Energy saving

What happens at the manufacturer is that the specification for equipment is written (by the end user, or some hired intermediary) around some operating point ... and most often, that point is the "full load" or "100 percent" rating of the machine. Therefore, the design effort goes into making that specified operating point the best possible in a variety of terms, including: optimizing material usage during manufacture, minimizing material and labor costs during manufacture, optimizing the spectrum of performance criteria (including efficiency at the specified operating point), maximizing overall equipment reliability, minimizing personnel hazards during manufacture and operation, and maximizing accessibility for maintenance purposes. Sometimes one choice benefits more than one result ... but far more often, there is a trade off between the benefits and some determination is made on what is most "important". And as we are all different human beings, so too does the heirarchy change from one consumer to the next.

The difficulty - as you've already noted - arises when the SPECIFIED performance requirement (i.e. full load) is not the same as the ACTUAL performance requirement.
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