Google's Chiller-less Data Center

The equipment yard at the Google data center in St. Ghislain, Belgium features no chillers. (Photo from Google)

The equipment yard at the Google data center in Belgium features no chillers. (Photo from Google)

Google (GOOG) has begun operating a data center in Belgium that has no chillers to support its cooling systems, a strategy that will improve its energy efficiency while making local weather forecasting a larger factor in its data center management.

Chillers, which are used to refrigerate water, are widely used in data center cooling systems but require a large amount of electricity to operate. With the growing focus on power costs, many data centers are reducing their reliance on chillers to improve the energy efficiency of their facilities.

This has boosted adoption of “free cooling,” the use of fresh air from outside the data center to support the cooling systems. This approach allows data centers to use outside air when the temperature is cool, while falling back on chillers on warmer days.

Google has taken the strategy to the next level. Rather than using chillers part-time, the company has eliminated them entirely in its data center near Saint-Ghislain, Belgium, which began operating in late 2008 and also features an on-site water purification facility that allows it to use water from a nearby industrial canal rather than a municipal water utility.

Year-Round Free Cooling
The climate in Belgium will support free cooling almost year-round, according to Google engineers, with temperatures rising above the acceptable range for free cooling about seven days per year on average. The average temperature in Brussels during summer reaches 66 to 71 degrees, while Google maintains its data centers at temperatures above 80 degrees.

So what happens if the weather gets hot? On those days, Google says it will turn off equipment as needed in Belgium and shift computing load to other data centers. This approach is made possible by the scope of the company’s global network of data centers, which provide the ability to shift an entire data center’s workload to other facilities.

In a March interview, Urs Holzle, Google’s Senior Vice President of Operations, said the company typically uses manual tools to manage data center level outages and downtime.  “Teams regularly practice failing out of or routing around specific data centers as part of scheduled maintenance,” he said. “Sometimes we need to build new tools when new classes of problems happen.”

Redirecting Workloads Instantly
At last month’s Structure 09 conference, Google’s Vijay Gill hinted that the company has developed automated tools to manage data center heat loads and quickly redistribute workloads during thermal events (a topic covered by The Register). 

“You have to have integration with everything right from the chillers down all the way to the CPU,” said Gill, Google’s Senior Manager of Engineering and Architecture. “Sometimes, there’s a temperature excursion, and you might want to do a quick load-shedding to prevent a temperature excursion because, hey, you have a data center with no chillers. You want to move some load off. You want to cut some CPUs and some of the processes in RAM.”

Gill was asked if this was a technology Google is using today. “I could not possibly comment on that,” Gill replied.

Look Ma: No Chillers!
But Google engineers had already disclosed the existence of the chiller-less Belgium data center at the Google Data Center Efficiency Summit in April in Mountain View, Calif. At the event, we asked specifically: are there chillers on-site that are rarely used, or no chillers at all?

The answer: no chillers at all. The facility will rely entirely on free cooling, and redirect workload on days when it’s too hot to operate. This approach makes local weather an issue in network management, although advanced forecasting can help Google anticipate days when it may need to divert work from the Belgium facility.

Nonetheless, even Google is periodically challenged by rerouting entire data centers, as seen in a February Gmail outage when a data center was overloaded while shifting workloads. Traffic redirection was also an issue in a brief outage in May.      

An Enabler for “Follow the Moon”?
The ability to seamlessly shift workloads between data centers also creates intriguing long-term energy management possibilities, including a “follow the moon” strategy which takes advantage of lower costs for power and cooling during overnight hours. In this scenario, virtualized workloads are shifted across data centers in different time zones to capture savings from off-peak utility rates. 

This approach has been discussed by cloud technologists Geva Perry and James Urquhart as a strategy for cloud computing providers with global data networks, who could offer a “follow-the-moon” service to enterprise customers who would normally build data centers where power is cheap. But this approach could also produce energy savings for a single company with a global network – someone like Google.

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About the Author

Rich Miller is the founder and editor at large of Data Center Knowledge, and has been reporting on the data center sector since 2000. He has tracked the growing impact of high-density computing on the power and cooling of data centers, and the resulting push for improved energy efficiency in these facilities.

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  1. Try moving the petabytes that go with an enterprise data center out of Belgium. It's OK for Google but not a universally viable solution in the enterprise. Bottom line is we need to reduce the deltaT (difference in temperature) between ambient outside and Tcase - (the chip case temperature). Air can't do it above 35 degrees C (thats 100 F). Liquid can work up to 45 degrees C (120 F) ambient with free cooling - no refrigeration. A small UK based firm - Iceotope just filed all the patents on how to do it cheap and repeatable. Beta build started. Steve

  2. Sump Pump

    A data center in Antarctica with a sufficiently large fiber link is inevitable. There's no precipitation. Just leave the roof off and you've got all the cooling you'll require.

  3. precipication...except for global warming.....bye bye to the data centres.... :) hey..wait my data center is under water now.....albeit,....really really cold!!!!!! probably colder than needed....and more wet than needed as well...

  4. Skaperen

    Places like Antarctica and Greenland don't have sufficient cheap power. However, Iceland is a nice cool place and it does have lots of cheap geo-thermal power. And it's situated where it could cabled up to both North America and Europe.

  5. michael p

    Latency to antarctica would be pretty high. As well as rerouting traffic to the datacenter to half way around the world to chase the night.

  6. Lennie

    "Follow the moon ?" I don't think it's something they can/would do. My guess is they want the data and applications close to the user because of latency. If you follow the moon, generally speaking, you'll not be where the users are awake (I presume most people sleep at night).

  7. michel

    Maximum 71 degrees in Brussels ? I hope they calculated a margin AND they should fire the guy that told them that.. we had more then 10 days of 86 degrees + already and the summer has just started...

  8. Bob

    Maximum temp in Brussels 71 F (22 C). Nonsense. The site linked to shows that as the *average* maximum temperature. I've seen temperatures in Brussels get to 36 C (97 F).

  9. LFM

    Plus the moon isn't always up at night. it can be up at any time. Yes, it obvioulsly needs the data to be replicated but google does this all the time so no big deal. Many other people havn't figured out yet that data storage is cheap and you can store it multiple places just in case you want to work somewhere else.

  10. JLE

    I'm not buying it. Google has the luxury (Money) to test and implement these "Fringe" concepts, even the largest enterprise providors wouldnt consider this option. History has shown that for every one ingenious idea Google comes up with, there are 10 questionable ideas. And thats just the ideas we actually hear aboutThis is one of the bad ones.

  11. Quite a nice interesting fact!

  12. quite interesting... itd be even more interesting to see what google has planned for its floating datacenters for the ocean which use sea water to cool....

  13. Mr. Externalization

    If Google transfers workload by following the moon, they will be externalizing the power costs onto the network. The routers local to the user will still be located in the hot (daytime) regions. Given the potentially long route to the active data center, does this really save total search power from user entry to response?

  14. the idea of "follow the moon" is very interesting. It seems in big frame of "back to nature" ideas campaigned by environmentalist a decade ago.

  15. Trip Edgerton

    Anchorage, Alaska would have a nice temperature profile for one of these.

  16. Hamranhansenhansen

    The key thing here is that this is not 1 data center, it's 1 node in a global network of data centers. So they can plan to shut down this node if it needs artificial cooling because they have other nodes. Even when you have a very hot day it is only too hot during certain hours, not all day. Google is working an order of magnitude up from most technology companies. So sometimes the stuff they're doing doesn't make sense until you look a few years out. They are thinking on another scale. They have math that shows that there isn't enough energy in the world for them to do the things they want to do on the scale they want to do them using the same old methods.

  17. Warm Data Center

    The thought is good in concept, however what they may save in cooling costs, surely goes back into dehumidifiers? I believe that I also agree with the posts, that 71degress is well below the average daytime summer temperature for Belgium. Definitely a step in the right direction however.


    86 Deg.??? what is the Wet Bulb Temp? or Relative Humidity?