Energy efficiency
Taking the heat out
Is it better to keep servers cool, or simply to remove the heat? Matthew Philo, product manager CRAC at DencoHappel, explains what the difference is, and explores how HVAC professionals can help to advise data centre managers on the best solution for them.
W
e all know how important it is to keep servers and other computing machinery at the right
temperatures, but what is the best way of doing so? For many years people thought that keeping the equipment ‘cool’ was essential, but the mentality of ‘heat removal’ is becoming increasingly popular. Data centres have rapidly altered how they approach temperature control in recent years, with a marked migration from using cooling to heat removal techniques. Much of this comes down to an increased understanding of the temperatures that computers and servers can deal with as well as advances in the technology itself. When we look back at when data centres
were first established, the machinery used required computer scientists working at their desks side by side with the machines. It was important to keep the machinery at a reasonable temperature, while ensuring that the room was suitable for these specialists to think clearly, too. In order to provide a suitable
environment, the whole room was typically maintained at a temperature of around 21°C. Further to this, the relative humidity had to be kept at around 50%, to ensure high quality paper operated through the machine could be stored appropriately. That often resulted in the
cooling system supplying air at as low as 11°C, to keep the whole room around the 21°C target. This old notion of ideal temperature and humidity range has remained much longer than the technology inside a data centre itself. Datacentres nowadays are mostly
occupied by technicians rather than data scientists, reducing the need to maintain an ideal temperature. With the development of aisle containment, it means that the cooling systems can now provide air at mid-20°C temperatures, without affecting server performance.
With these elevated temperatures, maintaining the separation of the airflows is key. By preventing air going into the server and mixing with air exiting the hardware, you can focus on containing the hot air in ‘hot aisles’. Without the containment, you need to affect all the mixed air within the room, which is an inefficient way to maintain temperature evenly within a data centre. Nearly all the electrical energy going into a
data centre will eventually become heat and we now have a better understanding of aisle containment and optimum datacentre layout. We do not need to make a datacentre into a fridge. Instead, it is more effective and efficient to capture and remove the heat produced from server. By thinking in this manner, data centre managers
Above: An engineer works on a MultiDenco Display which exploits free cooling by using a water circuit as a go-between when the outdoor air is colder than the indoor conditions
can decrease the facility’s Power Usage Effectiveness (PUE) ratio whilst maintaining a suitable environment for IT hardware. In fact, modern cooling systems that capitalise on this philosophy will often pay for themselves very quickly when compared with more traditional technologies. DencoHappel’s indirect evaporative
cooling system, Adia-DENCO for example, exploits the temperature difference between the indoor and outdoor environment, by passing the indoor and outdoor air through a plate heat exchanger. With warmer outdoor temperatures, it can utilise adiabatic humidification to continue the heat rejection.
Alternatively, the Multi-DENCO F-
Version exploits free cooling by using a water circuit as a go-between when the outdoor air is colder than the indoor conditions. With higher indoor temperatures, it extends its mix-mode, where both the free cooling and the direct expansion operate simultaneously. The system benefits from the ‘cube root’ principle, where if the free cool circuit can provide 20% of what is required, then this is 20% less for the direct expansion circuit, saving near 50% in energy consumption. Thinking ‘heat removal’ is an energy
Matthew Philo, product manager CRAC at DencoHappel
efficient way of maintaining a datacentre that can help to save your customer money on their running costs. For this reason, as well as the rise of technologies such as adiabatic evaporation and free cooling, it is rapidly increasing in popularity and offers an effective alternative mind-set to traditional ‘cooling’ techniques.
WEATHER LOUVRE
RANGE Design – Supply – Installation call us on 01457 861 538
www.heatingandventilating.net email us at
sales@gdl.co.uk
WEATHER LOUVRES | ACOUSTIC LOUVRES | LOUVRE DOORS PENTHOUSE LOUVRES | PLANT SCREENS | GLASS SYSTEMS
November 2017 35
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