A successful upgrade at the iconic Wakefield House Building in Adelaide has achieved power savings at the site of 194,000kWh per annum.
The outstanding result was part of a two step retrofit program undertaken at Wakefield House to overcome a poor fan installation and to meet National Construction Code (NCC) standards.
ebm-papst ANZ sales manager Daniel Capovilla, said the first stage involved retrofitting a direct drive EC plug fan in place of the belt driven dual inlet backward curved blower on a single floor.
This was before the project was rolled out to the entire building generating power savings of 194,000kWh per annun. He said changes to the air handling units were also required to improve airflow over the heating/cooling coils.
“We wanted to reduce air patching and increase cooling capacity and airflow,” Capovilla said. “Why backward curve and not forward? Physics makes forward less efficient than backward curve. We replaced the belt fan with a centrifugal fan before replacing the AC fan with an EC. Centrifugal fans require set space, a minimum separation distance is required.”
Capovilla said 100 per cent of air is rarely required so they used speed control to run the fan at 50 per cent.
“We took eight fan condensers and turned the fans down by half expecting 50 per cent power savings, but we actually achieved a saving of 87 per cent and reduced noise levels by 15dbd,” he said.
System Solutions Engineering director Kevin O’Reilly, said the biggest problem was lack of performance with the fan blowing straight into the coil.
“This reduced airflow significantly plus we had a lack of outdoor air and it’s a 19-storey building,” he said. “We separated the coil and fan, created a positive chamber and put a damper on top of the coil. This increased the outdoor air rate to 600 litres per second.”
O’Reilly said the only hiccup during the project was the Hastie Group collapse, which forced them to change contractors.
“The EC motors were purpose built to load; we made improvements to the chillers and a BMS upgrade was done,” he said.