Four categories of the cost information including material costs,
system cost (labor, depreciation etc.), energy cost and waste
treatment cost can be compiled as the quantity data based on
material flow. The MFCA results allocate product costs into 2 types:
“positive product cost” and “negative product cost”. “Positive
product costs” are the costs put into process products (positive
products) released to the next process. “Negative product costs” or
“loss costs” are costs put into wasted or recycled items (negative
products). Material loss cost can be simply calculated by multiplying
individual quantities (kg) of waste by their material purchased
unit price, or by using raw material cost multiplies by
percent of material loss by weight. Energy or system loss cost can
be calculated by using mass allocation method: cost of energy input
multiplied by percent of material loss by weight in each subprocess
(out of material input in each sub-process) (METI, 2007).
MFCA considers the main material flows in all processes as well
as sub materials, except auxiliary, materials. Main materials, sub
materials and auxiliary materials are defined as follows