As the cost of electricity increases, the subject of energy efficiency is becoming ever more important - not least for data centre operators. Now, with the new CyberAir 2 series of precision air-conditioning unit from STULZ, air conditioning in data centres can be more energy-efficient than ever. And with a high capacity, too: depending on the type of unit, the cooling capacity ranges from 18.6 kW to 54.4 kW with one compressor, and from 41.7 kW to 72.6 kW in units with two compressors. Up to 31 of these units can be linked and controlled in a network by means of the BUS system.

Less energy consumption with Dynamic Free Cooling
Dynamic Free Cooling, or DFC for short, was newly developed for the CyberAir 2. The electronically controlled hybrid cooling system combines dynamic compressor cooling and free cooling in a total of four stages. DFC automatically searches for the most efficient mode: if the outside temperature is low, DFC reduces running costs by utilising the indirect free cooling system, whereby the compressors remain switched off. As the outside temperature rises, the electronics initially get the system working in an optimally enhanced free cooling mode. If the temperature rises further, the available compressors are progressively switched on. This means that in Amsterdam, for example, cooling purely through compressor operation only takes place on approximately 5 days of the year. Overall, the automatic air-conditioning system ensures precise and efficient interior climate control, for example by controlling the speed of the fans and the electronic expansion valve. Furthermore, DFC balances all active system components in an energy-saving partial load mode. Taking Amsterdam as an example, the comparison of a pure compressor cooling system with the CyberAir 2 hybrid air-conditioning system clearly illustrates the potential savings: for a data centre with a cooling capacity of 200 kilowatts, the capital investment required for the DFC version of the CyberAir 2 is initially 60 percent higher than that for a conventional compressor cooling system without free cooling. However, this additional investment is offset within just two years. Over a running time of ten years and at energy costs of 13ct/kWh, the CyberAir 2 achieves total savings of 356,000 euros.

A varied choice of options
In addition to the hybrid version described above, STULZ also offers further versions of the CyberAir 2 series: A, G, CW, ACW, GCW and CW2. CyberAir 2 units are available in five sizes. They require floor space 1000 mm to 2550 mm wide and only 890 mm deep. The planner has a choice of three coolants: R407C, R410A and R134a. As well as the cooling function, the CyberAir 2 also offers the option of energy-saving refrigerant heaters and steam humidification. What’s more, thanks to its full front access and standardised, defined area for all connections, the CyberAir 2 series is also especially maintenance-friendly. CyberAir 2 units promise maximum reliability, even in a crisis: the CyberAir 2 automatically mobilises the backup air-conditioning units and provides immediate notification of the current maintenance status via SMS or e-mail.

STULZ the natural choice
Since it was founded in 1947, the STULZ company has evolved into one of the world’s leading suppliers of air-conditioning technology. With the manufacture of precision air-conditioning units and chillers, the distribution of air-conditioning and humidification systems, the construction of air-handling plant together with service support and facilities, this division of the STULZ Group achieved a turnover of 200 million euros in 2005. STULZ employs 1,200 workers in Germany and in ten subsidiaries (in France, Italy, Great Britain, the Netherlands, Poland, Spain, China, India, Australia and the USA). Furthermore, the company co-operates with sales and service partners in more than 75 other countries, and therefore boasts an international network of air-conditioning specialists. It has production plants in Germany, Italy, the USA, China and India. The STULZ Group employs around 3,300 people world-wide, and achieved a turnover of over 600 million euros in 2005.