© 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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