VSD Compressor Savings Calculator

Energy savings from variable speed drive vs load/unload.

Compressor HP

Average load (%)

Electricity rate ($/kWh)

Operating hours/year

Motor efficiency (%)

Tab to move between fields

Annual energy savings ($)

$2,554.24

≈ 20 pairs of sneakers

Savings (%)10

Load/unload annual cost ($)$25,542.39

VSD annual cost ($)$22,988.15

Annual kWh savings25,542

Simple payback (years)3.7

CO₂ reduction (lbs/yr)21,839

How to Use This Calculator

Enter the current fixed-speed compressor horsepower and motor efficiency.
Set the average load factor (percentage of full-load operation).
Input your electricity rate and annual operating hours.
Enter the VSD compressor cost and expected savings percentage from variable-speed operation.
Review annual energy savings, simple payback, and 5-year NPV to justify the capital investment.

How the result changes with Average load (%)

Compressor HP: Nameplate horsepower of the existing or proposed compressor.
Average load (%): Average percentage of full capacity the compressor delivers. VSD savings are greatest at 40–70% load.
Electricity rate ($/kWh): Blended electricity cost per kilowatt-hour.
Operating hours/year: Annual hours the compressor runs.
Motor efficiency (%): Motor nameplate efficiency.

Annual energy savings ($): Yearly electricity cost savings from switching to VSD.
Savings (%): Percentage reduction in energy cost.
Load/unload annual cost ($): Current annual energy cost with fixed-speed load/unload control.
VSD annual cost ($): Projected annual energy cost with VSD compressor.
Annual kWh savings: Kilowatt-hours saved per year.
Simple payback (years): Estimated years to recover VSD premium cost through energy savings.
CO₂ reduction (lbs/yr): Annual CO₂ emission reduction from energy savings.

Identify Input Parameters
4 parameters
Compressor HP = 75, Average load (%) = 60, Electricity rate ($/kWh) = 0.1, Operating hours/year = 6000 = 5 input(s) provided
Calculate Annual energy savings
Annual energy savings = fixedSpeedAnnualCost - vsdAnnualCost
2554.24 = $2,554.24
Calculate Savings
10 = 10
Calculate Load/unload annual cost
Load/unload annual cost = fixedSpeedAnnualKwh * electricRateKwh
25542.39 = $25,542.39