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%

    Frequently Asked Questions

    What does Energy Star mean?

    Energy Star is a government-backed certification indicating a product meets strict energy efficiency standards. Products must be 15-30% more efficient than non-certified models.

    Is the Energy Star premium worth it?

    Usually yes. The extra upfront cost of $50-200 is typically recovered in 1-3 years through energy savings, and you continue saving for the remaining appliance life.

    Which Energy Star appliances save the most?

    HVAC systems, water heaters, and clothes washers offer the largest absolute savings due to high energy use. Percentage-wise, LED bulbs and clothes washers see the biggest efficiency gains.

    Ready to run the numbers?

    Open Energy Star Savings Calculator