Worthwhile cooling solution for data centers

As a result of the constant progress in digitalisation, such as cloud computing, the demand for greater computing power continues to grow.

In order to meet this demand reliably, the construction of additional, increasingly larger data centres - in some cases covering areas of over 5,000 square metres - is essential.

The high-performance equipment in these centres can produce up to 30 kW of heat per rack (cabinet for storing IT hardware). In order to maintain the operating temperature at a constant level and therefore avoid overheating of the systems, continuous and reliable cooling is imperative. The air-conditioning of data centres is an operational necessity in terms of server reliability and availability.

Cooling systems comprise ventilation, air distribution and cooling and, depending on the system used, air conditioning may account for up to 50% of the total energy consumption, in particular in smaller data centres. For this reason, large data centres are mainly built in countries with lower electricity prices such as the Netherlands or Sweden. And for countries with comparatively high electricity prices, such as Germany, smart energy strategies are thus in demand to reduce energy consumption and increase competitiveness.

The optimal cooling solution for each rack

There are many different ways to cool a server room, and these vary depending on the size of the data centre and the number of racks. Air cooling is typically used in particular for small and medium-sized data centres (500 - 5,000 sqm). The air is cooled down with the help of a recirculating air cooler and is then fed to the racks via pipes into an intermediate space underneath the floor.

With regard to energy efficiency, cold and hot aisles provide excellent results. If there are several rows of racks, it is advisable to place these in such a way that the front and rear sides of the racks are facing each other. The temperature-controlled air is blown into the cold aisles only. The IT equipment absorbs the cold air as a result of which the entire system is cooled down, which in turn releases the heated air into the hot aisle. The warm air is then drawn in again by the recirculating air cooler and the cycle starts again.

In order to prevent cold and warm air from mixing, the cold aisles should be enclosed, for example with glass. This means that the need for cooling can be reduced by a further 30%. The supply air temperature in the cold aisles should be between 18 °C to 27 °C and relative humidity should be a maximum of 60% (dew point between 5.5 °C and 15 °C).

In countries with low average temperatures, such as northern Sweden or Finland, either direct cooling, with cold air from the outside, or an indirect cooling with water pipes, whose medium is cooled in the outside area, is usually also added. Cooling down by means of cooling units is only necessary if the outdoor temperature is too high. This naturally leads once again to a further reduction in energy costs.

If a heat dissipation of 25 kW is exceeded, air cooling is no longer sufficient and water or refrigerant cooling is recommended, as these media absorb the heat much better than air. In this case, either heat exchangers are placed in the immediate vicinity, next to or underneath the racks, or air conditioners are used directly inside the cabinets. For the former, a comprehensive infrastructure of cold water pipes must be devised.


Save more with Kaiflex

The insulation of cold running pipes should be an essential element of any data centre air conditioning and ventilation concept for the following reasons:

1. Increased reliability
For all pipes carrying both cold liquid media and air, the same applies: Efficient insulation is an essential requirement for making the entire system reliable and for maximizing energy saving potential. Whenever the temperature in the pipes or air ducts is below room temperature, condensation occurs. Condensation, on the other hand, leads to corrosion and rust in the long term, and therefore to irreparable damage to the pipework. The servers in these centres run on a 24/7 basis throughout the year and therefore require permanent, fail-safe cooling. If the pipes and air ducts leak, this inevitably leads to an exchange between the pipes and air ducts and as a result to an impaired cooling, which has a devastating effect on the computing power of the data centre.

This weakness can be effectively avoided with Kaiflex insulation materials. Thanks to its closed-cell structure and water vapour diffusion resistance of up to μ ≥ 10,000, the rubber insulation material is resistant to moisture. Even damage to the surface does not impair the water vapour barrier.

2. Reduced energy losses
Due to the high cost of cooling data centres, all the necessary measures must be taken to ensure that as much of the cooled air as possible reaches its destination. Kaiflex insulation materials ensure a constant temperature in the cold water pipes and air ducts. The thermal conductivity of up to λ0 °C = 0.033 W/ (m·K) ensures that no energy or temperature is lost on the way from the air conditioner or outdoor area to the racks.

In some countries, the dissipated waste heat is not fed back into the air-conditioning units, but sold as waste heat to district heating networks. In this case, insulation with Kaiflex ensures that as much of the produced heat energy as possible reaches the buyer.

3. Protection of IT equipment
The IT equipment is sensitive and must be reliably protected from dirt. Closed-cell Kaiflex insulation materials are entirely safe to use within the server rooms as these are free of dust and fibres.

(1) Operationally safe data centre - Guidelines, BITKOM (German)
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