Is free cooling the way forward? Is climate change affecting the data centre? Are advances in server and storage technology leading to a rise in temperature in the data centre? Mark Parnell-Hopkinson, the managing director of Sentronex, investigates

The combination of technical advancements, environmental change and rising energy costs has led to a significant increase in enterprise-level data centre investment. One of the main ways the industry is making improvements is with the installation of new and improved HVAC systems that control the temperature, humidity, air flow and air filtering in a data centre.
Sentronex, an IT services provider to London’s financial community, has recently completed a four stage refurbishment programme at the data centre in Romford. Improvements include a new air conditioning system which uses the latest, free air cooling technology and works with Mitsubishi CRAC units to improve energy efficiency.

Having experienced the different stages of the installation, from planning and implementation, to evaluating the effects this technology has had on how our data centre runs, I want to look at the benefits of this system whilst also highlighting any concerns to take into consideration.

Heat: There is an increasing amount of consolidated, high density storage and server kit to enter the market. A product of this is that in certain areas of a data centre, additional heat loads are created. As a result, any systems that can help to improve both air flow and cooling capacity are welcome.

A traditional way to do this would have been to add more down flow units but with corresponding costs for external condensers, a free air cooling system is the better option for solving both issues. The technology provides additional air flow, which in the UK makes use of our cool to temperate climate, and does substantially reduce the cost of regulating the temperature in a data centre.
Free air cooling technology can even work during warmer periods of weather. Providing the air it brings in is cooler than the return air going into the down flow unit, a free air cooling system will still come into operation and therefore be of benefit.

Cost: There are a number of different ways of installing free air cooling technology. Investing in separate systems and linking them together from a control perspective, can actually be a relatively low cost solution. Free air cooling does not need to be a brand new, from the ground up installation; it can be a supplemental system. This is what we have done at Sentronex.

Space: Within a data centre, it is important to be economical with space when trying to maximise hosting capacity. Typically, free air cooling units take up much less space than a standard down flow unit. In addition, the technology benefits the down flow units; by adding a free air cooling system, down flow units work less and can be left to condition the air rather than cool it.
Environmental: Inevitably, installing free air cooling technology contributes to helping the environment. By using less energy, you are not only driving costs down, but you are reducing the carbon footprint of a data centre. In addition, any savings made through an eco-friendly air cooling system will ultimately mean price reductions are passed on to those clients benefiting from hosted services.

Considerations: Despite having a number of very clear, important benefits, there are still some factors to consider when choosing whether or not to install an air cooling system at a data centre.
Pipe work: Piping is required to allow external air to enter the down flow units so that they can properly condition the air. This is fairly inexpensive in terms of installation and running costs but it could be a space constraint depending on the design of the data centre and what other services are already running in ceilings or under floor. In most data centres, this is something that could be overcome relatively easily but it is still a consideration.

Location: With a free air cooling system, you are drawing in a lot of air from the surrounding environment. If a data centre is in an inner city location or the system is being operated during the summer months and it is particularly hot, the amount of dust that enters the data centre is likely to increase. To ensure particulate matter from outside is not contaminating the data centre, a slightly higher maintenance schedule may be required, in terms of filter replacement and general operational checks.

Is HVAC the future? During the first full month that the Sentronex system went live, a period when we were experiencing high temperatures in the UK, we saw a 50% reduction in electricity usage for our cooling system. Now that the external temperatures are much lower, we are expecting to see even more of a saving, somewhere in the region of an additional 10-20% throughout winter. The fully integrated air cooling system we now have, will also give us the ability to add free air cooling units in the future, without having to increase the number of down flow units in operation.