The main station building in The Hague, The Netherlands, was completed in 1973. It is a 60 m high multi-functional steel-concrete building with glass facade. It has 15 floors hosting offices, shops, and restaurants, with floors 1 and 2 merging with the railway station hall. After 38 years of operation, it was reconstructed in 2011. The main reason for this was high energy consumption: the original energy efficiency of the building was classified as G. The rooms are heated by heat exchangers situated under the windows, where the old control system was replaced by Domat UC230 communicative controllers.
The controllers feature two PWM outputs for heating and cooling, and a separate temperature sensor situated as supply air sensor. The supply air is brought by central floor AHUs. The customer appreciated that Domat Control System offers addressing and configuration of the controllers free of charge, so that the controllers and boxes were equipped with labels containing addresses and target room numbers. This saves time and eliminated installation errors.
Thanks to the open protocol, Modbus RTU over RS485, it was no problem to integrate the room controllers to the building control and management system (supplied by Priva). The communication is used for monitoring, and for control of centralised temperature depressions: the controllers are grouped by flors and floor parts according to usage scenarios and tenants, each group having a separate time schedule.
There is a total of 693 controllers in the building, installed in floors 2 to 13. Typically, there is 60 controllers per floor, only in Floor 2 there are only 30 controllers in the northern part: the other half is part of the station hall. Each floor is linked with a separate bus to its primary DDC process station. Another function is setpoint reset: after the night depression, all daily setpoint corrections are brought to the original values again through a central command. The result of these measures is classification of the building efficiency as D+, and, of course, reduced energy bills for the tenants.