In industrial facilities, electric motors consume a large part of the electrical energy; therefore, motors are always a priority in energy management. The ISO 50001 Energy Management System is an international framework that enables a facility to systematically measure, monitor and continuously improve its energy performance. However, if you want to use the standard for real savings rather than just to obtain a certificate, you need to place motor efficiency at the center of the work. In this guide we cover conceptually how to build a motor inventory with ISO 50001's baseline and energy performance indicators (EnPI), how to prioritize the transition to efficient motors starting from the most-running and oldest motors, and how to plan the investment in order of payback.

ISO 50001 energy management system and motor efficiency investment prioritization

What Is ISO 50001 and Its Relationship with Motors

ISO 50001 is a management system standard designed for organizations to manage their energy use in a planned way. Its basic logic rests on the principle "you cannot manage what you cannot measure": first energy consumption is measured, a baseline is established, targets are set, and performance is increased with a continuous improvement cycle. Within this cycle, the equipment that consumes the most energy naturally takes the highest priority; in most industrial facilities this equipment is electric motors.

Motor-driven systems such as pumps, fans, compressors, conveyors, mills and mixers are responsible for a significant part of a facility's electricity bill. Therefore, most of the improvements made under ISO 50001 directly or indirectly touch motor efficiency. We covered the importance of building a motor inventory when preparing for an energy efficiency audit in our energy efficiency audit and motor inventory article.

Energy Baseline and EnPI

The two basic concepts of ISO 50001 are the energy baseline (EnB) and the energy performance indicators (EnPI). The baseline is the reference point representing the existing energy consumption state before improvement; all gains are measured against this reference. EnPIs are the indicators used to monitor energy performance; for example, the energy consumed per unit of production or the energy intensity of a particular line.

Why Is the Baseline Important?

Without a solid baseline, it is impossible to prove that the improvement made actually provides savings. The same applies in motor efficiency projects: when you replace a motor with an efficient model, you can only demonstrate the gain by comparing it with the consumption before the change. Therefore, when building the motor inventory, the motors' running hours and load conditions should also be recorded where possible. We explained the methods of measuring and documenting the annual saving of switching to an efficient motor in our measuring annual energy saving article.

Linking EnPI to Motors

Defining EnPIs not only facility-wide but also at the motor-driven system level clarifies which system consumes how much energy. For example, monitoring the energy intensity of a pump station or a fan group makes the efficiency potential of the motors in that system visible. To correctly understand the difference between nameplate efficiency and the real efficiency achieved in the field, our nameplate vs field efficiency difference article will be useful.

Building the Motor Inventory

The first concrete step of improving motor efficiency under ISO 50001 is to build an inventory of all the motors in the facility. This inventory should include each motor's power, speed, efficiency class, age, running hours, load condition and the application it drives. In most facilities the actual number and condition of motors is not clearly known; the inventory work provides this visibility.

When building the inventory, it is important to read the motors' nameplate information correctly; the power, speed, efficiency class and duty type on the nameplate are the basis for evaluating the motor's improvement potential. We explained how to read an IE3 motor nameplate in our reading the IE3 motor nameplate article. When the inventory is complete, it becomes clear which motors are old, low-efficiency or rewound many times; these motors are the first candidates for prioritization.

Facility motor inventory and efficient motor transition prioritization plan

Prioritization: The Most-Running and Oldest Motors

Replacing all motors at once is neither possible nor necessary for most businesses. The smart approach is to start with the motors that have the highest saving potential. Two criteria stand out in prioritization: the motor's running hours and its efficiency condition.

Priority by Running Hours

The higher a motor's annual running hours, the greater the saving an efficiency improvement will bring. A continuously running motor (for example, three shifts) provides a much faster payback than an occasionally running motor. Therefore, the first place in prioritization belongs to the most-running motors. We covered the ways to manage a motor fleet in three-shift facilities in our motor fleet management in three-shift facilities article.

Priority by Age and Efficiency Condition

The oldest and lowest-efficiency motors provide the largest efficiency jump when replaced. Motors that have been rewound many times and are in an old efficiency class fall into this category. Motors with high running hours and a low efficiency class form the top corner of the prioritization matrix; these motors are the target of the first investment wave. You can examine the logic of scaling the transition to efficient motors from a single motor to the whole facility in our single motor to fleet saving article.

Investment Plan in Order of Payback

After prioritization, ranking the investment by payback period ensures the most efficient use of resources. A plan that starts with the fastest-paying motors and progresses toward motors with longer payback periods both protects cash flow and makes the saving visible in the shortest time. In this approach, the saving achieved in the first wave can partially finance the investment of subsequent waves.

When evaluating the payback period, you should look not only at the motor price but at the total cost of ownership (TCO); because the real gain is in the lifetime energy cost. We explained how to calculate TCO in our total cost of ownership article. To evaluate the investment decision between IE3 and IE4 with payback logic, our IE3 vs IE4 investment article provides guidance. We also covered the additional saving provided together with a variable frequency drive in pump and fan applications in our high-efficiency motor and variable frequency drive article.

Non-Motor Measures: Looking at the System as a Whole

When addressing motor efficiency under ISO 50001, you need to evaluate the motor not on its own but as a part of the system it drives. A pump or fan system is affected not only by the motor's efficiency class, but also by the system's correct sizing, speed control and mechanical losses. For example, instead of throttling an oversized pump with a control valve, adjusting its speed with a variable frequency drive provides far more energy saving.

Therefore, when planning a motor change, looking at the whole system and, where possible, addressing speed control, correct sizing and mechanical improvements together multiplies the gain. We covered the right motor and control selection in variable-speed applications in our VFD with asynchronous motor article, and the saving approach that starts from a single motor and spreads to the whole facility should be evaluated together with the inventory and prioritization logic. We covered the role of efficient motors in reducing the carbon footprint in our carbon footprint article.

Documentation, Monitoring and Reporting

The sustainability of ISO 50001 rests on regular monitoring and reporting. In motor efficiency projects, the gain of each change must be measured, recorded and reported to management. This documentation both provides the evidence the standard requires and forms the justification for the next investment wave. A well-documented saving makes it easier for management to approve new investments.

In the monitoring process, the EnPI indicators are reviewed at regular intervals and compared with the targets. If the expected improvement is not seen in an indicator, the root cause is investigated; whether the problem is in the motor, in another component of the system, or in the measurement method is determined. This disciplined monitoring turns energy management from a one-time project into a continuous process. The methods of measuring and documenting the annual saving form the basis of this reporting discipline.

The Continuous Improvement Cycle

The essence of ISO 50001 is not a one-time project but a continuous improvement cycle (Plan-Do-Check-Act). This cycle also applies in motor efficiency projects: one wave of motors is replaced, the gain is measured and documented, then the next priority group is addressed. In each cycle, the motor inventory is updated and new priorities are set.

For this cycle to be sustainable, it is important to preserve the efficiency class of newly purchased motors and to size them correctly. An oversized or undersized motor loses the efficiency advantage from the start. We covered the effect of correct sizing on energy performance in our motor load ratio and correct sizing article. You can examine the effect of an efficient motor on the power factor and reactive penalty in our power factor and reactive penalty article. For stock and fast supply in new motor procurement, you can visit our efficient electric motors category and our home page.

Frequently Asked Questions

Is replacing motors mandatory for ISO 50001?

The standard does not make a specific equipment change mandatory; however, it requires continuous energy performance improvement. Because motors consume the largest part of the energy, the transition to efficient motors is one of the most effective and fastest-paying improvements in most facilities. So it is not mandatory but usually the most sensible step.

Which motors should I start prioritizing with?

It is best to start with the most-running (high annual running hours) and the oldest/lowest-efficiency motors. The motors where these two criteria intersect carry the highest saving potential and provide the fastest payback. Therefore, it is wise to mark these motors in the inventory and take them into the first investment wave.

How do I prove savings without a baseline?

You cannot. Without a solid baseline, it is impossible to measure the real impact of the improvement. Therefore, before the motor change you need to record the existing consumption, running hours and load condition; and after the change, measure under the same conditions. Only in this way can the gain be documented.

Get a Quote

If you are planning a motor efficiency improvement under ISO 50001, contact us with your facility's motor inventory and the information of your priority motors; we will offer support on efficient motor options and a supply plan. For a fast quote and technical support, reach us at +90 (532) 345 49 86 or send your request through our contact page.

Prioritization Checklist

  • Have you built an inventory of all the motors in the facility?
  • Have you recorded each motor's power, speed, efficiency class and age?
  • Have you determined the motors' running hours and load conditions?
  • Have you established the energy baseline?
  • Have you defined the EnPI indicators at the system level?
  • Have you prioritized the most-running and oldest motors?
  • Have you planned the investment in order of payback?
  • Have you set up the continuous improvement cycle?