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Data Centers – Where Did All the Water Go?

jack-pouchetI’d like you to start thinking about how much water your data center uses a day, a month, and a year. Not just for personnel, but for the cooling towers, chiller plants and related IT process applications.

Why worry about water? Well, when more than 1 billion people do not have access to safe drinking water and fully one-third of the world’s population lives in “water stressed” countries, it is time for us to seriously rethink our use of water within our data centers. Water is a life necessity that we must carefully guard and protect in order to ensure our way of life.

As a first step, we need a way to measure water usage in terms of productivity. There has been much discussion around measuring energy usage and productivity in data centers. We need a similar discussion for water usage.

So consider for a moment the ideas of Power Usage Effectiveness, a.k.a. PUE, as defined by The Green Grid, as well as the general concept of productivity, where tangible outputs are related to a unit of input. Now let’s take that idea and tie it to water.

Many people feel that water is the next oil. Though that analogy is probably not the best, it helps us understand water’s value as a unit of measure of productivity. By relating output to water input, we can report, measure and improve data centers’ water productivity and water-use footprints.

It is time for the data center industry to formulate a Water Systems Productivity metric (WSP). Take useful work or even a proxy for useful work, such as the proposed Compute Units Per Second, and divide that by the amount of water used during the period. Water may be measured in units, with 1 unit equal to an acre-foot. However, gallons/liters is also acceptable.

This WSP metric would ideally be reported monthly with your other metrics. Once we start to measure and report water utilization, we will quickly realize that simply flowing more cooling water in order to “economize” may not always be the best answer. Now we will be able to have a meaningful tool to determine the ideal mix between dry-coolers, CW plants and evaporative cooling towers compared to the increased energy used with alternative solutions.

Let’s help the EPA, EU, Green Grid, and others drive a water productivity metric suitable for use within the data center community and a reporting system for rewarding Energy Star-type performance levels.

Jack Pouchet is director of energy initiatives for Emerson Network Power.

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4 thoughts on “Data Centers – Where Did All the Water Go?

  1. Your suggestion of measuring water consumption soley against compute power is misguided. Unless it takes in account PUE or power consumption of the mechanical systems it will only lead to inefficiency. Direct expansion cooling systems consume several times more power per ton of cooling than evaporative units. I agree we need to be measuring and tracking water consumption of large (>1mw) datacenters. I believe your suggestion of measuring against compute cycles is self serving as Liebert is not competitive with McQuay, Trane, and Carrier for large deployments.

  2. As it was with PUE, the most immediate value of a metric of any kind is that it gets people to start measuring consumption. If water use is measured it can be managed. I think it is premature, however, to think of this in terms of a productivity metric. The industry is currently struggling with which productivity metric (or proxy) is the best one to use and, until that argument settles out, metrics will be used inconsistently and to game the system. Since the water in question is used to supply cooling, a usable metric will relate water use to either the amount of cooling provided or the amount of electrical power use that is subject to that cooling. Comparing quantity of water used to either the numerator or denominator in the PUE metric would make sense. Gallons of water per watt of power delivered to it’s point of use.

  3. Use of water in data-centres is a very North American centric bad-habit. In EMEA (largely for reasons of the health hazards arising from water towers) we tend to use more air-cooled chiller plant in data-centres. The link between data-centres and health is that a local case of legionella can cause a water tower to be immediately shut down by many local health authorities – not condusive to uptime!

  4. This is an interesting suggestion, but some way ahead of its time. In many geographies and organizations, water use isn’t even metered – that would be a start. Once we have a metric, we would then have a complicated debate – a good metric in power leads to a poorer metric in water, or vice versa. Managers would probably end up with a formula based on financial savings, rather than what is best for the planet or even for the local neighborhood. That isn’t what the EPA or the US intended. Good debate ahead, though.

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