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When a university hospital in Switzerland faced a sudden ventilation failure, it was not just a crisis—it became a turning point. Instead of simply replacing the broken belt-driven fan, the hospital upgraded to an Electronically Commutated (EC) fan array system. The result was improved efficiency, better air quality, lower maintenance, and significant long-term savings.
This retrofit is not an isolated example. HVAC professionals around the world are increasingly turning to EC fan arrays to modernize outdated systems and meet today’s demands for energy efficiency, indoor air quality, and regulatory compliance. With the introduction of EU Regulation 2024/1834 and evolving U.S. codes, EC fan arrays are more relevant than ever.
Here are eight key reasons why this technology is transforming the HVAC retrofit market.
1. Higher energy efficiency with a fast return on investment
Unlike conventional belt-driven motors, which lose energy through slippage, friction, and mechanical transmission losses, EC motors use permanent magnets and integrated electronics to optimize power usage. This design minimizes energy loss at every stage of operation. The result is a motor that routinely operates at efficiencies between 80% and 96%, depending on load and application.
In the Swiss hospital retrofit, the facility replaced a single large AC belt-driven fan with four EC fans in an array configuration. As a result, annual energy consumption dropped from 86,566 kilowatt-hours to 20,007 kilowatt-hours. This change yielded annual utility savings of over $10,000, reducing the hospital’s total ventilation energy costs by approximately 77 percent.
Figure 1: Original Swiss Hospital Belt-Driven Fan (Courtesy Ziehl-Abegg)
Figure 2: New Swiss Hospital EC Fan Array (Courtesy Ziehl-Abegg)
Because energy savings accrue month after month, most organizations recover their initial investment in under five years. In this case, the hospital’s full investment of $32,490 was recouped in less than three years.
Figure 3: Swiss Hospital Fan Cost Comparison (Courtesy Ziehl-Abegg)
2. Improved airflow distribution for better comfort and system balance
Traditional fans often deliver uneven airflow, particularly in large open spaces or older duct networks. This can lead to uncomfortable hot and cold zones, noise complaints, and imbalanced system pressures. Over time, these issues can strain other mechanical components, reduce occupant comfort, and increase energy consumption.
By contrast, EC fan arrays distribute airflow more evenly throughout the space. Multiple smaller fans working together generate homogeneous airflow conditions that reduces air turbulence and noise. Each fan can be independently controlled to match specific performance targets, improving system responsiveness.
In the Swiss hospital example, replacing a single large fan with an array of four EC fans eliminated airflow inconsistencies, resulting in improved thermal comfort for patients and staff.
Figure 4: Air Velocity Comparison of 1 Large Fan to 8 Smaller Fans (Courtesy Ziehl-Abegg)
3. Built-in redundancy prevents system downtime and enhances reliability
A common risk in traditional single-fan systems is total failure. If the only fan serving a critical area breaks down, the result is a complete loss of airflow until the system is repaired or replaced. In healthcare, laboratory, and data center environments, this type of downtime can be unacceptable.
EC fan arrays solve this challenge through redundancy. By designing the array using the N+1 principle, engineers include one more fan than necessary to meet the required duty point, airflow and pressure. If one fan fails, the remaining units can be programmed to automatically increase speed to maintain airflow. This ensures continuous operation with no loss of ventilation.
4. Compact and lightweight design simplifies installation and logistics
Traditional belt-driven fans are often large, heavy, and difficult to maneuver. Their installation typically requires cranes, oversized doorways, reinforced floors, or even wall demolition. These constraints drive up labor costs and increase installation time.
In contrast, EC fan arrays are modular, compact, and lightweight. Most models can fit through standard doorways and elevators. Two technicians can usually carry and install an EC fan without special equipment. This simplifies logistics and reduces project costs.
In the Swiss hospital retrofit, the entire installation was completed by two people in just four working days. This level of simplicity is a major benefit in retrofit projects, particularly in older buildings or space-constrained areas.
5. Reduced maintenance and fewer mechanical issues
Belt-driven fans require frequent inspections, realignment, belt tensioning, and periodic replacement of belts and bearings. These components experience wear and tear, leading to increased maintenance costs and unexpected downtime.
Because EC fans are direct-drive and do not rely on belts or pulleys, they eliminate many of the common failure points found in legacy systems. The onboard electronics also allow for precise speed control without the need for external Variable Frequency Drives (VFDs), further reducing complexity.
With fewer moving parts and minimal routine maintenance, EC fan arrays allow facility teams to focus on proactive system optimization rather than reactive repair. This long-term reduction in maintenance costs contributes to a stronger return on investment.
6. Compliance with global efficiency regulations
Energy regulations are evolving rapidly, and EC fan arrays help facility owners stay ahead. In the United States, the Department of Energy (DOE) introduced standardized test procedures for commercial and industrial fans in 2023. While a proposed federal efficiency standard was withdrawn in January 2025, states like California have moved forward with their own legislation.
California’s Title 20 mandates that applicable fans and blowers meet a Fan Energy Index (FEI) of 1.0 or greater and be listed in the California Energy Commission’s efficiency database. This standard applies to all equipment classes and includes requirements for proper labeling and documentation.
Meanwhile, the European Union has released EU Regulation 2024/1834, which updates and replaces previous Eco-design fan standards. Effective July 2026, this regulation applies to fan systems between 125 watts and 500 kilowatts and establishes minimum efficiency thresholds. The regulation also includes detailed documentation and labeling rules for manufacturers and importers.
7. Cleaner indoor air and healthier environments
Indoor air quality is a growing concern in commercial and institutional buildings. Belt-driven fans can release particulates as belts wear out, particularly if maintenance is delayed. These particulates circulate through the air distribution system and may compromise health or require additional filtration, especially in hospitals, schools, and laboratories.
EC fans offer a cleaner alternative. Because they use direct-drive motors, there are no belts to shed particles. The result is cleaner ductwork, less filter clogging, and improved air quality. This is particularly beneficial for critical applications where occupant health and environmental control are top priorities.
In the Swiss hospital, the retrofit reduced particulate generation and eliminated the need for additional filtration upgrades, saving money while improving health outcomes.
8. Scalable, adaptive systems for diverse building types
One of the greatest strengths of EC fan arrays is their flexibility. The modular design allows engineers to customize the array size to fit each application, whether in a hospital, data center, office building, or manufacturing plant. Arrays can be expanded, reconfigured, or upgraded as building needs change.
The fans can be programmed to adjust output based on occupancy, time of day, or seasonal variation. This smart control enables more precise ventilation strategies and reduces unnecessary energy use.
Because fans are standardized and interchangeable, facility teams can stock spare units and perform fast replacements when needed. This reduces system downtime and extends service life.
Final takeaway: EC fan arrays offer unmatched value in modern HVAC retrofits
EC fan arrays combine performance, efficiency, and reliability in a compact, serviceable package. Whether driven by rising energy prices, regulatory pressure, or sustainability commitments, the case for upgrading to EC technology has never been stronger.
With lower operating costs, simplified installation, enhanced comfort, and future-ready compliance, EC fan arrays offer a smart and scalable path forward. For building owners, engineers, and facility managers seeking the best return on investment, the answer is clear.
Retrofitting with EC fan arrays is not just a solution for today’s HVAC challenges. It is an investment in tomorrow’s efficiency, resilience, and sustainability.
By Nicholas Popp
Ziehl-Abegg Inc. R&D Engineer – Standards and Regulations
Nicholas Popp is a Standards & Regulations R&D Engineer at Ziehl‑Abegg Inc., bringing over five years of expertise in developing cutting‑edge ventilation and drive technologies. A graduate of the University of Central Oklahoma, he specializes in navigating regulatory landscapes and ensuring product compliance. Based in Greensboro, NC, Nicholas is dedicated to advancing sustainable engineering solutions that meet global standards and market needs.