving. Break-even 2025; +$71,415 over 20 years ($23,831 vs. $95,246).
  • Strong social return. +$42,433 avoided climate & health cost.
  • The panel is the constraint. Peak 119 A exceeds the 100 A panel — the plan adds a 200 A upgrade ($3,000). Guidance still warns: it measures today's panel.
  • Capital is real. ≈ $49,000 planned, $30,000 of it solar + battery — see JC.4 (CapEx).
EV Family result — break-even 2025, +$71,415 energy saving, +$42,433 social cost avoided, peak 119 A exceeds 100 A panel, panel upgrade planned
119 A peak exceeds the 100 A panel.
200 A upgrade planned (EP).
WhyWatt? · scenario 02 · verdict