VFD Energy Savings Estimator

Variable-speed pumping drops energy consumption roughly with the cube of flow reduction (affinity law). This tool estimates the annual kWh and dollar savings when you pair a BBP vertical inline pump with a VFD instead of throttling a fixed-speed motor.

Motor Size (HP)

Motor Efficiency (%)

IE3 class ≈ 93%; IE4 ≈ 95%

Operating Hours / Year

24/7 = 8,760; HVAC seasonal = 3,500 – 5,000

Avg. Flow Demand (% of Design)

Part-load buildings run 50 – 75%; process loops 70 – 90%

Electricity Rate ($/kWh)

Baseline (Fixed-Speed) Strategy

Both run at near-full motor load regardless of demand

Estimated Annual Savings with VFD

Baseline (fixed-speed) kWh/year—

VFD-driven kWh/year—

Energy saved—

Baseline annual cost—

VFD-driven annual cost—

Estimated Annual Savings —

Estimate based on the pump affinity law (flow reduction → cube of power). Actual savings depend on system curve, VFD drive efficiency, motor load factor, and part-load duration distribution. Use this figure as an order-of-magnitude check, not a guaranteed saving. The IEA EBC Annex 61 deep-energy-retrofit case studies report 15 – 35% building-energy reductions when VFD-driven vertical inline pumps are paired with heat-pump and chilled-water loop upgrades.

Ask for a case-specific TCO analysis based on your building load profile