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Upgrade to the power of three

EC instead of AC, a new fan type and economical cold aisles — when upgrading its server air-conditioning system, the Danish company William Demant didn't do things halfway.

Generous offices, tasteful furnishings and lots of light: When the Danish hearing-aid manufacturer William Demant moved into its new headquarters, they offered everything the heart desires for a modern office. Only the cooling air-conditioning system in the server room couldn’t quite keep up. Large belt-driven fans ran in the air-conditioning units and used a great deal of energy.

That didn’t fit into the company’s concept, which places great importance on environmental protection and energy efficiency. As a result, those responsible looked around for alternatives. On the subject of air conditioning, Henrik Jensen, Service Manager at William Demant, immediately thought of ebm-papst: “I was already familiar with the products from my previous job and I knew what kind of performance they can deliver.”

Support for a neighbor

It didn’t take long for Henrik Dahl Thomsen, Product Manager at ebm-papst, to get to the first appointment for a visit to William Demant. His office is in the immediate vicinity of the hearing-aid manufacturer. In the server room Thomsen first obtained an overview of the cooling system’s condition. As is usual in rooms of this kind, the air-conditioning units route the warm air out of the server room, cool it down and then blow it into a subfloor. From there the cooled air flows through small openings in the floor and cools the server located in the room.

“However, at William Demant we immediately noticed a special design feature. The AC fans were curved forward and installed quite a bit above the floor and pressed the air downward from there. This had the disadvantage that they actually blew the air directly onto the floor, which then deflected the air flow by 90 degrees. That slowed down the flow of air and made the system even more inefficient.” Together with his partners at William Demant, Thomsen looked for a more efficient possibility and proposed that the fans were not only be replaced, but that their position in the air-conditioning unit would also be changed. As a result, they were no longer to be installed directly in the unit, but instead recessed in the floor. Moreover, Thomsen proposed a backwards curved fan, which routes the air horizontally under the floor directly towards the server.

Simple conversion

“Even though I had never seen this type of installation before, the proposal immediately sounded plausible,” remembers Henrik Jensen. “So we ordered the modifications and a technician installed RadiPac EC fans.” Only minor work was required for this conversion. The installation technician enlarged the hole in the floor of the cooling units, enabling the fans to be recessed in the floor. As the compact fans are supplied as a complete module with a frame, they then only had to be screwed into the opening in the floor.

At the same time, William Demant implemented an additional measure that makes the computer center even more efficient: The company introduced a so-called cold aisle. For this purpose, it installed enclosures around every second corridor in the server room. This enables the cold and hot air to be separated more effectively and the entire system can be operated with less energy due to this clear separation.

This restructuring in the cooling room brought William Demant energy savings of 23 percent, and the conversion to EC fans reduced the energy consumption by another 38 percent. Through the decreased electrical costs, the investment already paid off for the hearing-aid manufacturer after about one year. In addition, the modifications enable the temperature around the server to easily be kept below 27 degrees centigrade (81 degrees Fahrenheit). That’s important, as the servers’ own small fans are not started until this temperature limit is exceeded. If they remain inactive, additional energy is saved.

Thanks to their low noise level, the RadiPac EC fans also make it easier for the technicians to work in the server room, as they can now work with fewer disturbances. Henrik Jensen is extremely satisfied with the upgrade: “The energy savings were even greater than we had hoped. You don’t see that every day.”


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ebm-papst in data centres

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