36 www. refrigerationandaircon. co. za RACA Journal I October 2026
FANS AND DUCTING feature
There are understandable reasons for this pattern. A motor swap is the lowest visible cost option. Technicians are familiar with installing and maintaining conventional induction motors. Perhaps most importantly, downtime is often critical: a quick motor change is perceived as safer than a more intrusive retrofit which may require longer outages and additional coordination.
The drawback is that this approach does little to address the underlying inefficiencies in the fan system. The belts still introduce losses and maintenance requirements. The fan still runs at constant speed, with airflow controlled by dampers or on – off cycling. Oversizing and mismatches between fan output and actual cooling demand remain. In short, you may achieve compliance and a small reduction in consumption, but you miss the opportunity for transformational savings.
To unlock those larger savings, Schoombie argues for a shift to EC fan systems: electronically commutated, permanent magnet motors integrated with high‐efficiency fan impellers and onboard variable speed drives. EC motors are significantly more efficient than IE3 induction machines, and are generally used in direct‐drive configurations.
The real advantage, however, lies in how EC fans operate under part load. Fan power follows the well‐known cubic relationship with speed. If airflow requirements drop and the fan can slow down, power consumption falls disproportionately. Halving the fan speed roughly halves the airflow, but cuts the power draw to about one eighth of full‐speed consumption.
Traditional systems often respond to lower load by closing dampers or cycling fans on and off. Both approaches waste energy or degrade control. EC fans, by contrast, can continuously adjust speed to match the actual cooling demand. In many applications, this allows average fan speeds to be reduced for large portions of the day, yielding fan energy savings of 30 – 50 % compared to conventional solutions.
In addition, EC fans are increasingly deployed in arrays of smaller units rather than as a single large fan. This provides built‐in redundancy: if one fan fails, the others can increase their speed to maintain airflow and protect product. Integrated electronics handle soft starting, protection functions and monitoring. Many EC fans offer onboard temperature sensing, vibration monitoring and energy metering, which can be linked directly into the building management or supervisory control system.
To make the comparison concrete, consider a 5kW evaporator fan motor running continuously in a freezer. Over a year( 8 760 hours), the baseline energy use is around 43 000kWh. If an older 85 % efficient motor is replaced with a 90 % efficient IE3 motor, the annual energy consumption falls by about 6 %, to roughly 40 000kWh. At an electricity tariff of R2.50 per kWh, that saving equates to approximately R7 500 a year – welcome, but relatively modest for a continuously running load.
LOCAL CASE STUDIES: MEASURED PERFORMANCE These calculations are supported by real‐world data from South African facilities. In one large distribution centre in Johannesburg, condenser fans originally driven by IE2 motors with simple on – off control were retrofitted with EC fans operating under variable speed control. Measured results showed a 40 % reduction in fan energy consumption, with a payback of around two and a half years based purely on energy savings. On the strength of this, the operator began rolling the solution out across other sites.
In another Johannesburg cold storage warehouse, 4kW evaporator fans were replaced with high‐efficiency EC‘ black’ fans. The retrofit delivered approximately 35 % savings in fan energy and improved temperature uniformity in the cold rooms. Because airflow and temperature control were better matched to the actual cooling requirement, compressor runtime could also be reduced. The simple payback period was about three years, but when the project qualified for Section 12L energy efficiency tax incentives, this shortened to roughly 2.2 years.
OVERCOMING BARRIERS TO ADOPTION Despite the strong technical and financial case, adoption of EC and advanced fan systems has been slower than might be expected. Schoombie points to several recurring concerns that need to be addressed.
The first is upfront cost. EC fan assemblies typically cost between one‐and‐a‐half and three times as much as a simple motor replacement. Looked at in isolation, this premium can be off‐putting. However, when the full life‐cycle is considered, it becomes clear that much of a fan system’ s cost over 10 – 15 years is actually energy consumption, not capital expenditure. Short paybacks and tax incentives significantly soften the impact of higher initial prices. Consider the procurement mindset shift, capex versus opex trade-off.
Downtime is another concern. Operators are understandably reluctant to risk extended outages in critical cold rooms. Here, careful planning and modular product design are key. EC solutions can often be implemented in phases, fan by fan or block by block, using retrofit solutions designed to match existing footprints and mounting arrangements that match existing footprints and mounting arrangements. This allows upgrades to be scheduled during planned maintenance windows without compromising product.
There are also questions about technical compatibility and robustness. Historically, EC technology was mainly associated with smaller fans, but today axial EC fans are available in diameters up to around 1 600mm, with a range of options
36 www. refrigerationandaircon. co. za RACA Journal I October 2026