Cutting costs for IT cooling

Expert advice from Rittal for data centre cooling

The energy needs of German data centres are set to rise to 16.4 billion kWh by 2025 due to the growing use of IT systems, according to the Borderstep Institute. Faced with high electricity costs, it is becoming increasingly important for companies to cut energy spending in data centres. One of the major factors determining operating costs is cooling – depending on the IT system’s overall efficiency, up to one third of the energy supplied may be for climate control technology. A water-based cooling system for medium and high output classes of up to 40 kW per rack offers high potential savings for running costs if implemented correctly. The following article shows what’s important in this process.

Anyone who currently operates only a few IT racks but anticipates major expansion of the IT environment may need to change over the climate control concept completely. For example, this may involve switching from rack-based individual cooling with refrigerant-based systems to a solution that works with suite cooling and enclosure of IT racks and uses a water-based cooling concept.

The focus should be on the high energy efficiency of the overall system. Rack-based cooling generally offers the best energy efficiency. With this solution, the IT rack and cooling unit form a sealed unit. This also enables cooling of high loads of 40 kW per rack although the purchase costs are comparatively high.

Suite cooling uses the principle of containing enclosure suites by partitioning the areas in front of and behind racks into hot and cold isles. This helps increase efficiency. Conventional room cooling is less efficient in comparison, as it involves moving large volumes of air.

Tips for aisle containment

Users who opt for aisle containment don’t always have to completely redesign their data centres. Retrofitting solutions are also available for established IT environments. As well as their standard systems, manufacturers such as Rittal offer special aisle containment systems to integrate elements such as various high racks and customer-specific factors including pillars, joists, fire extinguishing equipment and lighting. Basic requirements such as hot and cold aisles, a cold aisle alone, aisle widths, escape routes and door opening angles are also taken into account.

Fitters carry out measurements on site and then develop a customised solution. Overall, aisle containment is worthwhile for any IT environment in the medium and low output range, as the energy costs for climate control are cut significantly in the long term.

When selecting a supplier, companies should obtain a solution that is entirely from a single source. This is the only way to ensure all elements of the aisle containment and cooling system are coordinated with each other. If elements don’t fit together neatly, the cooled air escapes and the system becomes inefficient.

IT managers should also make sure that only flame-retardant and high-quality materials are used for the containment. Experts advise against a do-it-yourself approach in this regard.

Simulation ensures greater certainty

Theoretical planning doesn’t always give clear answers on how new cooling systems behave in existing IT infrastructures. A simulation of airflows in the data centre using special software (computational fluid dynamics, CFD) ensures greater planning certainty. This gives customers precise information on thermodynamic behaviour and heat distribution based on a customised 3D simulation. Developers can thus reliably identify any heat pockets in the data centre and also see the impact of failures of individual climate control systems. A CFD simulation is particularly useful if changes in established IT infrastructures are due. As a rule of thumb, the more complex the data centre structure, the more useful the results of the flow simulation. However, this type of simulation is time-consuming and is more worthwhile for larger IT environments. Yet the resulting planning certainty reduces the risks significantly and helps the Management Board reach a sound decision for an IT project based on solid arguments.

Implementing the solution

The Liquid Cooling Package LCP Inline CW solution from Rittal is a good example of a compact water-based cooling solution that enables straightforward suite cooling. An air/water heat exchanger unit is installed right next to the IT racks. The warm IT waste air is extracted at the rear of the unit, cooled and then blown into the cold aisle at the front. Maximum efficiency and, as a result, reduced operating costs are achieved in combination with an aisle containment system. LCP Inline units with water as a coolant enable cooling outputs of up to 55 kW. Units with refrigerant as a coolant can be used for cooling outputs up to 12 kW.