Once Upon a Time, every plant had an air system, fed by central compressors that hissed cheerfully whether working or idling. Hey, air was free, right? Maybe then, but not today.  Energy consumption is one of the key factors determining how a machine or system is received these days. Different regions of the world have experienced differing energy costs over time. But today, users in every region want to squeeze the most bang from the fewest pneumatic bucks. 

http://www.designworldonline.com/articles/5265/203/Four-Ways-to-Boo...