In large-scale facilities—such as high-bay warehouses, office buildings, or shopping malls—a well-designed mechanical ventilation system plays a critical role. As a Polish manufacturer of Air Handling Units (AHUs), we have identified several common mistakes made during the design and installation phases. These include improper capacity selection, overlooking variable heat loads in different zones, failing to utilize heat recovery potential, restricting service access, or lack of BMS integration.
Mechanical ventilation based on AHUs should be designed optimally for every component—the devices should be neither overloaded nor oversized. Particular attention must be paid to the "heart" of the system: the Air Handling Units. Designing for too low capacity leads to ineffective ventilation, resulting in stuffy, contaminated air that fails to meet temperature requirements. Conversely, an oversized system leads to unnecessary inflation of all ventilation components, resulting in increased investment and operational costs.
When designing mechanical ventilation, it is crucial to remember that a large facility, such as a production hall, may have diverse thermal comfort requirements. The load can change throughout the day and vary by zone. Ignoring this fact results in ventilation, cooling, and heating that are mismatched with real-world demands. This leads to frustrated employees (due to overheating or overcooling), disrupted production processes, and unnecessary costs. The best solution is to use AHUs or air conditioning units with advanced regulation capabilities or systems such as VAV (Variable Air Volume) and CAV (Constant Air Volume).
There are many reasons why the ductwork system supporting AHUs or AC units should be as simple as possible. Often, designers overlook a critical factor that complicates installation at the final stage of investment: the surroundings. During the design phase, it is worth analyzing whether ventilation ducts will have to "compete" for space with other structural elements of the building. Ductless ventilation is often an effective alternative to this problem.
Utilizing heat recovery in an AHU is now a legal requirement. However, heat recovery is more than just a way to comply with regulations and standards. High-efficiency heat recovery is currently a key element in significantly reducing energy consumption in AHUs. Systems such as rotary heat exchangers or counter-flow plate exchangers are recuperators that can reach efficiencies of up to 95%. A well-selected heat recovery exchanger can transform a facility's cost profile and significantly lower utility bills.
Mechanical ventilation relies primarily on air handling and air conditioning units. When designing these systems, we often focus on the final installation cost while forgetting to analyze operational costs—specifically those related to downtime. If an AHU is essential for maintaining operations, it is vital to understand the cost of a single hour of downtime (e.g., on a production line). With this data in mind, the importance of maintaining proper access and service clearance around the AHU becomes clear, ensuring that all maintenance work is completed as quickly as possible.
If a facility is equipped with a BMS, it is worth integrating all capable devices into it. AHUs and AC units are often designed for such cooperation. As a manufacturer, we are convinced that despite the advanced built-in automation we provide with our units, only integration with a BMS allows for their full potential to be realized—especially regarding advanced operational automation.
The errors presented above do not exhaust the topic, but they are the most frequent phenomena we observe. As a manufacturer, we gather these experiences and share them because, in large-scale facilities, small mistakes dictate large sums of money lost to bills, repairs, and complaints—money that can be saved by leveraging the experience of others.