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Mar 1, 2013 - Building

1-Wire Technology Efficiently Integrated

The WAGO-I/O-SYSTEM 750 in conjunction with 1-wire technology saved the MIC Clinic in Berlin around 70 percent of the otherwise standard capital costs

Energy efficiency and sustainability ensure significantly lower operating costs, even in building technology. However, the initially higher capital costs spook many owners away from intelligent building technology. The “1-wire” project at the Berlin MICClinic clearly demonstrates that costs are already dropping, even for investments in innovative technology.

The clinic for Minimally Invasive Surgery (MIC) in Berlin Zehlendorf wanted to renovate and modernize 48 rooms distributed over two floors of the of their current, older building. Every room was to be made energy efficient and provided with HVAC that was both individually adjustable and could be simultaneously centrally controlled and monitored. So-called 1-wire technology was employed, which transports the electrical supply as well as transmission and reception data over one wire. If needed, an additional electrical supply for specific sensors can be incorporated using a ground wire. It is possible to connect multiple sensors via one wire.

“With the help of a programmable ETHERNET controller, we were able to centralize the climate controls into one easy to operate control that includes all pumps, chillers, and valves, as well as the automation and monitoring of heating, cooling, and shading. We already saved around 70 percent of the usual capital costs during construction by using both 1-wire technology and WAGO’s automation solution,” confirms Marco Puchalski, CEO of the leading project partner, TPN Service GmbH & Co. KG.

Capital and Operating Costs are Reduced

Single-wire technology involves a very simple bus system using only a single microcontroller pin and simple configuration. Since 1-wire sensors are already being used on a large scale and at low cost per unit (e.g., in mobile data acquisition units), the costs for the clinic project could be significantly reduced by around 70 percent. Using a corresponding interface for the WAGO controller, all necessary measured values can be acquired, while integrating any switch program, independent of manufacturer. Up to 60 sensors can be connected and processed using a single 1-wire module. A standard telephone cable with a protective extra-low voltage of 5 V suffices for connecting to the 1-wire sensors, which again avoids expensive cabling and installation costs.

Error signaling integrated into the sensors indicates faults in the cable connection or in the hardware, among others. A display visualized on a Web server is used for operation instead a classic, building control system. Thus, any PC or mobile device with a browser is sufficient to control the system, even remotely.

An additional aspect in reducing the capital costs was the flexible use of the WAGO controller. Inexpensive standard pumps could be combined with a reasonably priced rotational speed control and regulated using the 750-881 ETHERNET Controller. 50 percent of the acquisition costs were saved up front by not purchasing high efficiency pumps.

There were special challenges presented by the cooling ceiling: According to the manufacturer’s guidelines, the dew point must be constantly monitored in order to carry out a safety shutdown, if necessary. Instead of installing relatively expensive and difficult to maintain dew point sensors, the WAGO controller calculates the dew point using sensor data about air temperature, humidity, and air pressure. To prevent condensation from forming, each individual room can be shaded or the flow temperature can be increased. Depending on the season (heating or cooling operations) the controller autonomously adds an offset value to the system in order to compensate for changes in temperature perception.

Controlling the Systems via Web Browser

Other performance requirements included the regulation of the radiators already existing in the building, the integration of wind and rain monitoring, and overriding the current fire alarm system so that all shading systems automatically rise during an emergency, or the pumps for the cooling ceiling automatically switch off when the pressure drops.

A special challenge in integration was presented by the various shading systems present, such as Venetian blinds, fabric awnings, and interior curtains with the electric motors, as well as the wireless connection of the skylights with the shades. Since each blind has a different, specific sensitivity to wind, and the awnings have to be retracted during rain, individual programing was essential. This had to be as flexible as possible, for example, to automatically close the curtains at dusk. All requirements could be implemented using the WAGO controller. CODESYS (Controller Development System) was used as the development environment for the programmable controller. This program has established itself as the standard in the field of automation technology, is relatively easy to use, and is supported by WAGO’s ready to use program modules and application examples. CODESYS visualization is rendered “Web compatible” by using the integrated Web server for the ETHERNET controller.

Investments Pay Off

“The project at the MIC Clinic is a good example of how investing in intelligent building technology can quickly pay for itself. Both 1-wire technology and WAGO’s automation solution are very powerful and have a decisively good cost-benefit ratio,” states Marco Puchalski about the project results. He also highlights the flexibility and the scope of services. According to his experience, even complex datetime controls can be set using a simple Web operation. “We are very satisfied with the technical equipment for air-conditioning the patients’ rooms. We have a reliable cooling system that is guaranteed to be germ-free, and which is both energy efficient and easy to operate,” confirms Dr. Omid Abri, Medical Director at the MIC Clinic.

Text: Stephan Lampe, WAGO
Photo: MIC Clinic, WAGO

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