# Home Energy Calculators

Home energy math for agents: bills, appliance loads, solar sizing, heat loss, HVAC load checks, insulation, water heating, EV charging and fuel cost.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://home-energy-calc.x402tookit.com/openapi.json
- x402 manifest: https://home-energy-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://home-energy-calc.x402tookit.com/catalog
- Health (free): https://home-energy-calc.x402tookit.com/health
- Uptime (free): https://home-energy-calc.x402tookit.com/uptime

## Endpoints (9)

### GET /bill-estimate — $0.02
Estimate a monthly electricity bill from kWh with block-tier rates, a fixed monthly charge and a tax or fee percentage.
Params: kwh: number, tiers: string, fixedCharge?: number, taxPercent?: number
Example: https://home-energy-calc.x402tookit.com/bill-estimate?kwh=800&tiers=500%400.12%3B+rest%400.15&fixedCharge=10&taxPercent=8

### GET /ev-charging — $0.02
Electric vehicle charging time, cost and range added from battery size, charge levels, charger power or circuit, and price.
Params: batteryKwh: number, startPercent: number, endPercent: number, chargerKw?: number, breakerAmps?: number, volts?: number, level?: string, chargingEfficiency?: number, pricePerKwh?: number, milesPerKwh?: number
Example: https://home-energy-calc.x402tookit.com/ev-charging?batteryKwh=60&startPercent=20&endPercent=80&breakerAmps=40&pricePerKwh=0.16&milesPerKwh=3.5

### GET /heat-loss — $0.02
Heat loss of a building in BTU/h and watts from surface areas and R-values plus air leakage, and yearly energy from degree-days.
Params: surfaces: string, indoorF: number, outdoorF: number, volumeCuFt?: number, airChangesPerHour?: number, heatingDegreeDaysF?: number
Example: https://home-energy-calc.x402tookit.com/heat-loss?surfaces=walls%3A1000%3A13%3B+windows%3A150%3A3%3B+roof%3A1000%3A38%3B+floor%3A1000%3A19&indoorF=70&outdoorF=30&volumeCuFt=20000&airChangesPerHour=0.5&heatingDegreeDaysF=5000

### GET /heating-cost-compare — $0.02
Cost per million BTU of delivered heat for resistance, heat pump, gas, propane and heating oil furnaces, from your prices.
Params: electricityPerKwh?: number, gasPerTherm?: number, propanePerGallon?: number, oilPerGallon?: number, heatPumpCop?: number, gasAfue?: number, propaneAfue?: number, oilAfue?: number, annualHeatMMBtu?: number
Example: https://home-energy-calc.x402tookit.com/heating-cost-compare?electricityPerKwh=0.16&gasPerTherm=1.5&propanePerGallon=3.2&oilPerGallon=4&annualHeatMMBtu=60

### GET /household-load — $0.02
Total a list of appliances (watts, hours a day, quantity) into kWh and cost per day, month and year, with each one's share.
Params: appliances: string, pricePerKwh: number, standbyWatts?: number
Example: https://home-energy-calc.x402tookit.com/household-load?appliances=refrigerator%3A150%3A8%3B+led+bulb%3A9%3A5%3A12%3B+television%3A100%3A4%3B+laptop%3A60%3A6&pricePerKwh=0.16&standbyWatts=30

### GET /hvac-sizing — $0.02
Room air-conditioner BTU from floor area (ENERGY STAR chart), tons, and an under- or over-sizing check against a load.
Params: roomSqFt?: number, loadBtuH?: number, equipmentBtuH?: number, equipmentTons?: number, kind?: string
Example: https://home-energy-calc.x402tookit.com/hvac-sizing?roomSqFt=320

### GET /insulation-r-value — $0.02
R-value and U-factor of a wall or roof assembly from layers and thickness, with a framing-fraction correction and heat flow.
Params: layers: string, cavity?: string, framingDepthInches?: number, framingFractionPercent?: number, includeAirFilms?: boolean, areaSqFt?: number, deltaTF?: number
Example: https://home-energy-calc.x402tookit.com/insulation-r-value?layers=drywall%3A0.5%3B+sheathing%3A0.6r%3B+siding%3A0.6r&cavity=fiberglass+batt%3A3.5&framingFractionPercent=25&includeAirFilms=true&areaSqFt=1000&deltaTF=40

### GET /solar-sizing — $0.02
Size a rooftop solar system from annual kWh and peak sun hours: kW, panel count, yearly output, savings and simple payback.
Params: annualKwh: number, peakSunHours: number, panelWatts?: number, offsetPercent?: number, systemLossPercent?: number, pricePerKwh?: number, costPerWatt?: number, incentivePercent?: number
Example: https://home-energy-calc.x402tookit.com/solar-sizing?annualKwh=10000&peakSunHours=4.5&panelWatts=400&pricePerKwh=0.16&costPerWatt=3

### GET /water-heater — $0.02
Water heater recovery rate (gallons an hour), tank heat-up time and energy cost from input power, efficiency and rise.
Params: fuel: string, inputPower: number, riseF: number, efficiency?: number, tankGallons?: number, pricePerKwh?: number, pricePerTherm?: number
Example: https://home-energy-calc.x402tookit.com/water-heater?fuel=electric&inputPower=4.5&riseF=70&tankGallons=50&pricePerKwh=0.16

## Terms

Home energy calculators using standard physics, published conversion factors (EIA, NREL PVWatts defaults, ENERGY STAR) and your inputs, provided as is. Results are estimates for planning, not engineering design: heating, cooling, solar and electrical work needs a qualified contractor, a Manual J load calculation and local code review. Utility rates, climate and equipment performance vary.