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Installation of High Efficiency Motors

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Electric motors vary greatly in performance. The selection of energy-efficient motors for HVAC equipment installed in renovation or new construction can result in greatly reduced energy consumption during their operational lifetimes. In converting electrical energy into mechanical energy, motors incur losses in several ways: electrical losses, iron (core) losses, mechanical (friction and windage) losses, and stray losses dependent on design and manufacturing. Energy-efficient motors reduce losses because of their better design, materials, and manufacturing. With proper installation, energy-efficient motors run cooler and thus can have higher service factors and longer bearing and insulation life.

Example of calculating energy cost savings from motor replacement:
Consider replacing a 20 hp motor that operates 80% loaded for 8,760 hours per year where electricity costs 5.5 cents per kilowatt-hour. Assume efficiencies are 0.88 and 0.92 for standard and energy-efficient motors, respectively.

Notice that this does not include savings from reducing electrical power demand.

Standard motor
20 hp x 0.80 x 0.746 kW/hp x 8,760 hr/yr x $0.055 per kWh / 0.88 =
$6,535 per year

Efficient motor:
20 hp x 0.80 x 0.746 kW/hp x 8,760 hr/yr x $0.055 per kWh / 0.92 =
$6,251 per year

Savings:
$6,535 - $6,251 = $ 284 per year