A method used is optimization of power dispatch using methods such as semi-definite programming. One software used is called SeDuMi. You can search for papers in this respect online for various works.

Here are several methodologies from various sources that may be of interest:

Methodology 1: Using UVC-C light to maintain data center's cooling efficiency

http://www.ecnmag.com/article/2016/01/ultraviolet-energy-important-addition-data-center-cooling-equation?et_cid=5080919&et_rid=345260701&type=cta&et_cid=5080919&et_rid=345260701&linkid=http%3a%2f%2fwww.ecnmag.com%2farticle%2f2016%2f01%2fultraviolet-energy-important-addition-data-center-cooling-equation%3fet_cid%3d5080919%26et_rid%3d%%subscriberid%%%26type%3dcta

Methodology 2:Using data center's individual server CPU's waste heat to assist in cooling a data center, and reduce Carbon Dioxide emissions:

http://www.fujitsu.com/global/about/resources/news/press-releases/2011/1107-02.html

Methodology 3: Using data centers' waste heat, to heat buildings and in once case, provide for a town's hot water needs in Finland:

http://ercim-news.ercim.eu/en79/special/using-waste-heat-from-data-centres-to-minimize-carbon-dioxide-emission

https://nextcity.org/daily/entry/seattle-turns-to-techs-wasted-heat-as-a-neighborhood-power-source

http://www.triplepundit.com/2016/02/233291/

http://greenbuildingelements.com/2014/09/29/amazon-heats-building-data-center-waste-heat/

http://www.solaripedia.com/files/1178.pdf

Methodology 4: Using a High Performance Computing center's waste heat to heat up part of an US Department of Energy's National Renewable Energy Laboratory campus by using liquid water cooling for a supercomputer, and consequently eliminating the need for compressor based cooling systems:

http://www.nrel.gov/news/features/feature_detail.cfm/feature_id=2133

Methodology 5: Using dairy farm waste to harness methane for energy production for data centers:

http://hpl.hp.com/news/2010/apr-jun/wastefordatacenter.html

Methodology 5: Waste heat reclamation from a gas energy supplier, to power eBay's data center:

http://www.datacenterdynamics.com/news/ebays-gas-powered-data-center-to-reclaim-waste-heat-energy/82414.fullarticle

Methodology 6: University of Alaska Fairbanks' study on Energy Efficiency for their campus supercomputer and server cooling requirements:

http://www.districtenergy.org/assets/pdfs/2010CampConf/Presentations/Wednesday/2B2RuckhausDataCenterEfficiency.pdf

There is also lots of work on trying to make distributing computing platforms (like Hadoop) more energy efficient by, for example, putting some nodes to sleep.  Try searching Google Scholar for "energy efficient Hadoop".

https://scholar.google.co.uk/scholar?q=hadoop+energy+efficient&hl=en&as_sdt=0,5