Giant flagship data centers are actually more energy efficient than small computer facilities, Mikko Pervilä says.
Traditionally, computers have been cooled down with mechanical ventilation, resulting in additional electricity consumption. Many other maintenance systems associated with servers also require electricity. In addition to the energy spent on computing, this extra electricity negatively impacts the data centers' energy efficiency. Cloud services have proven to be so financially lucrative that the additional energy use has been considered an acceptable expense in relation to the value of the services.
Energy efficiency has become more of a focus lately from both an environmental standpoint and a financial one, as the price of electricity implies significant savings associated with lowered energy consumption. To maintain reliability, improving energy efficiency cannot result in service interruptions or lags for the end users.
Mikko Pervilä's doctoral thesis Data Center Energy Retrofits discusses the features of modern data centers through both case studies and global figures.
The individual case studies focus on the flagship facilities of major corporations, which are equipped to convince users of the companies' commitment to ecological responsibility. The global figures provide an overview of the common sizes of server rooms, and indicate that most server facilities are quite small and probably have poorer energy efficiency than the massive flagship data centers. According to Pervilä, major data centers such as those of Microsoft in Dublin and Quincy, Google in Saint-Ghislain and Hamina, Finland, Yahoo in Lockport, HP in Wynyard and Facebook in Prineville, are much alike, as they seek to minimise extraneous energy consumption by using adjacent natural cooling sources, such as bodies of water.
With these considerations in mind, the dissertation suggests a number of retrofit techniques for cooling data centers. These techniques range from the efficient delivery of ventilation air using free air cooling to exploiting exhaust heat in the experimental greenhouse on the Kumpula Science Campus in Helsinki, Finland.
The dissertation includes calculations for the minimum energy savings achievable with these techniques. For example, the amount of emissions reduced just by adopting free air cooling would be equivalent to 9.4 megatonnes of carbon dioxide based on the global electricity calculations from 2005. Global electricity consumption has increased since then, so the actual reduction would be correspondingly greater than in these calculations.
M.Sc Mikko Pervilä defends his doctoral dissertation in computer science at the University of Helsinki on 12 December 2013 on the Kumpula Science Campus. His opponent will be Professor Jon Crowcroft and the custos will be Professor Jussi Kangasharju.
The dissertation is available online: http://www.cs.helsinki.fi/u/pervila/phd/
Photos:
The greenhouse on a wintry rooftop in Kumpula, Helsinki, photographed by Mikko Pervilä. https://picasaweb.google.com/114818302608767208085/GreenhouseProject2012?noredirect=1#5704913640530562418
The greenhouse on a rooftop in Kumpula, Helsinki, photographed by Mikko Pervilä. https://picasaweb.google.com/114818302608767208085/GreenhouseProject2012?noredirect=1#5810259183254063490
See Pekka Tonteri's YouTube video on Pervilä's computers on the roof of the Exactum building in winter: Snow is not a problem for servers in Finland
More details on the dissertation and its public defence are also available on Facebook: https://www.facebook.com/events/1420054451546073/
Contact details:
Mikko Pervilä, University of Helsinki, Department of Computer Science +358 50 4480141, mikko.pervila@helsinki.fi
My best,
Minna Meriläinen-Tenhu, Press Officer, minna.merilainen@helsinki.fi