BSRIA study reveals changing technology for data center coolingOctober 2015

Lone Hansen Manager - IT Cable Group

A newly published market study from BSRIA shows that – with the CISCO Cloud Index forecasting – data center traffic will grow at 23 per cent CAGR, reaching 8.6 zettabytes by 2018. The move to off-site data centers is at the heart of this growing trend, however, it is not uncommon for data-critical organisations to retain enterprise data centers on their premises.

Cooling within the data center is a fundamental function of the smooth and efficient operation, however, the cooling equipment is a major share of the cost within the CAPEX outlay.

A combination a of energy efficiency measures and rising energy costs have resulted in companies searching for ways of lowering their PUE (Power Usage Effectiveness) and operating costs. It is especially crucial for the colocation data centers. In particular Big Data companies have been criticised for their inefficiency which is seeing their adoption of newer technologies.

Main types of precision cooling used in data centers

Following amendments in the ASHRAE 2011 (still need to identify that relaxed temperature and humidity requirements for the Data Centers, the cooling segment of the data center market is undergoing some dramatic changes and opened opportunities for a range of technologies).

Figure 1, cooling within the overall costs structure

Traditional close control (CRAC and CRAH) is still fit for purpose in many countries, however, it is gradually losing its share to newer technologies, especially evaporative cooling.

Evaporative cooling capitalises on the feature of water as a natural coolant when warm and dry air is being humidified allowing for significant savings in operating costs. Evaporative cooling can either utilise the pressurised or compressed water mist (evaporative system) or wetted pads media (adiabatic system).

It is also divided into direct (direct external air is allowed into the data hall) and indirect (when external air does not mix with the internal air within the data hall).

Lone Hansen, WMI Manager – I.T. Cable Group, BSRIA, said: “One major downside with evaporative systems is that they consume water (which can itself be an issue if supplies are scarce) and the evaporative process can cause scaling of pipework and heat exchangers in high pressure systems. The products are more suitable for new build projects due to the space and height requirements, as they are mostly large units. The use of water also raises the issue of legionella, which needs to be given consideration in the design and operation of a facility.”

Close coupled solutions embrace a range of products, located close to the heat source: in-row, rack, rear door heat exchangers and overhead terminal units. These are intended to be more expensive and more suitable at higher densities racks.

Liquid (direct on-chip or immersion cooling) cooling is taking the water or other source of heat rejection (Novec 1230) directly to the server. Depending on application and the technology chosen the server equipment can be completely submersed into the coolant. However, there is still a certain stigma around liquids being at the heart of the IT equipment and it still remains a rather niche product, used only to deal with extremely high densities in HPC segment (>35kW per rack).

What are the geographical differences in the use of technology?

Both the UK and the US are major data center users sharing a similar profile for the choice of cooling technology used, however, it is believed that as more applications move to off-site data centers, operators will increasingly be looking for locations in low cost countries, this will drive the use of different technology used in these newer application.

The US accounts for approximately 40 per cent of the worldwide precision cooling market. It is the market with the largest share of the evaporative cooling, representing 26 per cent of the total market.

Figure 2, US – DC precision cooling market segmentation proportions by category, %, 2014


UK has traditionally been a big Data Center market, being Europe’s main banking and financial center. However, recently there has been a move to the cloud and IT companies that are now at the forefront of the Data Center investment in the UK.

Big data companies – industry game changers

With it being claimed that more data has be captured in the last 12 months than the previous 5,000 years, it is big Big Data companies/Cloud providers who are driving the biggest changes. The strategies they are employing for identifying the appropriate locations for their next data centers are not only defined by the cost saving strategies to capitalize on favorable tax regime but also colder climate, allowing them to maximise the use of free cooling.

Figure 3, UK – DC precision cooling market segmentation proportions by category, %, 2014

Within EMEA the popular destinations for Big Data companies have been extended beyond Ireland into Nordics (Netherlands, Sweden, Finland), thus creating new data centers “hot spots” within EMEA. Big Data companies choose a variety of technologies to cool their data centers in a most energy effective way.

How cold is your data?

In June 2015 a study by Jonathan Koomey and Jon Taylor ‘New data supports finding that 30 percent of servers are ‘Comatose’, indicating that nearly a third of capital in enterprise data centers is wasted’ confirmed the view that a great deal of the servers inside the data centers is just consuming electricity while not being used or accessed in any way. The study concluded that the level of these servers, which are called comatose servers, is at 30 per cent of all the servers inside the data centers.

Lone Hansen, WMI Manager – I.T. Cable Group, BSRIA, added: “Identifying that the redundant and rarely accessed data in the public cloud comprise a large share, in 2013 Facebook separated the old data into the “cold storage” category. Cold storage can be defined as the retention of inactive data that an organisation or an individual rarely, if ever, expects to access. Previously it was believed to be necessary for the servers in data centers to be "always on" to provide immediate access to users' data, but the servers in the cold storage facility are on "sleep mode" and kick-start only when there is a request for access archived information.

The server, that stores such data is kept in the sleeping mode and does not require active cooling. It is only switched on, when the data request is sent to the server. There will be a certain delay in accessing data by the end-user but that slight delay is believed to be acceptable.

Facebook has devoted considerable attention to the hardware used for a cold storage system through the Open Compute Project that has been working on the improvements in the hardware systems used in Data Centers, including cooling. It led to adoption of direct evaporative cooling in the Facebook Data Centers and, following some teething problems in 2013, it has been implemented across an increasing number of their storage centers with improved control. In 2014 Facebook also presented the modular approach to cooling in the Data Centers through Open Compute, opening this technology for wider usage in the data centers.”

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