Water Consciousness Continues in the Data Center

is Mission Critical Market Leader, Western Region, at JE Dunn Construction. Ron was previously Director of Mission Critical for Gray Construction and also served in leadership roles with Qwest Communications and Aerie Networks. You can find him on Twitter at @RonVokoun.

Ron Vokoun, GrayRON VOKOUN
JE Dunn

“Water is the new oil.” That is a statement made by a “futurist” at a leadership forum I attended back in 2006. It’s an idea made increasingly popular by Steven Solomon in his book “Water: The Epic Struggle for Wealth, Power, and Civilization.” I am not arguing this political position or debating the accuracy of this statement, but rather using it as a starting point for a conversation on water.

Let that statement sink in for a moment though. To compare water to oil is to say that water is rare, of great value, and something that countries are willing to go to war over. If true, it certainly should be given more attention in our data center discussions.

There is a complex relationship between the use of water and energy in the data center, which will be discussed in my next column. For now, I want to focus on cooling technologies that are proven to reduce the consumption of water, and the availability and alternative sources of water for data center cooling, to highlight the sustainable possibilities that exist.

Water Reduction vs. Resource Optimization

Before diving into the various cooling technologies, it is important to stress that both water and energy consumption can be reduced through the implementation of ASHRAE TC 9.9 for both temperature and humidity. Outside air (OSA) economization should also be a part of any cooling system to take advantage of the free cooling that TC 9.9 enables.

If one focuses purely on reducing water use, technologies such as air-cooled chillers and heat wheels are easy choices that use no water in the cooling process. But if taking a more holistic view, you may pay a premium in the form of increased energy use with these systems.

Evaporative cooling is often assumed to use more water than a traditional water-cooled chiller system, but as is illustrated below, this is not the case, at least in Phoenix.

In many locations there isn’t a single answer for resource optimization. Rather, a combination of technologies to optimize water and energy use while staying within thermal guidelines is best. To illustrate this, as well as water use between technologies, compare the water and energy use for four cooling options in the data below.


Click to enlarge.



Click to enlarge.

As you can see, direct evaporative cooling coupled with either air-cooled chillers or water-cooled chillers uses far less water than water-cooled chillers alone. Air-cooled chillers use no water, but result in increased energy use. And direct evaporative cooling also uses less power than water-cooled chillers. The caveat is that water use and the performance of specific technologies varies based upon location.

These are just a few of the technologies available to reduce your cooling water use. Now let’s turn our attention to the availability of water.

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  1. I agree with this articles suggestion to increase the use of non-potable water for cooling. Unfortunately not every AHJ will allow the use of non-potable or reclaimed (gray) water. As our demand for water increases, I expect that this position will be reversed. Let's save the potable water for drinking.

  2. Mike Mann

    Reclaimed water is commonly used on the scavenger side of "indirect evaporative" cooling of data center loads (e.g. SFR Santa Clara) but most likely not for "direct evap" cooling due to the potential for water-born contaminants being introduced directly into the airstream. Potable water is still a good energy and OpEx reduction option for direct evap data center cooling in many locations and can be managed to optimize "WUE". If data center owners are willing to operate under ASHRAE TC 9.9 Allowable conditions, there are many US locations where compressorized cooling equipment is not needed.

  3. carl

    Air cooled chillers are my first choice over water cooled. Air cooled units are achieving pretty good IPLV ratings now-a-days. Cooling towers are high maintenance, water usage, water chemistry and additives, cleaning and aah not to forget the routine PM and unforeseen repairs.

  4. Lee

    Good comments regarding the importance of water. Current heat wheel technology, specifically KyotoCooling technology, is extremely efficient and has zero water usage. As water becomes more and more scarce, data center developers, users, and designers need to take a serious look at waterless cooling systems.

  5. Rob

    Water management evaluation at the site level will show the opportunity for more integrated stormwater control through reuse. Technology is available to allow for such with many successes throughout the US and points beyond. The Water/Energy Nexus is a complicated one, when considering air cooled equipment has embedded water costs upstream of installation.