KADENA AIR BASE, Japan -- Senior Airman Derek Hunter, 18th Civil Engineer Squadron Heating, Ventilation, Air Conditioning and Refrigeration technician, thumbs through the remote control to a heating ventilation and cooling system April 21. In the past, Kadena’s HVAC/R shop has had to replace large, outdoor, energy-wasting chiller units for buildings’ AC systems on military installations across the island nearly every three years. Now, Kadena recently instituted an initiative through the Air Force Smart Operations for the 21st Century program to replace the antiquated, over-oxidizing equipment with protected, indoor chillers to save the Air Force money. (U.S. Air Force photo/Staff Sgt. Jonathan Steffen)