A very large share of the electricity consumed in industry goes to electric motors that turn pumps, fans, compressors, conveyors, and process lines. This leads to a simple but powerful conclusion: every increase in motor efficiency directly means less energy consumption and therefore less CO2 emission. The transition to efficient motors is not only a savings item that lowers the energy bill, but also a strategic decision that reduces a company's carbon footprint and directly affects sustainability reporting and carbon border mechanisms. In this article we cover how emissions per energy are calculated in IE3, IE4, and IE5 transitions, the concept of grid carbon intensity, and the role of efficient motor supply in the green transformation.

The Basic Logic of the Carbon Footprint

The carbon footprint arising from the operation of an electric motor is essentially the emission from generating the electricity it consumes. The essence of the calculation is quite intuitive:

  • Annual energy consumption (kWh): The total kWh depending on the motor's power, load, and operating hours.
  • Grid emission factor (gCO2/kWh): The average amount of CO2 released to the atmosphere in generating each kWh consumed.
  • Annual CO2 emission = Annual kWh × Grid emission factor.

The key concept here is grid carbon intensity (emission factor). This value varies depending on a country's electricity generation mix (the shares of coal, natural gas, hydro, wind, solar, nuclear) and is expressed in gCO2/kWh. As the generation mix shifts toward renewable sources, this factor falls; on fossil-heavy grids it is high. Rather than giving an exact number, it is enough to emphasize this: the same kWh saving provides a greater CO2 reduction on a grid with high carbon intensity.

From Efficiency to Energy Saving, and Then to CO2 Reduction

The difference between efficiency classes comes from reduced losses. When a motor's efficiency rises from 92% to 95%, it draws less electricity from the grid to do the same mechanical work. This difference turns into an annual kWh saving and from there, conceptually, into tonnes of CO2 reduction.

The Conceptual Calculation Chain

  1. The loss difference between two efficiency classes is determined (for example, the efficiency point difference between IE3 and IE4).
  2. This difference is multiplied by the motor's power and annual operating hours to find the annual kWh saving.
  3. The annual kWh saving is multiplied by the grid emission factor to obtain the annual CO2 reduction (tonnes/year).

The most decisive multiplier in this chain is operating hours. While the CO2 effect of an efficiency difference is limited for a motor that runs a few hours a day, the same efficiency difference turns into a considerable CO2 reduction per year for a motor running 24/7. To evaluate the transition decision through operating hours and payback, our article on the IE4 vs IE3 transition decision, runtime, and payback offers a practical framework.

Carbon footprint diagram showing the conversion of energy savings between IE3 IE4 and IE5 efficiency classes into annual CO2 reduction

Emission Difference in the IE3, IE4, and IE5 Transition

As efficiency increases, emission per energy decreases. The general trend is as follows:

  • IE3 Premium: The minimum legal threshold in many applications; a good starting point.
  • IE4 Super Premium: A clear loss reduction compared to IE3; CO2 reduction is distinctly felt under continuous load.
  • IE5 (synchronous reluctance, SynRM): The lowest loss level; it makes the biggest difference especially at variable and partial load.

The IE5 SynRM Advantage at Partial Load

Many pump and fan applications spend most of their time not at full load but at partial load. IE5 SynRM motors, because they operate with a drive and keep their efficiency high at partial load, are the option that most reduces annual energy consumption and therefore CO2 emission in these profiles. To compare the classes in terms of total cost of ownership, you can look at our article on the IE5 IE4 IE3 total cost of ownership comparison.

Scope 2 Emissions and Sustainability Reporting

In corporate carbon accounting, indirect emissions arising from the consumption of purchased electricity are classified as Scope 2 emissions. Electric motors are one of the largest components of Scope 2 in industrial plants. Therefore, moving motors to a more efficient class directly reduces Scope 2 emissions and is positively reflected in the following reporting processes:

  • Annual sustainability / carbon reports.
  • Improvement targets within energy management systems.
  • Product carbon intensity of exporting manufacturers in the context of CBAM (carbon border adjustment mechanism).

As carbon border mechanisms such as CBAM increasingly question the embedded carbon intensity of exported products, motor efficiency on the production line becomes part of competitiveness.

Green transformation with efficient IE4 and IE5 electric motors reducing Scope 2 emissions in an industrial plant

Magnet-Free SynRM Rotor and Recycling Advantage

The carbon footprint is not limited to energy in the use phase; material and end-of-life matter too. One of the most notable features of IE5 synchronous reluctance motors is that their rotors contain no permanent magnets with rare earth elements. This both reduces supply chain risk and facilitates the motor's recycling at end of life; materials such as steel and copper can be recovered more simply. We covered this sustainability dimension in detail in our article on the recycling and sustainability advantage of the IE5 motor.

Payback of Replacing an Old Motor and Green Transformation

Replacing an aged, low-efficiency motor with IE4 or IE5 provides both energy savings and CO2 reduction; these two gains usually overlap. To see how long it takes for the investment to pay for itself, our article on the payback period of replacing an old motor with IE4 offers a practical view. As a manufacturer, HEM Motor offers the IE3, IE4, and IE5 range across 0.55–355 kW from stock with fast delivery and manufacturer assurance, supporting the green transformation and carbon reduction targets of businesses.

Lifetime Carbon: Production, Use, and End of Life

To correctly assess the total carbon footprint of an electric motor, the entire life cycle of the product must be considered. This cycle consists of three main stages:

  • Production (embedded carbon): The energy spent in processing steel, copper, and cast materials. Compared with the energy the motor consumes over its life, this share is usually small.
  • Use phase: The overwhelming majority of the carbon footprint occurs here. For a continuously running motor, the lifetime energy cost is many times the purchase price.
  • End of life: Recovering materials through recycling reduces the raw material and energy needed for new production.

When these three stages are evaluated together, it becomes clear that the greatest carbon gain comes from efficiency in the use phase. Therefore, raising the efficiency class on a high-operating-hour motor is the most effective way to lower the lifetime carbon footprint. This logic also lowers the total cost of ownership of the efficient motor.

The Additional CO2 Contribution of Speed Control with a Drive

In addition to the efficiency class, how the motor is driven also directly affects the carbon footprint. In variable torque applications such as pumps and fans, slowing the motor with a variable frequency drive instead of throttling the flow with a valve or damper significantly reduces energy consumption. According to the fan and pump law, as speed decreases, power consumption decreases in proportion to the cube of speed; that is, even a small speed reduction provides a large energy and therefore CO2 saving. Since IE5 SynRM motors already operate with a drive, this advantage is obtained naturally. In this case two gains combine:

  • The fixed loss reduction from the high efficiency class.
  • The advantage of drawing energy according to actual demand, from speed control.

As a result, applying an efficient motor together with drive control is one of the fastest-paying investments in carbon reduction in industry.

Efficient Motor Supply and Carbon Targets

For a business that wants to reduce its carbon footprint, the most concrete step is to move the high-operating-hour motors on its line to an efficient class. You can request a quote for the right power, mounting (B3, B5, B14, B35), protection class (IP55, IP65/IP66 on request), and, if needed, a drive package for IE5; and get information about current electric motor prices and lead times. This way you lower both your energy cost and your Scope 2 emissions with the same investment.

Frequently Asked Questions

How does increasing motor efficiency reduce CO2 emission?

A more efficient motor does the same mechanical work while drawing less electricity. Since there is a certain amount of CO2 emission behind every kWh consumed, as annual kWh consumption falls, annual CO2 emission decreases directly. The magnitude of the effect depends on operating hours and grid carbon intensity.

Why is the grid emission factor important?

The same amount of energy saving provides a greater CO2 reduction on a grid with high carbon intensity (fossil-heavy). As the generation mix shifts toward renewables, the factor falls. Therefore, in the CO2 calculation, the grid's gCO2/kWh value is as decisive as the kWh saving.

Why is an IE5 SynRM motor advantageous for carbon targets?

IE5 SynRM motors have the lowest loss level and keep their efficiency especially at partial load. Because they operate with a drive, they reduce energy consumption the most in variable loads such as pumps/fans. In addition, their magnet-free rotors facilitate end-of-life recycling, contributing positively to the total carbon footprint.