Picture the scene: an engineering team at a processing facility decides it is time to modernize. They identify a motor running below current efficiency standards, procure a shiny new IE4-rated replacement, install it correctly, and duly record a compliance win. Job done. Or is it?
According to industry experts consulted as part of a government-backed review of the UK’s Ecodesign Regulations for electric motors and variable speed drives (VSDs), that scenario plays out on sites across the country—and it routinely leaves the biggest energy savings untouched. The motor gets upgraded, but the system it sits in does not.
Thomas Marks, Director General at the Association of Electrical and Mechanical Trades (AEMT) , argues that focusing narrowly on motor efficiency ratings is, at best, an incomplete strategy. At worst, it can be an expensive distraction.
The Blinkered Upgrade
The efficiency classification system for motors—running from IE1 through to IE5—has undeniably driven improvements in products entering the market. Regulations have successfully phased out the least efficient motors, and the difference between, say, an IE2 and IE3 motor represents a meaningful reduction in running costs for many applications.
But specialists are increasingly vocal that chasing the next efficiency class on the motor nameplate can lead operators to miss the larger picture. As Johnathan McNamee from Hayley 24/7 explained: “The whole concept of going from IE2 to IE3, or three to four, can be a little bit blinkered. Sometimes people don’t look at the whole system enough.”
The point is not that motor efficiency standards are irrelevant—they are not. It is that the motor is just one component in a wider mechanical system, and often not the one with the most room for improvement. The gains from a motor upgrade can be dwarfed by issues such as:
- An inefficient gearbox
- A poorly aligned drivetrain
- A chain drive running at the wrong tension
- A pump that has been manually throttled to restrict flow
Fraser Lynch of Westin Drives made that point with a vivid example: “We went out, fitted an inverter and an energy-efficient motor—then noticed the pump was manually valved off to restrict flow. Just opening that valve saved far more than anything we’d just done.”
That quote from a job at a quarry captures the problem neatly. A pump had been running against a partially closed manual valve, wasting energy continuously. Opening the valve after installing a VSD cost nothing and delivered savings that eclipsed the entire investment in new equipment.
The Budget Disconnect
There is a structural reason why sub-optimal decisions keep being made, and it has little to do with technical ignorance. It comes down to how budgets are allocated. In many organizations, engineering departments are responsible for procurement and maintenance, but energy costs sit in a completely separate budget. The engineer tasked with replacing a failed motor is measured on capital expenditure, not on kilowatt-hours saved.
Andy Patten of ADC Electricals observed: “Engineering departments don’t really have that much interest in what the efficiency ratings are or the energy savings, because ultimately that doesn’t come out of their budget. Their focus is simply on what their budget is and how much the unit costs.”
The consequence is predictable: the most energy-efficient option is rarely selected at the point of purchase. The fix requires organizational change as much as technical change—aligning procurement decisions with whole-life energy costs through internal charge-back mechanisms, life-cycle cost analysis tools, or ensuring energy managers have a seat at the procurement table.
Where the Real Gains Are
Experts agree that for most motors in service, the incremental gains from moving up another efficiency class are becoming marginal. The easy wins from motor design have largely been captured. As Andy Patten put it, the industry has “reached the peak where it’s a lot of money to spend to save a fraction of a percent.”
The better opportunities now lie elsewhere. Three areas worth examining on any site:
- Variable Speed Drives (VSDs): Adding a VSD to an application that runs at fixed speed can deliver substantial savings, often with a rapid return on investment. Pumps and fans running at full speed but with throttled output are prime candidates.
- Right-Sizing: One of the most common sources of energy waste is oversized motors. A motor running well below its rated load operates inefficiently. Replacing it with a correctly sized unit can realize immediate savings.
- The Wider Drivetrain: Gearboxes, couplings, belts, and bearings all introduce losses. Unlike motors, these components have seen far less regulatory attention. A thorough system audit may reveal that the gearbox or pump is a greater source of inefficiency than the motor driving it.
Measure Properly Before You Act
Any assessment of system efficiency is only as good as the data behind it. Extended monitoring that captures performance data across representative operating cycles—ideally over several weeks—provides a much more accurate picture of where energy is actually consumed. Condition monitoring technology has advanced significantly and is increasingly accessible for industrial operators of all sizes.
A Practical Framework for Equipment Owners
The takeaway is not to ignore motor efficiency standards—compliance remains a legal requirement. Instead, treat motor replacement as an opportunity for a broader conversation. When a motor comes up for replacement, ask these questions:
- Is this motor the right size for the actual load it drives?
- Is the driven equipment operating at its designed efficiency?
- Could a VSD be justified on energy-saving grounds alone?
- When were the gearbox, coupling, and transmission components last assessed?
- Who in the organization is looking at the lifetime energy cost of this asset?
- Has enough operating data been captured to understand real-world performance?
These questions cost nothing to ask. The answers could be worth considerably more than the most efficient motor on the market.
