Building in energy efficiency
May 1st 2008

Malmö is home to MKB Fastighet a company that manages and builds rental apartments and one which takes energy efficiency issues seriously.

It recently investigated the options for optimising energy use in ventilation systems in its buildings. The study showed that it would be worth replacing old fans with new ones that operate with greater efficiency. The company believed that control of the extract fans could be improved by installing a pressure control system that allows outdoor temperature compensation; this can be achieved with variable speed AC drives.

Diana Solutions AB carried out a feasibility study to find an easy way to install the AC drives in the control system. Fast, efficient integration of the AC drives is attributed to the flexibility of the Diana control system.

The control system is located in a boiler room, normally in the basement, and extract fans are on the roof, so signal cabling between control system and drives would form a significant part of the costs. The solution was to use MKB's own broadband network, already installed in the buildings, for communicating between the control system and the central monitoring room.

Selected suppliers of variable speed AC drives that are able to communicate via Ethernet were invited to participate in a test.

Per Platzack, sales manager at Diana Solutions says "Since Vacon AC drives can be equipped with an Ethernet communication board that is integrated into the drive, this was the simplest solution for us. No additional power supply is needed for the communication board and the dimensions of the Vacon IP54 enclosure are very small, giving us a very costefficient installation." Now, 115 Vacon NX drives from 1.1 to 4kW are controlling extract air fans at MKB's various locations.

Smooth starts without torque shocks minimise mechanical stress, which reduces the need for maintenance. They also keep noise from motors and airconditioning ducts to a minimum.

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