Increased efficiency through equipment tuning

Whenever I think about Data Centers, my thoughts immediately turn to energy efficiency. In this era of constantly rising energy costs and the ever greater need for data transfer and storage, demand for Data Center capacity continues unabated around the world.

In order to cope with Data Centers' hunger for energy, ever more efficient servers and other IT components are being developed. Data Center infrastructure such as cooling, power supply and distribution are also becoming increasingly efficient. In the field of air conditioning technology - one of the biggest energy consumers in a Data Center beside the servers themselves - considerable strides have been taken regarding efficiency in recent years. Today Free Cooling, either Direct or Indirect, is now commonplace in large Data Centers.

But what about the thousands of smaller and medium-sized Data Centers, which typically use cheaper DX precision air conditioning units? The good news is that these units can also be tuned simply and inexpensively, enabling efficiency to be increased. These units generally have a depth of approx. 900 mm. A mere 50 mm extra unit depth can make a huge difference to efficiency.

Here's an example:

A Data Center with a heat load of 200 kW is to be equipped with two simple air cooled 100 kW air conditioning units, plus a third unit for the purpose of redundancy.

The decision is made to install an ASD 1072 A from STULZ with a depth of 890 mm. The fan power consumption is 4.6 kW, which equates to annual running costs of 4.6 kW x 8760 hours x € 0.15 = € 6,000, just to operate the fans.

But if we now additionally install the high-efficiency rear panel, available as an optional extra, we can reduce the fan power consumption to 4.3 kW, simply by having 50 mm more unit depth. The annual running costs fall to 4.3 kW x 8760 hours x € 0.15 = € 5,650. So we have already saved € 350, or 6 %.

Due to the lower running costs, in just a few months we have achieved a return on our minimal additional investment for the high-efficiency rear panel. The high-efficiency rear panel can be dismantled without problem in order to get it into the building.

The high-efficiency rear panel works like this:

The fan inside the air conditioning unit sucks the air through the filter and heat exchanger. The high-efficiency rear panel enlarges this area of suction. This reduces the pressure drop, and the fan can move the same volume of air with less drive power. Unit depth cannot be enlarged infinitely to reduce the pressure drop, however. 50 mm of additional depth is the ideal happy medium between a larger unit depth and lower fan power consumption. This is backed up by intensive research.

Moreover, efficiency tuning is not just effective for air cooled air conditioning units, but works just as well for dual-fluid units and models with Indirect Free Cooling. With the high-efficiency rear panel, they all become even more efficient than they are already.

About the author

Benjamin Petschke was born in 1969 in Germany. After studying physics he joined STULZ in 1996 and worked since then in the R&D, Export and Marketing department on different positions. With 19+ years’ experience in the Data Center cooling industry, Mr Petschke is specialised in Data Center cooling design, energy saving and acoustic issues.

He works closely with the Joint Research Centre of the European Commission for the Code of Conduct on Data Centres on the Best Practice section and recently with the German DKE in development of the DIN EN 50600, Information technology – Data Centre facilities and infrastructures.

Mr Petschke authored White Papers on subjects like Best Practice for Data Centre Cooling and Indirect Free Cooling with Dynamic Control Logic.