Brian Jarvis and Robert DeRuyter check instrumentation hooked up to a chiller Sept. 29, 2011, at an undisclosed location in Southwest Asia. Jarvis is trying to determine at what level of use the air conditioning units will run most efficiently. Jarvis is the U.S. Air Forces Central Command energy manager, and DeRuyter is an air conditioning service technician assigned to the 379th Expeditionary Civil Engineer Squadron. (U.S. Air Force photo/Master Sgt. Gary J. Rihn)