Energy Star Savings Calculator Formula

Understand the math behind the energy star savings calculator. Each variable explained with a worked example.

Use the Energy Star Savings Calculator

Formulas Used

Annual Savings

annual_save = annual_savings

Lifetime Savings

lifetime_save = annual_savings * lifespan

Energy Reduction

energy_reduction = saved_kwh / standard_kwh * 100

CO2 Saved per Year

co2_saved = saved_kwh * 0.92 / 2204.6

Variables

VariableDescriptionDefault
standard_kwhStandard Model Annual kWh(kWh)500
energystar_kwhEnergy Star Model Annual kWh(kWh)350
rate_per_kwhElectricity Rate(USD/kWh)0.15
lifespanAppliance Lifespan(years)12
saved_kwhDerived value= standard_kwh - energystar_kwhcalculated
annual_savingsDerived value= saved_kwh * rate_per_kwhcalculated

How It Works

How to Calculate Energy Star Savings

Energy Star certified products meet strict energy efficiency guidelines set by the EPA.

Formula

Annual Savings = (Standard kWh - Energy Star kWh) * Rate

Lifetime Savings = Annual Savings * Lifespan

Typical Energy Star Savings

  • Refrigerator: 9-10% less energy
  • Clothes washer: 25% less energy
  • Dishwasher: 12% less energy
  • Air conditioner: 15% less energy

    • Worked Example

    An Energy Star refrigerator using 350 kWh/year vs standard at 500 kWh/year over 12 years at $0.15/kWh.

    standard_kwh = 500energystar_kwh = 350rate_per_kwh = 0.15lifespan = 12
    1. 01Energy saved: 500 - 350 = 150 kWh/year
    2. 02Annual savings: 150 * $0.15 = $22.50
    3. 03Lifetime savings: $22.50 * 12 = $270
    4. 04Energy reduction: 150 / 500 * 100 = 30%

    Ready to run the numbers?

    Open Energy Star Savings Calculator