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We’ve been talking for years about conserving energy in data centers, and justifiably so, but more recently the idea of conserving water has been gaining attention as well. Saving water saves money but in some cases it’s also a practical matter, because water is in short supply. In any case, conserving any natural resource is simply the right thing to do.
The good news is there are steps you can take that are either free or inexpensive to save considerably on water use. In this post, we’ll identify three of them, along with a couple of others that are more expensive but may be worthwhile for larger data centers.
1. Raise the temperature. As we’ve mentioned before, in 2008 the standards setting body ASHRAE changed its guidelines around recommended data center temperature, raising the upper end from 77 degrees F to 80.6 degrees F. Many air conditioning systems, especially those used in larger data centers, use water as their heat rejection medium. The cold water supplied to the air conditioning system comes either from a chiller or cooling tower. The amount of water required to remove heat from the data center will vary depending on the air temperature required. If the air temperature is increased, the air conditioning system will require less water or can get by with elevated water temperatures. So raising the data center temperature, and thus easing the burden on your cooling infrastructure, will reduce your water usage and save energy.
2. Increase the humidity. If you’re worried that increasing the temperature will also increase the humidity level in your data center, don’t. ASHRAE also widened the band for recommended moisture levels in a data center, enabling companies to raise the relative humidity levels. Five or 10 years ago, every specification for a new data center said the goal was to maintain 50% relative humidity. The new guidelines say data centers can go up to 60% relative humidity with no ill effects.
3. Seal up the data center. One of the easiest things you can do to ensure temperature and humidity levels stay where you want them is to ensure your data center is well-sealed. If your data center is not well-sealed, you’re forcing temperature- and humidity controlled air out – air that has to be replaced with more controlled air. Sealing a data center is a relatively inexpensive endeavor. It just means ensuring you close up or seal any areas where leaks may occur, such as in ceilings, cabling and piping penetrations through walls and where walls meet floors.
4. Use economizers. This one isn’t quite as cut and dried but the use of economizer mode on air conditioning units – basically using outside air to help cool the data center – can also lead to reduced water use. The reason is that economizer mode reduces energy consumption and it takes water in some way, shape or form to produce energy. Think about nuclear power and how water is used to cool the fuel rods. So it may not be your own water use, but somewhere along the line economizers will save on water use. (As a side note, this is a problem with the Water Usage Effectiveness metric published by the Green Grid. It takes into account only your own water use, not the water used in the energy your data center consumes. So it’s a bit flawed, from my perspective.)
5. Use recycled water. Using the same water over and over also conserves water, although the water does have to be treated. There are different ways to do that, including certain chemical processes that break down the bacteria and such to get the water to acceptable levels. Or you could go the Google route, as Data Center Knowledge reports:
Google is notable among industry companies for its steps to reduce water usage. Two of its data centers run entirely on recycled water (as does Microsoft’s San Antonio data center). Google also uses water from a nearby industrial canal to cool its data center in Ghislain, Belgium. The company has built a 20,000 square foot water treatment plant to prepare the canal water for use in its nearby data center.
Granted, not many data centers are large enough to warrant their own water treatment plants. But reducing water consumption is an attainable goal in virtually any data center.
