Customer application 9 October 2019
Room Automation Made Easy

Freiburg im Breisgau stands as one of the most ecological cities in Germany. The new city hall is clear proof of this: In 2017, its first construction phase was inaugurated as one of the first net plus-energy public buildings in the world. The WAGO flexROOM^® room automation system contributes to the city hall's high levels of energy efficiency.

The first net plus-energy public building worldwide is located in Freiburg im Breisgau, Germany. Over the course of a year, the new city hall generated more electricity than it used. The excess energy was supplied to the city electrical network. About 840 employees, previously distributed among different locations in this city section, now work on about 24,000 m² within the building. The building also includes a day care center with an additional surface of 1,500 m². The dedication in November 2017 marked the first construction phase. In the second phase, additional buildings for municipal administrative functions are planned for completion by 2024.

A Concept Combining Comfort and Efficiency

The energy concept of the city hall fulfills the strict criteria of the passive house standards with an annual energy consumption of only about 55 kWh per m² for heating, cooling, ventilation, hot water generation and lighting – this is 40% of the primary energy consumption of a comparable office building. A combination of heat pumps, solar thermal energy and photovoltaics on the roof and facade generate at least this amount. The Drees & Sommer engineering design company developed the building energy concept, which unites high efficiency with user comfort.

This concept also includes the room automation, heating and air conditioning, lighting and even the shading in the office areas. The engineering service provider LAE Engineering was commissioned with planning and installing the room automation. This medium-sized company offers services in the areas of building technology, industry and electricity generation. With around sixty employees, IAE realizes projects for purpose-built structures like office buildings, wholesale stores or factory halls.

Minimum Wiring Expense

“We realized the room automation for the new city hall in Freiburg predominantly with flexROOM^® from WAGO,” states Karlheinz Götz, who manages the Energy and Building Technology section at LAE. The versatile solution for building automation provides lighting, sun protection and temperature control – without any programming. The flexROOM^® System is based on a single system housing in which all necessary components are already built in. In addition to a controller, these components include interfaces to the sensors and actuators, the power supply and a network connection. All of the interfaces have a plug-in design, which minimizes wiring expenses related to installation.

Application software, which functions based on the room axes concept, is already installed on the controller. A single window axis makes up the smallest modular unit, and includes the complete measurement and control system for lighting, shading, heating, and cooling. Several axes can be combined as needed for flexibly designing rooms of any size. Special areas such as corridors, stairwells and sanitary facilities can also be individually designed. The flexROOM^® Distribution Boxes are available in different variants for 8, 16 or 24 axes.

Controlling Lighting Scenes for the Citizens‘ Service Center

The Stühlinger City Hall required a total of around 130 flexROOM^® Distribution Boxes. LAE parameterized them before the installation and then set them into operation on site. As Götz can verify, the fact that each controller is equipped with a Webserver received especially positive notice during commissioning. “The flexROOM^® Distribution Boxes in the rooms could be directly accessed with a laptop via the WLAN connection. This way, we could immediately test each change.” The password-protected access via the Webserver paid off after commissioning as well. “So changes can be made quickly in response to customer wishes without having to leave our own desks,” as Götz is pleased to relate.

Yet there are also applications where flexROOM^® reaches its limits. In the Freiburg City Hall, these are the kitchen, cafeteria and citizen service center. “Because there are no fixed room axes here like there are in the office areas, we used the freely programmable PFC200 Controllers from WAGO,” Götz points out. In addition to heating and cooling, they control different lighting scenes and for the kitchen, the ventilation as well.

To enable calling up the preprogrammed lighting scenes, a 10-inch Web Panel is installed in both the citizens‘ service center and the kitchen manager‘s office. The parameter for the kitchen ventilation system, for example, can be set on these panels. “With flexROOM^®, the rooms in most of the building can be automated – but for special areas, we always need freely programmable controllers,” states Götz. For the project design, LAE turned to the WAGO e!COCKPIT Automation Software. This enables both easy programming in languages that adhere to the IEC 61131-3 standard and easy visualization, which is implemented on a Webserver contained in the controller. This allows the facility manager to change setpoints, and the actual values from various sensors can be read and evaluated.

High Distinction

Among numerous other criteria, efficient room automation is also included in the evaluation of a building for environmental distinctions. The Stühlinger City Hall fulfilled the highest requirements in practically all areas. The builder is especially proud that in 2018, the building was awarded first place in the “Sustainable Building” awards competition organized by the DGNB (German Sustainable Building Council). Götz is convinced, “The energy-efficient room automation made a definite contribution here.”

Text: Michael Dewald

Photo: vor-ort-foto.de

Architect: ingenhoven architects"

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