Variable costs
are a part of the cost calculation with the engineering formula. They
consider those costs that only occur when the system is working. When it stands
by, these costs are zero.
But when the machine works, it consumes energy
in the form of fuel or electricity, plus other consumables like hydraulic oil,
lubricants, and so on.
It is not too
difficult to calculate these costs per hour. With fuel, we multiply consumption
(liters per hour) with the price per liter, for example.
For a general
approximation, one can also take the sum of fixed costs and multiply it with nay estimated factor. With expensive machines it is roughly 10%,
and it climbs up to 50% with simple machines like the chainsaw.
