© Steven Pam/Smartshots

Better skyscraper air conditioning

The fans in the air conditioning system at the Riverside Centre, one of Brisbane’s landmarks, were wearing out. A retrofit was needed to improve efficiency and convenience, but there was hardly any room and not much time.

With its wavy contours, glass-fronted lobby and unique view of the Brisbane River, the 146-meter-high Riverside Centre is a landmark in the capital city of the Australian state of Queensland. The skyscraper’s 40 stories are home to numerous offices and to cafés and restaurants on the riverfront that are popular destinations for locals and visitors alike. A listed building in the heart of the financial district, it was designed by the renowned architect Harry Seidler and completed in 1986.

After more than 30 years, the building’s façade was still gleaming like new but the original centrifugal fans in its air conditioning system were wearing out. “The bearings were damaged and starting to stick, the belts and pulleys were worn, and there were signs of pitting corrosion on the impellers,” says Andrew Prentice, a mechanical engineer and consultant for the project team. A retrofit was planned to extend the life of the air conditioning system and improve its energy efficiency and customer convenience.

Smaller but more efficient

The original plans called for replacing the backward-curved dual centrifugal fans in the six cooling units with larger EC plug fans with diameters of 800 and 900 millimeters. But ebm-papst Australia proposed installing smaller fans with a diameter of only 500 millimeters instead, which would simplify transport and installation. “It would have been pretty unrealistic to put a crane in a building in the middle of Brisbane’s financial district,” says Andrew Prentice. Part of the upgrade involved installing larger and more powerful heat exchangers, which reduced the amount of space available for installing the fans. “So we had to minimize the size of the fans while increasing their efficiency,” says Brett Saunders, CEO of the installation firm Hiflow.

Hiflow replaced one large backward-curved dual centrifugal fan with up to ten EC plug fans from ebm-papst arranged in a two-by-five fan grid. The small fans were transported to the installation site by pallet jack and freight elevator. Only two technicians were needed to install the fans. That made a quick retrofit possible, an important factor for the customer. The technicians were only able to start replacing the cooling units on Friday evening after work; all cooling units were to be replaced and running by Monday morning when the office staff returned to their desks. “We were actually done with the retrofit on Saturday,” says Saunders proudly.

Outstanding environmental performance

The new, smaller fans consume 38 percent less energy. With an air conditioning system that accounts for 60 percent of the building’s energy consumption, that makes a huge difference for every one of its office tenants. Not only does the Riverside Centre gleam on the outside, it’s now also a star in Australia’s NABERS environmental rating system, receiving five-and-a-half out of six possible stars for its environmental performance.

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