American Council for an Energy-Efficient Economy (ACEEE), Research Report IE1402, March 2014, by Christopher Russell. (Free registration required to view full text.)
http://aceee.org/research-report/ie1402

"This report evaluates outsourcing as a tool for achieving the energy efficiency program goals.  While offered to industrial and other large facilities primarily to ensure the reliability of energy performance, energy service outsourcing can also enhance energy efficiency in these facilities. The report describes the business models and considerations for both providing and consuming outsourced energy services. Awareness of these issues is crucial to the success of any energy efficiency program that attempts to achieve its goals by relying on the market for energy service outsourcing."