Silent heroes

The plight began six years ago with the instal­la­tion of a new venti­lation system. The noise that this system gener­ated was conveyed through the venti­lation ducts into all rooms of the psychi­atry ward at the univer­sity hospital in the Danish city of Odense. It was noisy in the building, the instal­la­tion company disap­peared and simply refused to do anything about it.

Cheap fans cause headaches and tired­ness

Jørgen Søfeldt, Func­tion Manager at the Univer­sity Clinic in Odense, is pleased with the silent fans.

Jørgen Søfeldt is a Func­tion Manager at the clinic. He recalls: “The situ­a­tion was so bad, we had to signif­i­cantly curb the motor for the venti­lation to make the noise level halfway toler­able.” Torben Lintrup Kirk­holt, Managing Director of ebm-papst Denmark, describes the situ­a­tion: “There was still an audible rumbling throughout the building, like a clothes dryer full of tennis balls.” That was bad for the patients, who are often partic­u­larly sensi­tive to noise. But there was worse to come.

“The venti­lation system was only running at 60 percent capacity. That meant that the air exchange rate and the air flow needed for a healthy inte­rior climate were nowhere near achieved”, reports Kirk­holt. “There­fore it was too hot in the building, the CO2 concen­tra­tion in the air was much too high and it was so humid that mould formed in the corners, all the ingre­di­ents for sick building syndrome.”

“The system was making a noise like a clothes dryer full of tennis balls.”

Torben Lintrup Kirk­holt, Managing Director of ebm-papst Denmark

The humid room climate and the mould threat­ened the health of both doctors and patients. Ambient air with a high CO2 content also leads to tired­ness, loss of concen­tra­tion, headaches and dizzi­ness. Opening the windows for some fresh air was not an option for the psychi­atric ward, as they could not be opened for safety reasons. Stuffy, humid and loud – not the ideal envi­ron­ment for patients who should be able to rest in peace and quiet.

Before: Conven­tional AC. After: Energy-saving, virtu­ally silent RadiPac EC fans.

The solu­tion came as a bit of a coin­ci­dence. Søfeldt reports: “In other parts of the univer­sity hospital building like the kitchen and laundry, we had had energy-saving fans installed by ebm-papst. When I described our noise prob­lems in the psychi­atric ward in passing to the ebm-papst staff, they said they might be able to help.” ebm-papst replaced one of the old fans as a trial.

Kirk­holt explains: “They were only about six years old, but used 1980’s tech­nology: a poor AC elec­tric motor with a cheap frequency inverter and an impeller made from low-grade sheet metal. These three things together caused the noise prob­lems. You could tell right away that the company that had installed these were only inter­ested in fitting the cheapest devices possible.” Every­thing was fine with the RadiPac EC centrifugal fan which was installed. Søfeldt was surprised: “We had no idea that it was just the old fans that were causing the noise!”

Better climate, lower costs

The deci­sion was an easy one: all twenty of the old fans had to be removed and replaced by the EC centrifugal fans. ebm-papst completed the job in a week. The system now runs at full capacity and the climate in the room is perfect. And impor­tantly, no noise. The icing on the cake is the amount of energy saved. Thanks to the EC fans, the psychi­atric clinic now saves around 5,650 euros on its annual elec­tricity bill. The fans will have paid for them­selves in just seven years. 

Read on with an inter­view with Dr Marc Schneider, ebm-papst’s Group Leader for Acoustics about noise emis­sions.