Pump Energy Audit: What Is Measured and How Savings Are Found

Short answer: a pump energy audit measures how much flow and head a pump actually delivers and how much electrical power it draws, then compares the real efficiency with the pump’s design curve. The gap shows how much energy can be saved by trimming, re-sizing, adding a variable-speed drive or replacing the pump.

Why audit pumps?

Pumps often run far from their best-efficiency point because they were oversized, the system has changed or valves are throttled to control flow. That wasted energy is paid for every hour the pump runs, so continuous-duty pumps in HVAC, water supply, cooling and process plants are the first candidates.

What is measured on site

• Flow – with a clamp-on ultrasonic flow meter or existing meters.
• Suction and discharge pressure – to calculate total head.
• Electrical input – voltage, current, power factor and kW with a power analyser.
• Operating pattern – hours, valve positions and how demand varies.

How efficiency is calculated

Hydraulic power (kW) = flow (m³/s) × head (m) × 9.81 × liquid density (kg/m³) ÷ 1000. Pump-set efficiency = hydraulic power ÷ electrical input power. Comparing this with the manufacturer’s curve shows whether the loss is in the pump, the motor or the way the system is controlled.

Typical recommendations

• Replace throttling valves with variable-speed control where demand varies.
• Trim impellers or select a correctly sized pump.
• Replace old, worn pumps with high-efficiency models such as Grundfos E-pumps.
• Switch compressed-air-driven pumps to electric drives — see EODD vs AODD.

What the report contains

Measured data for each pump, present and achievable efficiency, annual energy cost, recommended actions, estimated saving and simple payback. Savings are calculated from your measured data, not assumed.

Book the service: pumping system energy audit · Example: 85%+ energy saving case study.