RACA Journal I October 2026 www. refrigerationandaircon. co. za 35
FANS AND DUCTING
For engineers, this means that fan selection increasingly involves more than specifying airflow and static pressure. Motor efficiency, variable-speed operation, controls, noise, maintenance, operating environment, availability of spares and lifecycle cost all need to be considered.
The fan may still have the simple job of moving air. But increasingly, how efficiently, intelligently and reliably it does that job is becoming just as important as how much air it moves.
FROM COMPLIANCE TO PERFORMANCE: RETHINKING FANS IN THE MEPS ERA Francois Schoombie, technical director at ebm-papst South Africa, recently examined the relationship between MEPS, fan performance and overall system efficiency in a presentation in Cape Town.
Minimum Energy Performance Standards( MEPS) for electric motors are reshaping the way South African industry – and especially the HVAC & R sector – approaches energy efficiency. On the surface, the move to higher‐efficiency motors appears to be a straightforward compliance exercise. In reality, it has far‐reaching implications for plant design, operating cost and long‐term resilience.
Schoombie explores why motor efficiency does not equal system efficiency. The real opportunity lies in understanding fans as complete systems and in adopting EC( electronically commutated) technology that enables true optimisation.
South Africa’ s MEPS framework introduces minimum energy performance standards for new industrial motors in the range of 0.75kW to 375kW. This covers the vast majority of motors used in industrial and commercial equipment. Motors are estimated to consume about half of industrial electricity, and in many HVAC and refrigeration facilities, fans and their drives can account for 30 – 50 % of total plant energy use. Motor-driven systems account for + 53 % of global electricity consumption.
The national target of cutting electricity demand by a fraction of a percent may seem modest, but when over half of that demand is motor‐driven, even small percentage improvements translate into large absolute savings. The aim of MEPS is to eliminate the worst performers from the market, align South Africa with international best practice and establish a higher baseline for new installations.
Francois Schoombie, technical director, ebm‐papst South Africa, recently gave a presentation in Cape Town on‘ MEPS compared to fan performance, ascertaining system efficiency’.
© RACA Journal
In refrigeration applications, where equipment often runs 24 hours a day, seven days a week, these incremental improvements are multiplied over thousands of hours, turning seemingly small efficiency gains into substantial financial savings.
WHAT IE3 MOTORS DELIVER – AND WHAT THEY DON’ T Under the new regulations, IE3 becomes the minimum efficiency class for most new motors in scope. Replacing older IE1 or IE2 units with IE3 typically 5 – 8 % energy reduction in practical applications, translating into about 5 – 10 % less electrical energy for the same mechanical output.
Less input power is needed for the same airflow. The motor produces less waste heat, which is particularly important in refrigerated spaces where every additional watt of heat ultimately has to be removed by the refrigeration system. Cooler running motors also tend to last longer, reducing failure rates, maintenance interventions and unplanned downtime.
However, these are component‐level improvements. A fan system consists of much more than just a motor. The efficiency of the belts or couplings, the fan impeller’ s aerodynamics, the control strategy and the way the system is loaded over time all play critical roles. If only the motor is improved while everything else remains unchanged, the overall efficiency gain is inherently limited.
Schoombie uses the concept of an“ efficiency chain” to describe this reality. The motor, transmission, fan impeller and control system each have their own efficiency. The overall system efficiency is effectively the product of these individual stages. From an engineering perspective, the lowest efficiency stage often dominates the final result.
For example, upgrading a motor from 85 – 90 % efficiency is a worthwhile component improvement. But if that motor still drives a belt system with around 15 % losses, turning a fan that is poorly matched to its duty point and controlled at constant speed against dampers, the net effect on overall system performance is relatively modest. The belt losses, aerodynamic mismatches and control inefficiencies remain untouched.
As a result, replacing an IE1 or IE2 motor with an IE3 motor in a traditional belt‐driven, constant‐speed system may only realise a small portion – sometimes around 20 % – of the savings that could be achieved if the entire fan system were optimised. Simply replacing the motor therefore addresses only one element of the system and can leave significant efficiency improvements unrealised.
THE COMFORT OF LIKE‐FOR‐LIKE REPLACEMENT In day‐to‐day practice, the most common response to a failed or ageing motor is a like‐for‐like replacement. The plant removes the old motor, fits a new one with the same power rating and mechanical dimensions, and ensures that it meets the IE3 requirement. From a contractor’ s and operator’ s perspective, this approach is simple, predictable and compliant. feature
RACA Journal I October 2026 www. refrigerationandaircon. co. za 35