The new building for the Minden Campus of Bielefeld Technical College is a pioneering project for two reasons: It integrates cutting-edge energy and automation technology, and is also a prime example of cross-discipline, integrated construction. Due to close collaboration, the designers and building trades reached a precise target in quality and costs.
Constructing a building is not always a smooth operation. Although construction sites generally bustle with technical planners and trade workers, coordination and communication between these groups is often in need of improvement.
One of the potential causes for these difficulties lies in the rules for tendering bids, as it is customary to incrementally assign the individual construction tasks over the course of a project. Thus, some companies only arrive on site after others have already left – which makes collaboration between skilled trades more difficult. The Bielefeld University of Applied Sciences, as the owner- occupier, and NRW, a property management and construction company (BLB NRW) have charted a new path in the construction of the Applied Sciences building on the Minden campus. “In contrast to previous arrangements, we met with all the planners at the same time to create a common base for optimum solutions,” explains Oliver Wetter, Dean of the Minden campus. The cooperation paid off: After 22 months of construction, BLB NRW completed the new building on schedule and within the 14 million euro budget – something that should not be taken for granted in construction projects of this magnitude.
Maintaining the budget in terms of quality and costs was not easy; the University of Applied Sciences wanted an intelligent building with sophisticated energy and automation technology. The Minden campus has traditionally focused on engineering, including a Master’s program in Integral Construction This brings architects, civil engineers, and project managers together to provide students with a foundation in construction planning across the building trades. Therefore, BLB NRW designed a four-story “meeting center”, with offices, work spaces, a library, and a cafeteria, which also functions as a research and teaching facility due to the modern energy systems and intelligent building technology. Lighting, energy generation and distribution, air conditioning, and sun protection are automatically controlled and monitored using building automation that covers all the skilled trades and extends from individual systems up to complete room automation. The idea is for the students to evaluate the energy data directly via a communication interface in the network, so that they learn how these intelligent building automation systems function, and how to program them. “This allows them to further increase the use of the building through their research,” explains Wetter.
There are, as yet, few buildings of this type in Germany. The Minden campus construction is currently one of two university buildings in the country that already fulfills the high demands of energy efficiency class A. According to the Energy Saving Ordinance of 2014, this mean that no more than 50 kilowatt hours per year, in the form of electricity and heat, can be consumed per square meter. In comparison: the consumption in public buildings is usually around twice as much – they only achieve efficiency class C. The reason: investments in room automation are necessary in order to achieve the consumption values required for class A. However, public-sector budgets are not sufficient for the standards from 2012, the year the classification was established. For the campus project, the University of Applied Sciences took responsibility for the costs of the intelligent building automation, for a total of 113,000 euros. “We were able to convince the University President that the higher efficiency class would benefit research and teaching,” states Wetter.
The decisive argument: building automation may have higher initial costs; however, the investment more than pays for itself through operating cost savings over the lifetime of the building. To increase energy savings, the building includes a well-insulated structural shell, recovers waste heat from the servers in the computer lab, and supplements with energy from a geothermal system. Its probes draw warmth from the earth which is transferred to a heat pump, which in turn increases the low temperature of the geothermic warmth in order to heat the building. Due to the reversible operation of the heat pump, the library, cafeteria, foyer, meeting areas, and workshop are cooled using the underfloor heating system and radiant ceiling panels – and energy extracted here is used to regenerate the ground probe field. A second heat pump is linked into the combined storage for the server cooling/geothermic system, and is also used for the combined heating system. A gas condensing boiler provides hot water and is reserved for peak loads. Cooling peaks are accommodated by two chillers. In addition, free cooling is integrated into the combined cooling system. The entire system technology is designed to minimize primary energy consumption.v
Open Communication Through BACNET
BACnet/IP controllers from the WAGO-I/O-SYSTEM 750 play a central role in plant and room automation. A total of 21 of these systems were installed in the new building. Seven controllers comprise the classic information nodes for heating, air-conditioning and refrigeration, and 14 units take on the automation functions for the individual floors. All control units are networked together via an ETHERNET network. BACnet provides a standardized, open-source data communication protocol, which enables data communication between devices from different manufacturers according to the detailed specifications of the construction planning (assuming, of course, that these devices likewise support the BACnet standard). As controllers for the instrumentation, control, and automation technology, the WAGO technology ensures that the central systems – like the heat pumps or the geothermal system – function problem-free, and that these systems, in conjunction with ventilation, always provide the desired temperature.
Room automation includes lighting, sun shades, and room temperature regulation. Carbon dioxide air quality controllers are also in use in the practical labs and seminar rooms. Feedback signals from the window contacts are likewise detected and processed in the automation programming. In order to detect all of the signals at the room level, Hermos AG, from Mistelgau, uses the modular structure of the WAGO-I/O-SYSTEM and special connectors for the DALI, KNX, and SMI sub-bus systems. The different room functions are activated via KNX room operating panels. According to the specifications in the system integration sheets, all facility and room automation information, as well as additional monitoring functions for all building systems are linked to a BACnet management service level in order to monitor and adjust the building automation at any time. With their help, the building’s energy data can be recorded and analyzed, the setpoints or occupancy times can be changed, and all values and conditions, such as temperatures, operating messages and faults from all systems, can be visualized as both a forecast and review using time-lapse.
Trained WAGO experts closely examined the building technology in Minden as part of the eu.bac certification process. The audits create transparency and provide operators with comprehensive information about the automation technology used in their buildings. The systematic evaluation helps obtain targeted savings in energy and operating costs over the entire life cycle. To this end, the eu.bac system certification for buildings sets new standards. In previous certification programs, building technology was barely considered: the eu.bac approach rectified this lack in 2013. The method is based on scientifically tested data and the relevant DIN EN 15232 European standard. The audits may only be conducted by recognized experts, trained and certified according to the specifications of the eu.bac (european building automation controls association).
The Minden project has thus become a beacon in many respects. It is not just a model for interdisciplinary, integral building, but also demonstrates how the energy efficiency of the new Minden campus building can be sustainably improved thanks to state-of-the-art building automation and evaluation methods. The “eu.bac system” certificate documents that the technology and automation in the campus building are designed to be sustainable and energy-efficient for optimum comfort. Trained WAGO experts closely examined the building technology in Minden as part of the eu.bac certification process.
Text: Joerg Gruner
Photo: Andreas Secci, Robert B Fishman