Background information:
Air handling units are typically found on commercial buildings and other non-residential buildings. Think of hospitals, offices, cinemas, retail buildings, and so on. Even more modern residential buildings/apartment complexes can have some form of air handling unit. Often, important components of these systems are located on the roof, exposed to all weather conditions. But they are rarely visible from the street. Anyone who looks at the built environment with aerial photographs or satellite images will quickly get a completely different impression. Especially nowadays, air handling units share the limited space on the roof with window cleaning systems, roof gardens, solar panels, skylights, antennas, and so much more.
Construction details:
Air handling units on the roof are often characterized by rectangular, silver-gray air ducts, which in some cases form a veritable spaghetti-like pattern on the roof. This often includes a cabinet or fan system that circulates the air. These systems are often custom-built for each building. Not only the shape and size of the building are important, but also its function. The most modern buildings sometimes already have some of the air ducts internally, reducing cooling and making the building more energy-efficient. Occasionally, dark gray is chosen as the air duct color, for example, if the system's size prevents concealment and it remains visible from public areas.