© photos: ebm-papst

Roof-top data

The trend toward huge logistics centers presents new challenges for air conditioning systems. And another important criterion for the online mail order company Zalando is data acquisition. In just under a year, the online mail order fashion company Zalando erected a logistics center in Lahr with 130,000 square meters of floor space.


One large logistics center after another has sprung up near Lahr in the Black Forest. The task of cooling and heating the building complex fell to the air conditioning company MultiCross. The aim was to make sure the temperature remains a constant 22 degrees Celsius at all times in every last corner of the logistics center – both in summer and in winter. “Zalando demands very high standards for the working environment and base their planning on extremely tight tolerances. When they say a constant 22 degrees absolutely everywhere, that is exactly what they mean,” explains Frank Reimann, Managing Director of MultiCross.

Frank Reimann, Managing Director of MultiCross, enjoys the pleasant atmosphere in the Zalando logistics center canteen.

An enormous challenge in the so-called order picking warehouse, for example, where the employees retrieve the items from the shelves: This warehouse consists of 175 rows on five levels, tightly packed with boxes of clothes. The air duct design in this part of the building is particularly complex. And it involves having to circulate a total of around a million cubic meters of air per hour.

So a large-scale solution was called for. MultiCross installed 25 heat recovery systems on the building roof, each the size of a double garage. The installations are driven by 84 gas engines. Direct evaporator registers with four circuits per unit generate just the amount of cold or heat required at any given instance – no more and no less.

On the roof of the hall there are 25 heat recovery units, 84 gas engines and a direct evaporator register.

There is a particularly great need for fresh air in the Zalando facilities on account of the odors given off by textiles, leather and cardboard boxes. Which is why MultiCross decided in favor of an additional solution for heat recovery. In view of the large size of the building roof, the company planned to install the units in lengthwise arrangement with a lot of distance between the exhaust and inlet air – offering both enhanced efficiency and simplified maintenance.

On top of the administration block, the latest generation of quiet-running, energy-efficient RadiPac EC centrifugal fans in FanGrid arrangement provides constant air exchange.

Saving energy in the administration block

The heat recovery system above the administration block with offices, kitchen, canteen and changing rooms, is fitted with particularly efficient and quiet-running RadiPac EC fans from ebm-papst. The inlet ring is perfectly designed for the impeller with its aerodynamically optimized blade channel. This lessens turbulence right at the air inlet, thus reducing flow losses and eliminating one of the causes of noise nuisance. In addition, the transition from the inlet ring to the impeller cover plate has been designed to produce a clearly defined gap flow. As a result the turbulence in the air flow, which would narrow the effective flow cross-section, is reduced at this point as well. This is another factor enhancing the efficiency of the system as a whole.

The horizontal system configuration also facilitates maintenance work.

The gentle rounding at the blade inlet also helps to reduce noise. It ensures low-loss blade inflow. The profiled contour guides the air flow through the blade channel, before it leaves the impeller with hardly any turbulence thanks to the thin trailing edge. The specially shaped impeller base plate largely routes the air outflow in axial direction. This reduces both the deflection losses in the air conditioner and the pressure drop in the installed unit. The FanGrid arrangement additionally enhances efficiency, as well as increasing operational reliability. An optimally positioned pressure tap is also provided as standard for air flow measurement. This facilitates commissioning for MultiCross.

Satisfying the hunger for data

It was however another feature that finally made Zalando decide on RadiPac EC fans. Reimann: “We realized that Zalando was established as a digital start-up company in 2008. The company is digitized through and through. They were pleasantly surprised to find out that so much data can be gathered from the fan: Speed, temperature, operating time, power – the Zalando building services department performs a lot of data analysis.” The MultiCross EcoSmart software processes the most important data in clear-cut form and makes it available to Zalando for control purposes.

The MultiCross EcoSmart software processes the most important data in clear-cut form and makes it available for control purposes.

In the event of anomalies, the MultiTrend Viewer digital assistant developed in conjunction with ebm-papst sends a warning email to the applicable technician, or MultiCross can take action in the form of remote maintenance.
“With the trend toward smart building services and Industry 4.0, more and more customers expect this sort of system as standard. So it is a great help that the EC fans can simply be actuated via MODBUS RTU for example, and it is no problem to incorporate them into an information system.”

The RadiPac EC centrifugal fans have appropriate interfaces for feeding all sorts of data into the control system of the logistics center – an aspect of great importance to Zalando.

Greater efficiency thanks to Big Data

Sensors in the logistics center buildings measure the CO 2 concentration, room temperature and other values. The data are fed directly into the company network for further use. The heat recovery systems retrieve the values from the network through device addresses. And the data form part of the overall picture as well, because there is a simple reason for Zalando’s hunger for data: The company is in the process of creating central software for all logistics centers, containing the data from all building services – and not just from the air conditioning system. By comparing the values on the basis of various factors of influence, Zalando is hoping for greater efficiency in its current operations and to gain useful information for the new building projects of the rapidly expanding company.

One of the heat recovery systems on the building roof: Constructed lengthwise for energy-efficient separation of exhaust and inlet air.

Help with the ErP Directive

At the same time as MultiCross was planning the Zalando project, negotiations were in progress regarding the European Union’s 2016 ErP Directive formulating new efficiency requirements for room air conditioning. “That was a problem for us. Because lots of important details tend not to have been clarified even when such directives come into force,” says Reimann. Experience with EU directives shows that the individual points only take on concrete form following practical questions from the industries concerned. In this case, for example, it was for a long time not even definite that a logistics building like Zalando’s would be subject to the new stipulations at all.

Even on extremely hot July days, the temperature in the buildings and aisles now is a pleasant 22 degrees Celsius.

Reimann was faced with the question of how he was supposed to plan his customer’s air conditioning system in conformity with an as yet unknown standard. Being a Premium partner of ebm-papst, Reimann was however able to consult the company on such matters. “ebm-papst always gave me extremely sound appraisals, so that we soon had a reliable basis for planning the Zalando project.”
The logistics center in Lahr went into operation in 2017. And even on extremely hot July days, the temperature in the buildings and aisles was a pleasant 22 degrees Celsius – at all times and in every last corner. 

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