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appropriate position inside or out of the system boundary requires establishing a
quantified relationship to cutoff criteria based on their potential to do harm at some
point in their life cycle.
5.3.6 What if the Process Used to Make One Thing
Simultaneously Produces Other Things?
Most designers are commissioned to design a single object or system. As challenging as it can be to establish the system’s boundary conditions and cutoff criteria in a
design, the next step is arguably even more so. Many industrial manufacturing processes produce more than a single useful product. The various inputs and outputs of
the entire process may need to be divided and separately assigned or allocated to the
different resulting products. For instance, making a wooden table involves subtractive processes, to shape its individual elements from larger pieces of dried lumber,
where the leftover wood has other potential uses. Depending on the specific processes used (sawing, coping, milling, drilling) and the wood feedstock used (hardwood, softwood, solid, laminated, fiberboard, etc.), useful wooden co-products
could include solid wooden toys or sawdust to be used as economically valuable
feedstock to make new pressed fiberboards, wood pellets, or for its direct use as fuel
in an onsite furnace.
Appropriately allocating percentages of environmental resources and waste
emissions among multiple-designed primary products and co-products can be a
controversial activity. There is disagreement around the general methods used to
make decisions around how specific percentages are split and assigned since the
results can vary across methods or some are not practical using present data and
software (Curran 2012). There are a few different approaches to allocate or to avoid
the need to allocate. For those analyzing primary agricultural or industrial products
(wheat, energy, steel, lumber, etc.), it is critical to establish a clear and defensible
allocation strategy since the co-products are the feedstock for entire subindustries
(straw, slag, cellulose, etc.) and can. For the designer focused on downstream systems, it is more important to grasp the broad implications of these various approaches
than be able to technically resolve the problems inherent in tracking and allocating
the environmental impacts along each flow path. Consideration of upstream natural
resource extraction and processing systems may, however, provide insight into
alternative design approaches.
ISO 14044 4.3.4 establishes a procedure to address allocation problems through
a series of steps (ISO 2006b). Step 1 avoids allocation by either dividing unit processes into multiple subprocesses for each co-product and collecting input and output data related to each discreet subprocess (1a) or expanding the product system to
include the additional utility/value the co-products provide (1b). 1a creates separate
LCAs for each co-product that can be taken together to find the total flow of inputs
from and outputs to the ecosphere. 1b produces a single LCA inside of which the
5.3 Goal and Scope Definition
appropriate position inside or out of the system boundary requires establishing a
quantified relationship to cutoff criteria based on their potential to do harm at some
point in their life cycle.
5.3.6 What if the Process Used to Make One Thing
Simultaneously Produces Other Things?
Most designers are commissioned to design a single object or system. As challenging as it can be to establish the system’s boundary conditions and cutoff criteria in a
design, the next step is arguably even more so. Many industrial manufacturing processes produce more than a single useful product. The various inputs and outputs of
the entire process may need to be divided and separately assigned or allocated to the
different resulting products. For instance, making a wooden table involves subtractive processes, to shape its individual elements from larger pieces of dried lumber,
where the leftover wood has other potential uses. Depending on the specific processes used (sawing, coping, milling, drilling) and the wood feedstock used (hardwood, softwood, solid, laminated, fiberboard, etc.), useful wooden co-products
could include solid wooden toys or sawdust to be used as economically valuable
feedstock to make new pressed fiberboards, wood pellets, or for its direct use as fuel
in an onsite furnace.
Appropriately allocating percentages of environmental resources and waste
emissions among multiple-designed primary products and co-products can be a
controversial activity. There is disagreement around the general methods used to
make decisions around how specific percentages are split and assigned since the
results can vary across methods or some are not practical using present data and
software (Curran 2012). There are a few different approaches to allocate or to avoid
the need to allocate. For those analyzing primary agricultural or industrial products
(wheat, energy, steel, lumber, etc.), it is critical to establish a clear and defensible
allocation strategy since the co-products are the feedstock for entire subindustries
(straw, slag, cellulose, etc.) and can. For the designer focused on downstream systems, it is more important to grasp the broad implications of these various approaches
than be able to technically resolve the problems inherent in tracking and allocating
the environmental impacts along each flow path. Consideration of upstream natural
resource extraction and processing systems may, however, provide insight into
alternative design approaches.
ISO 14044 4.3.4 establishes a procedure to address allocation problems through
a series of steps (ISO 2006b). Step 1 avoids allocation by either dividing unit processes into multiple subprocesses for each co-product and collecting input and output data related to each discreet subprocess (1a) or expanding the product system to
include the additional utility/value the co-products provide (1b). 1a creates separate
LCAs for each co-product that can be taken together to find the total flow of inputs
from and outputs to the ecosphere. 1b produces a single LCA inside of which the
5.3 Goal and Scope Definition