Contemporary ventilation system design is increasingly moving toward simpler and more decentralized solutions. Responding to market demands, designers are moving away from massive, complex systems that cover entire facilities in favor of smaller, independent installations for specific zones or rooms. Below are the primary directions of these changes and their justification.
One of the most prominent trends is the decentralization of ventilation. In large buildings, it is becoming more effective to use several smaller ventilation units instead of one centralized air handling unit (AHU) serving the entire facility. This approach allows for more precise control of conditions in individual zones and simplifies the overall installation structure. Rather than an extensive ductwork network and a complex control system for a single enormous unit, each zone (a floor, section, or even a single retail unit) can have its own dedicated ventilation or air conditioning device.
Independent Regulation: Each zone can be controlled separately, making it easier to match ventilation to local needs and occupant preferences. For example, a clothing store, a restaurant, and a mall concourse can maintain different air parameters based on their specific requirements.
Reduced System-Wide Failure Risk: In the event of maintenance or a malfunction of one unit, the remaining devices continue to operate, ensuring ventilation in other zones. This dispersion of risk means that a single failure does not paralyze the entire building's installation.
Easier Installation and Lower Costs: Smaller units mean shorter duct runs, simpler insulation, and less complicated installation work. Mounting is faster (especially during retrofits of existing buildings) and generates savings during the investment phase. In an era of skilled labor shortages, the demand for fast and intuitive systems is particularly high.
A prime example of this philosophy is found in retail facilities. In modern malls or shopping arcades, each store or service unit increasingly has its own HVAC equipment (e.g., a small AHU, a cassette air conditioner, or individual air heaters) instead of relying on a shared system. The design provides separate systems for common areas (corridors, passages) and independent ones for each tenant. The building infrastructure merely provides utilities to the unit (e.g., connection points for fresh air ducts, refrigerant, or heating water), while the choice and installation of devices—such as multi-split air conditioners or fan coil units—are coordinated between the designer and the tenant.
Extensive, sophisticated ventilation installations—equipped with advanced automation, sensors, and regulators—are now primarily used in facilities that truly require them. These include high-rise office buildings, large shopping centers, public utility buildings, or structures with highly variable loads and rigorous climate requirements. Only in such cases is it justified to invest in complex AHUs serving multiple zones simultaneously, featuring central BMS management and intricate ductwork.
In these demanding scenarios, Variable Air Volume (VAV) systems are employed to automatically adjust ventilation intensity based on current load and occupancy. Using $CO_2$ or temperature sensors, AHUs working with VAV units increase or decrease the volume of fresh air in specific zones as needed, saving energy during low-occupancy periods. While these solutions provide high energy efficiency and comfort, they require more complex control apparatus and careful integration of multiple subsystems. Therefore, outside of critical facilities (such as hospitals, major office hubs, or airports) or buildings with complex structures where space for individual AHUs is unavailable, there is a clear shift away from high-complexity centralized systems toward simpler configurations.
Trends in ventilation design are clearly heading toward simplification and increased system flexibility. Decentralization and localized units are gaining the upper hand in typical projects due to lower costs and easier adaptation to user needs. Meanwhile, complex centralized systems are being reserved for cases where their use is genuinely justified by the scale and requirements of the facility. This evolution in design philosophy aims to improve energy and economic efficiency, as well as the comfort and reliability of building ventilation systems.