{"openapi":"3.1.0","info":{"title":"Home Energy Calculators","version":"1.0.0","description":"Home energy math for agents: bills, appliance loads, solar sizing, heat loss, HVAC load checks, insulation, water heating, EV charging and fuel cost. One call, one computed answer, no accounts or API keys. Machine-payable over x402.","x-guidance":"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. Use /household-load to total a list of appliances into kWh and cost, /bill-estimate for a tiered electricity bill, /solar-sizing for panel system size and payback, /heat-loss for building heat loss in BTU/h, /hvac-sizing for room air-conditioner sizing and an oversizing check, /insulation-r-value for wall and roof assemblies with framing, /water-heater for recovery rate and heat-up time, /ev-charging for charge time, cost and circuit limits, and /heating-cost-compare for cost per unit of delivered heat across electricity, gas, propane, oil and heat pumps. Each paid GET returns a computed verdict with the reasons, the source and what was NOT checked. A verdict of UNVERIFIED means a lookup failed: treat it as unknown. No account or key: pay per call in USDC over x402."},"servers":[{"url":"https://home-energy-calc.x402tookit.com"}],"paths":{"/bill-estimate":{"get":{"operationId":"bill_estimate","summary":"Estimate a monthly electricity bill from kWh with block-tier rates, a fixed monthly charge and a tax or fee percentage.","description":"Estimate a monthly electricity bill from kWh with block-tier rates, a fixed monthly charge and a tax or fee percentage.","tags":["energy","electricity","bill","rates","calculator"],"parameters":[{"name":"kwh","in":"query","required":true,"description":"Energy used in the month, kWh (0 to 100000)","schema":{"type":"number"}},{"name":"tiers","in":"query","required":true,"description":"Rate blocks kWh@rate separated by semicolons, last block 'rest@rate', for example '500@0.12; 500@0.15; rest@0.20'; a single 'rest@0.14' is a flat rate","schema":{"type":"string"}},{"name":"fixedCharge","in":"query","required":false,"description":"Fixed monthly service charge (default 0)","schema":{"type":"number"}},{"name":"taxPercent","in":"query","required":false,"description":"Taxes and percentage fees on the total, 0 to 50 (default 0)","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"kwh":{"type":["null","number"]},"energyCharge":{"type":["null","number"]},"fixedCharge":{"type":["null","number"]},"subtotal":{"type":["null","number"]},"taxes":{"type":["null","number"]},"total":{"type":["null","number"]},"averagePricePerKwh":{"type":["null","number"]},"tierBreakdown":{"type":["array","null"],"items":{"type":"object","properties":{"kwh":{"type":["null","number"]},"rate":{"type":["null","number"]},"cost":{"type":["null","number"]}}}},"unbilledKwh":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"COMPUTED","summary":"800 kWh costs 124.2: energy 105 + fixed 10 + 8% tax 9.2.","reasons":["Energy charge = kWh in each block x that block's rate, then fixed charge, then tax on the sum.","Average price 0.1553 per kWh including fixed charge and tax; marginal (next kWh) price 0.162."],"kwh":800,"energyCharge":105,"fixedCharge":10,"subtotal":115,"taxes":9.2,"total":124.2,"averagePricePerKwh":0.15525,"tierBreakdown":[{"kwh":500,"rate":0.12,"cost":60},{"kwh":300,"rate":0.15,"cost":45}],"unbilledKwh":0,"degraded":false,"notChecked":["time-of-use, demand and seasonal rates, riders, fuel-cost adjustments and credits (enter their effect in the tiers if you know it)","your utility's actual billing rules, rounding and proration","…2 more"],"source":"computed locally","asOf":"2026-10-11T14:31:35.125Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/bill-estimate"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/bill-estimate"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/bill-estimate"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/bill-estimate"}}]}}},"/ev-charging":{"get":{"operationId":"ev_charging","summary":"Electric vehicle charging time, cost and range added from battery size, charge levels, charger power or circuit, and price.","description":"Electric vehicle charging time, cost and range added from battery size, charge levels, charger power or circuit, and price.","tags":["energy","ev","charging","electric-vehicle","calculator"],"parameters":[{"name":"batteryKwh","in":"query","required":true,"description":"Usable battery capacity in kWh, 5 to 300","schema":{"type":"number"}},{"name":"startPercent","in":"query","required":true,"description":"State of charge at the start, 0 to 99","schema":{"type":"number"}},{"name":"endPercent","in":"query","required":true,"description":"State of charge wanted, 1 to 100 (above the start)","schema":{"type":"number"}},{"name":"chargerKw","in":"query","required":false,"description":"Charger power in kW delivered to the car's charger, 0.5 to 400 (or use breakerAmps, or level)","schema":{"type":"number"}},{"name":"breakerAmps","in":"query","required":false,"description":"Or the circuit breaker size in amps; a continuous load may use 80% of it (voltage from volts, default 240)","schema":{"type":"number"}},{"name":"volts","in":"query","required":false,"description":"Circuit voltage with breakerAmps, 100 to 480 (default 240)","schema":{"type":"number"}},{"name":"level","in":"query","required":false,"description":"Or level1 (120 V, 12 A) or level2 (240 V, 32 A)","schema":{"type":"string"}},{"name":"chargingEfficiency","in":"query","required":false,"description":"Wall-to-battery efficiency 0.7 to 1 (default 0.90 for AC charging)","schema":{"type":"number"}},{"name":"pricePerKwh","in":"query","required":false,"description":"Electricity price per kWh, for cost","schema":{"type":"number"}},{"name":"milesPerKwh","in":"query","required":false,"description":"Vehicle efficiency in miles per kWh, 0.5 to 8, for range added","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"batteryKwh":{"type":["null","number"]},"startPercent":{"type":["null","number"]},"endPercent":{"type":["null","number"]},"energyAddedToBatteryKwh":{"type":["null","number"]},"energyFromWallKwh":{"type":["null","number"]},"lossKwh":{"type":["null","number"]},"chargerKw":{"type":["null","number"]},"chargerSource":{"type":["null","string"]},"chargingEfficiency":{"type":["null","number"]},"hours":{"type":["null","number"]},"minutes":{"type":["null","number"]},"circuitAmps":{"type":["null","number"]},"circuitVolts":{"type":["null","number"]},"cost":{"type":["null","number"]},"milesAdded":{"type":["null","number"]},"costPerMile":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"COMPUTED","summary":"Charging 20% to 80% of a 60 kWh battery adds 36 kWh (40 kWh from the wall at 90% efficiency); at 7.68 kW (40 A breaker x 80% continuous = 32 A at 240 V) that takes about 5.2 hours. 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Not financial, legal or investment advice; provided as is. Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/ev-charging"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/ev-charging"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/ev-charging"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/ev-charging"}}]}}},"/heat-loss":{"get":{"operationId":"heat_loss","summary":"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.","description":"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.","tags":["energy","heat-loss","hvac","insulation","calculator"],"parameters":[{"name":"surfaces","in":"query","required":true,"description":"Lines name:areaSqFt:Rvalue separated by semicolons, for example 'walls:1000:13; windows:150:3; roof:1000:38'","schema":{"type":"string"}},{"name":"indoorF","in":"query","required":true,"description":"Indoor temperature in F, 40 to 90","schema":{"type":"number"}},{"name":"outdoorF","in":"query","required":true,"description":"Design outdoor temperature in F, -60 to 130","schema":{"type":"number"}},{"name":"volumeCuFt","in":"query","required":false,"description":"Heated volume in cubic feet, for air leakage (with airChangesPerHour)","schema":{"type":"number"}},{"name":"airChangesPerHour","in":"query","required":false,"description":"Air changes per hour, 0.05 to 5 (a tight house is about 0.2 to 0.5)","schema":{"type":"number"}},{"name":"heatingDegreeDaysF","in":"query","required":false,"description":"Heating degree-days (base 65 F) per year, for annual energy","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"deltaTF":{"type":["null","number"]},"conductionBtuPerHour":{"type":["null","number"]},"infiltrationBtuPerHour":{"type":["null","number"]},"infiltrationCfm":{"type":["null","number"]},"totalBtuPerHour":{"type":["null","number"]},"totalWatts":{"type":["null","number"]},"totalKw":{"type":["null","number"]},"totalTons":{"type":["null","number"]},"totalUaBtuPerHourF":{"type":["null","number"]},"surfaces":{"type":["array","null"],"items":{"type":"object","properties":{"name":{"type":["null","string"]},"areaSqFt":{"type":["null","number"]},"rValue":{"type":["null","number"]},"uValue":{"type":["null","number"]},"ua":{"type":["null","number"]},"btuPerHour":{"type":["null","number"]},"sharePercent":{"type":["null","number"]}}}},"infiltrationSharePercent":{"type":["null","number"]},"annualHeatNeedMMBtu":{"type":["null","number"]},"annualHeatNeedKwh":{"type":["null","number"]},"annualHeatNeedTherms":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"COMPUTED","summary":"At a 40 F difference the building loses about 15435 BTU/h (4523 W): 8235 through surfaces and 7200 from air leakage (166.7 CFM). Over 5000 degree-days that is about 46.3 MMBtu of heat a year.","reasons":["Conduction = area x temperature difference / R; infiltration = 1.08 x CFM x temperature difference, where CFM = air changes per hour x volume / 60.","Largest loss: walls (19.9%).","…1 more"],"deltaTF":40,"conductionBtuPerHour":8234.8,"infiltrationBtuPerHour":7200,"infiltrationCfm":166.7,"totalBtuPerHour":15434.8,"totalWatts":4523,"totalKw":4.52,"totalTons":1.29,"totalUaBtuPerHourF":385.87,"surfaces":[{"name":"walls","areaSqFt":1000,"rValue":13,"uValue":0.0769,"ua":76.923,"btuPerHour":3076.9,"sharePercent":19.9},{"name":"windows","areaSqFt":150,"rValue":3,"uValue":0.3333,"ua":50,"btuPerHour":2000,"sharePercent":13}],"infiltrationSharePercent":46.6,"annualHeatNeedMMBtu":46.3,"annualHeatNeedKwh":13571,"annualHeatNeedTherms":463,"degraded":false,"notChecked":["thermal bridging through studs, which lowers a wall's effective R-value (see /insulation-r-value)","solar gains, internal gains, ground contact and unheated-space buffers","…2 more"],"source":"computed locally","asOf":"2026-10-11T14:31:35.646Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/heat-loss"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/heat-loss"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/heat-loss"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://home-energy-calc.x402tookit.com/heat-loss"}}]}}},"/heating-cost-compare":{"get":{"operationId":"heating_cost_compare","summary":"Cost per million BTU of delivered heat for resistance, heat pump, gas, propane and heating oil furnaces, from your prices.","description":"Cost per million BTU of delivered heat for resistance, heat pump, gas, propane and heating oil furnaces, from your prices.","tags":["energy","heating","heat-pump","fuel-cost","calculator"],"parameters":[{"name":"electricityPerKwh","in":"query","required":false,"description":"Electricity price per kWh (gives resistance and heat pump)","schema":{"type":"number"}},{"name":"gasPerTherm","in":"query","required":false,"description":"Natural gas price per therm (1 therm = 100,000 BTU)","schema":{"type":"number"}},{"name":"propanePerGallon","in":"query","required":false,"description":"Propane price per gallon (91,452 BTU/gal)","schema":{"type":"number"}},{"name":"oilPerGallon","in":"query","required":false,"description":"Heating oil price per gallon (137,381 BTU/gal)","schema":{"type":"number"}},{"name":"heatPumpCop","in":"query","required":false,"description":"Seasonal heat pump COP, 1.5 to 6 (default 3)","schema":{"type":"number"}},{"name":"gasAfue","in":"query","required":false,"description":"Gas furnace efficiency 0.5 to 0.99 (default 0.95)","schema":{"type":"number"}},{"name":"propaneAfue","in":"query","required":false,"description":"Propane furnace efficiency 0.5 to 0.99 (default 0.95)","schema":{"type":"number"}},{"name":"oilAfue","in":"query","required":false,"description":"Oil furnace efficiency 0.5 to 0.99 (default 0.85)","schema":{"type":"number"}},{"name":"annualHeatMMBtu","in":"query","required":false,"description":"Yearly heat your home needs in million BTU (see /heat-loss), for yearly cost","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"systemsRankedCheapestFirst":{"type":["array","null"],"items":{"type":"object","properties":{"system":{"type":["null","string"]},"assumedEfficiency":{"type":["null","number"]},"costPerMMBtuDelivered":{"type":["null","number"]},"note":{"type":["null","string"]},"relativeToCheapest":{"type":["null","number"]},"yearlyCost":{"type":["null","number"]}}}},"heatPumpBreakEvenElectricityPerKwhVsGas":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"COMPUTED","summary":"Cheapest delivered heat: heat pump at 15.63 per million BTU (938 a year for 60 MMBtu); most expensive: electric resistance at 46.89.","reasons":["Cost per delivered MMBtu = fuel price per MMBtu of energy content / efficiency (or COP).","Heat contents: 1 kWh = 3,412 BTU; 1 therm = 100,000 BTU; propane 91,452 BTU/gal and heating oil 137,381 BTU/gal (EIA). A heat pump at COP 3 beats the gas furnace while electricity costs under 0.1616 p…"],"systemsRankedCheapestFirst":[{"system":"heat pump","assumedEfficiency":3,"costPerMMBtuDelivered":15.63,"note":"seasonal COP 3","relativeToCheapest":1,"yearlyCost":938},{"system":"natural gas furnace","assumedEfficiency":0.95,"costPerMMBtuDelivered":15.79,"note":"AFUE 0.95","relativeToCheapest":1.01,"yearlyCost":947}],"heatPumpBreakEvenElectricityPerKwhVsGas":0.1616,"degraded":false,"notChecked":["equipment cost, maintenance, installation and duct losses","heat pump performance falling in very cold weather: the COP is a seasonal average you must choose for your climate","…2 more"],"source":"computed locally","asOf":"2026-10-11T14:31:35.911Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. 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Largest: refrigerator (37.3%).","reasons":["kWh = watts x hours per day x quantity x days per year / 1000; cost = kWh x price.","Appliances are listed largest first."],"totalKwhPerYear":1175.3,"totalKwhPerMonth":97.94,"totalKwhPerDay":3.22,"totalCostPerYear":188.05,"totalCostPerMonth":15.67,"averageWatts":134.2,"appliances":[{"name":"refrigerator","watts":150,"hoursPerDay":8,"quantity":1,"daysPerYear":365,"kwhPerYear":438,"kwhPerMonth":36.5,"costPerYear":70.08,"sharePercent":37.3},{"name":"standby (always on)","watts":30,"hoursPerDay":24,"quantity":1,"daysPerYear":365,"kwhPerYear":262.8,"kwhPerMonth":21.9,"costPerYear":42.05,"sharePercent":22.4}],"degraded":false,"notChecked":["real power draw: nameplate watts overstate what most devices use, and motors, compressors and heaters cycle (enter an average hours-on figure, such as a fridge's compressor run time of about a third o…","time-of-use or tiered rates and demand charges (see /bill-estimate)","…2 more"],"source":"computed locally","asOf":"2026-10-11T14:31:36.172Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. 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