DCN May 2017 - Page 25

design & facilities Management If a new approach is understood to have improved efficiency or stability, then it is best to have data to support and substantiate this claim. Continuing to develop first class facilities requires a continual investment in due diligence, research and development and computational simulation. cold aisle of a computer room, with many people still adamant that the servers need to be kept at sub-arctic temperatures, otherwise terrible things will happen. A gold standard for some time for server inlet temperatures has been the ASHRAE Envelopes, recommending inlet temperatures up to 27°C, and allowing up to 32°C. However, as recent research has shown and something ASHRAE readily admit, is that maximising these temperatures is also not the single best way to go. You can – as far as the servers are concerned – go up to these temperatures, and parts of the system will operate much more efficiently because of it, but that doesn’t mean that you should. Importantly, if you consider the system as a whole – cooling, power and IT – then there is a point of optimum operation past which there are inefficiencies. With newer IT systems, perhaps this optimum point will change. Eliminating fans from the servers and instead demanding a minimum pressure different between hot and cold aisles would change this substantially – this is a great example of how a best practice is hard to define in a proudly innovative industry, and is a great example of how continued research allows the best practice to change. Discussion and debate The great thing about this industry is that we are not averse to discussion and to debate. Conversely, we actively embrace it. As data centre designers and operators, we want to make sure that we are continually at the forefront of innovation and best practice, and we acknowledge that a key to this is sharing of knowledge and experiences. This constantly changing, dynamic environment, has one downside which is often not appreciated – confusion. There is so much information about what is right, what is better and what is the best way of doing something that it can be hard to filter the scientific fact from the sales. You rarely get the opportunity to have two differing systems in a controlled comparative test. aligned with the requirements of the equipment, and where opportunities for passive cooling are seized at every opportunity. Similarly, uninterruptible power supply (UPS) systems have developed, and the options available have widened, to align better with the power qualities present, and with the input power characteristics which are required by the systems. Efficiencies in UPSs have developed to be nearly lossless in some conditions. All of this, however, has needed change. It has taken many years for people to change their mindset about the temperature within a May 2017 | 25