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Significant change is underway in how we cool our data centers, one that data center owners and operators would do well to pay attention to. An ever-increasing amount of government regulation on compressed refrigerants, the types used in direct expansion (DX) cooling systems today, is paving the way for a variety of new refrigerants to come into use – and not without consequence.
The ban on Hydrochlorofluorocarbons (HCFC) refrigerants like R22 (Freon) started in the US with the phase-out on new equipment in 2010, and a complete ban by 2020 because it damages the ozone layer. While replacement Hydrofluorocarbons (HFC), so-called f-gas refrigerants, such as R134a and R410a do not deplete the ozone they could apparently soon see the same fate due to their global warming potential (GWP). European countries such as Switzerland, Netherlands and other European countries are already regulating even these newer refrigerants and the US, UK, and others are likely soon to follow.
Which brings us to yet another generation of refrigerants known as Hydrofluoroolefin (HFO) refrigerants such as R-32 and R-1234ze. While these address the global warming impact and environmental concerns of earlier generations of refrigerants, they bring another issue: they’re flammable. Under normal operating conditions that’s not necessarily a concern – after all, many of us heat our homes with oil or gas, both of which are flammable. But should things go awry, it does raise the possibility of a flammable liquid or gas escaping into a data center and, should it be ignited by any kind of spark, causing a fire.
This is not mere “the sky is falling” thinking. ASHRAE takes the issue seriously enough that it is coming out with new classes of flammability ratings to cover these refrigerants. Likewise, various standards committees are working on regulations around the safety and handling of these materials.
As we look at these new refrigerants being regulated into use it begs the question as to whether or not typical DX computer room air conditioners will be the equipment of choice in data centers of the future. As manufacturers implement refrigerants like R-32 they are creating systems that introduce risk with fairly high flammability. There are other options like R-1234ze and others which is a blend of R-32, and slightly less flammable. The cost of that, however, is typically that the refrigerant is less effective. So your risk of fire goes down along with the overall performance of the cooling system (which of course means cooling costs go up).
All of this should get data center operators thinking about whether they really want these sorts of refrigerants coursing through their data centers at all. So in the future a better approach may well be to use chilled water or central air handling systems where the refrigerant remains outside the data center.
Of course many data centers use such systems already today, including air economizer systems that use outside air to cool data centers. Now, some manufacturers make economizer systems that also employ refrigerants. So you get the benefit of economizer mode cooling, but also the risk that could come with these new breeds of refrigerants.
It makes more sense to keep these refrigerants out of data centers. For years, air and water economizer cooling systems have been bringing significant benefits to data center owners, reducing their costs while helping reduce their carbon footprints.
And such systems have been doing this without the risk that these new breed of refrigerants bring to data centers. It’s clear to me that using such refrigerants is a risk you don’t have to take.
For even more information, take a look at our free white paper, “Economizer Modes of Data Center Cooling Systems.”
