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STULZ DFC² Direct Free Cooling for Data Centres

DFC2 from the CyberAir product series by STULZ uses the ambient air to cool server rooms. For this most energy-efficient cooling method STULZ now offers a standardized product with a hinged coil. It delivers reductions in operating costs of as much as 80% and also enables CO2 emissions to be cut substantially.
STULZ DFC²   Direct Free Cooling for Data Centres
Direct Free Cooling Utilising Close Control Air Conditioning
The heat load in server rooms is enormous, and demands continuous cooling. Conventional systems based solely on compressors are very costly. A more cost-effective alternative is offered by the standardized solutions with DFC2 from STULZ, which work according to the principle of Direct Free Cooling. Uwe Kudszus, product manager in STULZ's precision air conditioning division, says: 'DFC2 responds very precisely to changes in temperature, automatically adapting the operating mode as necessary. As long as the ambient temperature is below the required server supply air temperature, Free Cooling is in principle possible. If the ambient temperature rises, the compressor is activated. The system uses exclusively compressor-based cooling only at very high ambient temperatures.' In such cases DFC2 automatically switches to circulating air mode.

Air supply without pressure loss
STULZ is the only manufacturer to offer Direct Free Cooling systems with folding coils. These products prevent pressure losses during air exchange and so make the system even more energy-efficient: 'Fixed coils always pose an obstacle to the air flow. In Free Cooling mode, the pre-treated ambient air flows directly through the A/C unit into the server room. Only in compressor or combined mode is the coil swung into the air flow. Filter units reliably clean the ambient air at all times regardless of the operating mode.'

Predictable savings
The cost of changing over to DFC2 is quickly amortized. An example involving calculations for a data centre in Hamburg demonstrates: Based on an area of 800 square metres, and a heat load of 1 Megawatt, with purely compressor-based cooling costs of around 296,000 Euro a year are incurred. Direct Free Cooling reduces that cost by 262,000 Euro to around 34,000 Euro a year1. 'To aid costing when planning A/C systems we have created temperature profiles for the world's major cities,' Uwe Kudszus reports. 'A data centre in Hamburg, for example, can do without compressors entirely for 95 percent of the time. Even in warmer climates, such as in Madrid, the compressor would be left off for 72 percent of the year.'

Intelligent system monitoring
Intelligent system control is essential in order to make maximum use of energy resources. DFC2 makes it easy for users, because the tried and proven microprocessor C7000 monitors the complete system. Once integrated into the existing building services management system, all active components - from the A/C unit, through the coil, to the humidifying system - can be centrally controlled.

Modular design for flexible solutions
STULZ DFC2 products are available as water- and air-cooled systems, in three sizes for each. Users are able to choose from standardized modules which they can combine as required to create custom system solutions.
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