Product Design for the Environment: A Life Cycle Approach - Chapter 9 doc

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Chapter 9
Life Cycle Environmental Strategies and
Considerations for Product Design
To implement a process of integrated design that takes into consideration all
the phases of the life cycle, from the defi nition of product specifi cations to
its disposal, harmonizing a wide range of factors and including environ-
mental aspects, it is necessary to use opportune strategies allowing environ-
outlined a general view of how an intervention oriented toward environ-
mental protection can be integrated in the design and development process
through suitable design strategies for the environmental performance of a
product’s life cycle.
In this chapter, these same environmental strategies are considered in
greater detail, highlighting any aspects of particular interest to the designer
and describing the tools and techniques aiding their application. For each of
the strategies, particular emphasis will be placed on the defi nition of the
determinant factors conditioning their applicability and effectiveness, and
on the connection between these strategies and certain product properties
(reliability, durability)—the traditional subjects of engineering design.
9.1 Strategies for Improving Resources Exploitation and
Determinant Factors
A general overview of what may be considered the most effective environ-
mental strategies in the life cycle approach was presented in Chapter 8.
Underscoring the need to assimilate such strategies in the product design
and development process, it is opportune to focus on those which can be
directly linked to design choices, and thus become true and proper design
strategies (Section 8.2.1).
As highlighted before, the material dimension of the product–entity is
directly connected to choices made in the specifi cally designed-related phases
of the development process—conceptual, embodiment, and detail design.
The important parameters of such choices are referable to precisely this

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mental requirements to be incorporated in design practice. Chapter 8
218 Product Design for the Environment
physical dimension of the product (system architecture, materials, component
shapes and dimensions, interconnections, and junctions) and it was suggested
how an improvement in the environmental performance of its life cycle could
be achieved. Figure 9.1 highlights two main strategy typologies that, as well
as expedients for reducing the resources used in product manufacture, could
achieve this improvement:
• Useful Life Extension Strategies—Maintenance, repair, upgrading,
and adaptation of the product
• End-of-Life Strategies—Reuse and remanufacturing of systems and
components, recycling of materials in the primary production cycle
or in external cycles
Both of these types of intervention strategies have great potential in relation
to the environmental optimization of resource fl ows throughout the prod-
uct’s life cycle. Extending the useful life allows greater exploitation of the
resources used in production, avoiding the consumption of additional
resources in the manufacture of replacement products. Intervening to recover
the product, or parts of it, at the end-of-life allows its constituent components
or materials to be reused in the production of new products, thus reducing
FIGURE 9.1 Environmental strategies for improving exploitation of resources.
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Life Cycle Environmental Strategies and Considerations 219
the consumption of virgin material resources, conserving all or part of the
energy resources used, and reducing the volumes of waste. In the fi nal analy-
sis, these strategies favor an increase in the intensity with which the resources
employed in manufacturing the product are used, thereby improving their

exploitation. This aspect constitutes a substantial difference with respect to
those strategies directed at reducing the resources used in production
An effective integration between these two types of strategies for improving
exploitation of resources is both desirable and necessary, given that the
actions of interventions for extending the useful life can strongly condition
the opportunities for recovery, since these depend on the level of use to which
a product, its components, and constituent materials have been subjected
during the phases preceding recovery. Products that have been used for long
periods of time usually show a signifi cant deterioration in their functional
performance, and consequently allow a lower level of recovery than products
that are little used. The latter often still exhibit highly effi cient performance
and are, therefore, suitable for reuse.
9.1.1 Infl uence of External Factors and Product Durability
Applying strategies for the extension of the useful life and recovery at
end-of-life is, in general, conditioned by a wide range of factors determin-
ing its effectiveness (Rose et al., 1998; van Nes et al., 1999). The evaluation
of these factors is, therefore, essential for a correct implementation of these
strategies in product development. In this respect, external factors condi-
tioning the life expectation of a product are of particular importance
(Woodward, 1997):
• Functional Life—The period of time for which need for the product
is predicted to last
• Technological Life—The period of time that ends when the product
is so technologically obsolete that it must be replaced by another
based on superior technology
• Economic Life—The period of time that ends when the product’s
economic obsolescence is such it must be replaced by another char-
acterized by analogous performance but costing less
• Social and Legal Life—The period of time that ends when changes in
the desires of the consumer or in normative standards require the

product to be replaced
All these factors, which can be considered external to the context of design
choices linked to the product’s physical dimension, must be considered along
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(Chapter 8, Section 8.2).
220 Product Design for the Environment
with a fi nal, internal factor, which can be identifi ed as the “physical life.”
This is the period of time for which the product is expected to physically last,
maintaining its functional performance. This is, therefore, the factor directly
linking the main design choices (architecture, materials, shapes, and geome-
tries) with the predicted lifespan of the product.
In the design phase, the possibility of providing for the extension of the
product’s useful life and the reuse of parts depends precisely on the length of
a product’s physical life, which in turn is strictly bound to the durability of
its components (Giudice et al., 2003), understood in general terms as the
capacity to maintain the functional performance required of them. However,
this property should not be maximized indiscriminately since, for example,
in product sectors with a high level of technological innovation (and there-
fore with rapid obsolescence), excessive duration has a negative environ-
mental value, guaranteeing a useless extension of product and component
life that uses more resources in the production phase.
9.1.2 Identifi cation of Optimal Strategies
The defi nition of both strategies for improving resource exploitation must,
therefore, be subordinate to an evaluation of the external factors noted above,
linked to the market reality and to regulatory standards, company policies,
technological innovation, and aesthetic–cultural conditioning—all factors
that vary widely according to the product typology. Having quantifi ed the
main external factors, it is possible to identify the strategies most appropriate
to the product for varying its durability and that of its components.

A series of signifi cant evaluations can be made by comparing the physi-
cal life with the “replacement life,” defi ned as the period of time for which the
product is effectively usable. This is comparable to the period of time the prod-
uct is present on the market up to its defi nitive replacement, thus incorporat-
ing all the external conditioning considered above. Physical life represents the
predicted duration of a product’s full effi ciency (its potential lifespan), while
replacement life represents its effective lifespan, conditioned by factors such
as technological and economic obsolescence and other external factors.
On the basis of this comparison, a distinction can be made between two
types of useful life extension strategies:
• Maintenance, repair, and (more generally) service operations
constitute strategies intervening on the physical life (Physical life
extension strategies).
• Upgrading and adaptation of the product constitute strategies
intervening on the replacement life (Replacement life extension
strategies).
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Life Cycle Environmental Strategies and Considerations 221
Figure 9.2 shows how, depending on the product typology, it is possible to
identify the favorable conditions for extending the useful life by using the
two different types of strategies. For physical life extension strategies, these
conditions correspond to a long replacement life (indicating that the product
may be used for a long time), and a short physical life (revealing the brief
duration of some components, and therefore the limited capacity of the entire
system to guarantee the required performance). Conversely, for replacement
life extension strategies, these conditions correspond to a short replacement
life and a long physical life. These conditions not only indicate the inappro-
priateness of planning maintenance and service interventions (pointlessly
prolonging the product’s life), but also reveal a poor design, unsuited to

the predicted short span of effective use. Examples of the latter are over-
dimensioning or using unnecessarily high-performance materials. This
highly ineffective situation can be remedied through the upgrading or
adaptation of the product.
The other areas of the graph indicate conditions of equilibrium between
the two factors, representing the result of good design wherein the design
choices were such that the physical duration of the system was calibrated on
its expected effective useful life. This particular condition is generally referred
to as a condition of environmental effi ciency, where the resources used in
manufacturing the product are gauged on the basis of the effective exigencies,
avoiding over-dimensioning and consequent pointless wastage.
FIGURE 9.2 Identifi cation of optimal strategies: Extension of product useful
life.
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222 Product Design for the Environment
In an analogous way, Figure 9.3 shows the conditions favoring different
recovery strategies, from low-level recovery (recycling of materials) to a
higher level (reuse of the entire product) where:
• Area 1 represents the condition where the product, whose effective
useful life and presence on the market is expected to be short, is
composed of rapidly deteriorating components. This represents a
condition of gauged duration and is therefore, in principle, eco-
effi cient. At the end-of-life, any integral components are potentially
reusable in other products, but the most probable recovery strategy
is that of recycling the materials where possible.
• Area 2 represents the condition where the product, whose effective
useful life and presence on the market is again expected to be short,
is composed of long-lasting and functionally effi cient components.
At the end-of-life, the product may still be fully effi cient but, as a

result of external factors, cannot easily be reused because it is obso-
lete. Many of the components can potentially be reused as spare
parts or in other products. The most probable recovery strategy is
again the recycling of materials where possible.
• Area 3 represents the condition where the product, whose effective
useful life and market presence is expected to be long, is composed of
rapidly deteriorating components, so that its performance is not long-
lasting enough. At the end-of-life, components that are still effi cient
FIGURE 9.3 Identifi cation of optimal strategies: Recovery at product end-of-
life.
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Life Cycle Environmental Strategies and Considerations 223
can be reused in the manufacture of a product of the same type. For the
remaining components, only the recycling of materials is possible.
• Area 4 represents the condition where the product, whose effective
useful life and market presence is again expected to be long, is
composed of long-lasting and functionally effi cient components.
Like Area 1, this represents, in principle, an eco-effi cient condition of
gauged duration. If at the end-of-life the entire product is fully effi -
cient and if the length of the replacement life will allow it, in this case
it is possible to directly reuse the entire product. This would, in
theory, represent the most effi cient strategy for environmental protec-
tion unless the use of the product involved a signifi cant environmen-
tal impact that could be avoided by using a new, more effi cient
product in its stead. As an alternative to direct reuse, it is possible to
reuse some of the components. Finally, it is always possible to resort
to recycling the materials if feasible.
9.1.3 Use Process Modeling
The factors conditioning the strategies for improving exploitation of resources,

described above, are strictly dependent on how the product is used and on
the context in which this use takes place. To best defi ne the most effective
design strategies, it is therefore necessary to have a clear vision of the way in
which the product’s use process (understood as the phase of the life cycle
where the product performs its intended function) may develop. This
depends on how the product behavior (i.e., the way in which it executes its
function) interacts with the behavior of the user, and on how this interaction
is confi gured in the context of the environment where it takes place.
Ultimately, the use process is to be understood as an evolutionary process of
the product–user–environment system and must be anticipated at the design
stage. This requires a modeling of the use process, allowing the designer to
simulate the way this process develops so that it is possible to make well-
founded projections regarding the various factors that may condition the
design strategies, ensuring a sound and truly effective product development.
provide meaningful examples of how this problem can be approached—
limiting it to particular aspects and then using models to simulate the func-
tional behavior of products and variations in the level of quality (Hata et al.,
2000) or user behavior (Sakai et al., 2003).
The complex dynamics of the product–user–environment system deter-
mine the various factors, internal and external to the product, infl uencing
both its replacement life and its physical life. Therefore, these dynamics
should be analyzed for a meaningful estimation of the two important param-
eters. However, while the estimation of the physical life can be based on
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Studies of life cycle simulations, already discussed in Chapter 3, Section 3.2.4,
224 Product Design for the Environment
well-established modeling methods (such as fi nite element modeling that is
able to forecast the behavior of a product’s performance in relation to the
conditions of use with reliability), the estimation of the environmental condi-

tions and the interaction with the user, manifested in the various factors
conditioning the replacement life (functional, technological, economic, social)
is still a subject of research today (van der Vegte and Horvath, 2002).
9.2 Strategies for Extension of Useful Life and Design
Considerations
During their use, products can be subjected to servicing operations such as
maintenance and repair of worn or damaged components. The opportune-
ness of these operations can be assessed after an accurate estimation of the
environmental implications; if the maintenance and/or repair results in a
signifi cant environmental impact, it may be more appropriate to retire the
product unless its substitution requires the manufacture of a product with an
even greater environmental cost.
The requisites of durability (the capacity to maintain initial performance
levels over time) and maintainability (suitability for maintenance interven-
tions aimed at restoring performance levels to their initial values) are of
particular importance in the context of design. In reality, from a complete
perspective of environmental effi ciency these requisites must not be maxi-
mized indiscriminately. As noted in the case of durability, strengthening
these properties is positive only up to a certain point, beyond which they
begin to generate an impact greater than that caused by the replacement of
the product (due, for example, to a higher consumption of resources in the
use phase than that of a new, more effi cient product).
Maintenance (i.e., the set of activities regarding periodic prevention and
minor replacement interventions) is extremely important in limiting the
environmental and economic costs of repair, as well as the impacts of dump-
ing in waste disposal sites and of manufacturing a replacement product. To
facilitate maintenance it is necessary to perform cleaning operations during
use, ensure the accessibility of parts, arrange for the use of adequate equip-
ment, and provide for systems to monitor the condition of parts and compo-
nents. Other aspects that can extend the useful life of products are

upgradability (in relation to various phenomena of technological evolution
and modifi cation) and adaptability (for products rapidly becoming obsolete
and composed of more reconfi gurable components).
The strategies aimed at extending a product’s useful life were noted in
• Maintenance—Cleaning components; monitoring and diagnosis;
substitution of parts subject to wear
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Chapter 8, Section 8.2.2, and can be summarized as:
Life Cycle Environmental Strategies and Considerations 225
• Repair—Regeneration or replacement of damaged and worn parts
• Upgrading and adaptation—Substitution of obsolete parts; recon-
fi guration of components, adapting them to user requirements or
changes in the operating environment
It is appropriate to specify that in this book “adaptation” is meant as “recon-
fi guration” (i.e., an operation to change behaviors or states of the product
resulting in a new function) (Tomiyama, 1999). This meaning differs from
other more general defi nitions used in the literature, where “adaptation” is
described as a process aiming at transferring products or components in
additional usage phases, including maintenance, repair, remanufacturing,
upgrading, or rearrangement (Seliger et al., 1998).
With regard to the factors that render a product predisposed to the applica-
tion of one or more of these useful life extension strategies, it is appropriate
to make the following distinction:
• The determinant factors making product upgradability and
adaptability appropriate can only be analyzed on the basis of purely
qualitative assessments.
• The determinant factors making the provision and planning of
maintenance and repair interventions appropriate or necessary are
quantifi able on the basis of well-established engineering techniques,

as is the level of product maintainability and reparability.
This distinction, which is clearly a direct consequence of the different effects
these strategies have on the replacement life and physical life (Section 9.1.2),
has direct implications for the design tools and techniques, which are
adequately developed only in relation to the strategies of servicing and main-
tenance (i.e., those that can intervene on the product’s physical life). In fact,
strategies, the most appropriate DFX components are those aimed at main-
taining performance during the phase of use—Design for Serviceability
(DFS) (Makino et al., 1989; Gershenson and Ishii, 1993; Subramani and
Dewhurst, 1993) and Design for Maintainability (Klement, 1993; Kusiak
and Lee, 1997). These approaches to the problem of extending the prod-
uct’s useful life are closely interconnected and substantially complemen-
tary. It is necessary, however, to defi ne the relationships between them
more fully.
The term “service” includes interventions of diagnosis, maintenance,
repair, and whatever else may be necessary to guarantee that the system
functions correctly (Gershenson and Ishii, 1993). Design for Serviceability
therefore includes, in general terms, Design for Maintainability. In this
context, Design for Reliability (Rao, 1992; Birolini, 1993; Wallace and
Stephenson, 1996) also plays a leading role. The reliability of the system is
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as was noted in Chapter 8 (particularly in Section 8.3.2) with regard to these
226 Product Design for the Environment
generally defi ned as the measure of its capacity to maintain functionality
over a certain period of time, and is expressed by the probability that the
system will maintain this functionality (Blanchard et al., 1995). It can also be
quantifi ed by the percentage of the time during which the system operates
correctly, or by the frequency of malfunctions (Gershenson and Ishii, 1993).
Reliability is thus a product requisite that determines the necessity for

interventions of maintenance or repair, predicted and favored by DFS.
Ultimately, the latter is the design approach that best combines the most
appropriate characteristics for achieving strategies for extending the prod-
uct’s physical life. It must be conducted in strict correlation with the design
of the system’s reliability, as confi rmed by studies on the development and
use of design rules formulated to take into account both reliability and main-
tainability (Kusiak and Lee, 1997).
9.2.1 Design for Serviceability
Using the term “service” for the set of diagnosis, maintenance, and repair
interventions, together with any other intervention aimed at maintaining the
functionality of a system, the term “serviceability” is understood as the facil-
ity with which a system can be subjected to these interventions, expressed by
evaluation of:
• How easy it is to perform these interventions
• How much time they require and how much they cost
Design for Serviceability thus has the objective of aiding the designer in
making choices promoting the development of products prearranged for
service interventions (diagnosis, maintenance, repair) (Makino et al., 1989).
9.2.1.1 Main Aspects of Serviceability
On the basis of the defi nition of service given above, the main aspects of
serviceability can be summarized as follows (Gershenson and Ishii, 1993;
Klement, 1993):
• Diagnosability—A property of the constructional system making it
possible to identify the causes of malfunction and defi ne the conse-
quent service interventions necessary. Arranging the components in
groups according to function can favor diagnosability.
• Maintainability—A property of the constructional system making it
possible to operate planned or required maintenance interventions.
It renders the components requiring maintenance accessible to the
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Life Cycle Environmental Strategies and Considerations 227
operator and, by simplifying the maintenance procedures, favors
product maintainability.
• Reparability—A property of the constructional system allowing the
removal and substitution of parts or components, beyond the
replacement interventions foreseen by ordinary maintenance. It
can be favored by a correct modularization of the constructional
system’s architecture, which minimizes the costs of disassembly
and replacement.
9.2.1.2 Parameters of Constructional System Reliability
The reliability of a system is generally defi ned as the measure (in probabilistic
terms) of its capacity to maintain its functionality over a certain period of
time. An ideal constructional system of unlimited duration would have an
unvarying reliability of 1 (i.e., maximum probability of maintaining the
performance level). Since, in reality, no constructional system is completely
failure-free, it can be appropriate to deal with its functionality in terms of
reliability, so that while being characterized by a functionality of limited
duration it nevertheless offers a high probability of successfully completing
the functional task within a preset time span. Reliability is, therefore, a
product requisite determining the necessity for the maintenance or repair
interventions foreseen and favored by Design for Serviceability.
For further details regarding reliability parameters (failure rate, reliability
of a component or system, reliable life, and reliability frequency), refer to the
9.2.2
In order to evaluate the effect design choices may have on the product in terms
of its suitability for service interventions, it is possible to use some indicators
aimed at quantifying the costs and times involved in such interventions. A cost-
based measure can aid the designer in decision making. Considering service
modes as the ways in which a system may be serviced, Service Mode Analysis

is the method of describing which service modes will impact a particular design
and in what manner (Bryan et al., 1992; Gershenson and Ishii, 1993).
According to the approach called Component-based Service Mode,
malfunctions are directly referable to single components or groups of compo-
nents, and the required service interventions consist of repairing the
components responsible for the failure. Having set the duration of function-
ality, it is possible to evaluate the cost of service over the life cycle in relation
to the reliability of the single components. The service cost of the life cycle
defi ned in this way provides a fi rst evaluation of this property, limited to
repair interventions on malfunctioning components.
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specialist literature (Bazovsky, 1961 and 2004; Rao, 1992; Ireson et al., 1995).
Quantitative Evaluation of Serviceability Properties
228 Product Design for the Environment
An alternative and more complete expression can be defi ned using a different
approach, called Phenomena-based Service Mode. This approach takes into
consideration all the types of service interventions (repair, preventive and
corrective maintenance, diagnostics), treating them as generic service phenom-
ena (service mode phenomena). In this case, it is possible to arrive at a function
of the life cycle service cost that evidences the dependence of serviceability
properties on the main constructional characteristics of the product and on the
reliability of the system, since this determines the number and typology of
intervention phenomena and the factor of the frequency of operations, expressed
by appropriate reliability parameters (failure rates, reliability frequencies).
Some of these functions allowing the assessment of the life cycle service
the costs of service, it is possible to refer to service effi ciency, and this can also
Maintainability is defi ned as the probability of repairing a damaged system
or component within a certain time interval (Rao, 1992). Maintenance
interventions can be grouped according to two typologies:

• Corrective maintenance—Consisting of a set of unplanned interven-
tions required to repair or substitute malfunctioning parts in order to
restore functionality that was unexpectedly interrupted
• Preventive maintenance—Consisting of a set of interventions of
inspection and possible repair or substitution aimed at preventing
malfunctions and the deterioration of performance
For indicators that in some way quantify the maintainability of the construc-
tional system (i.e., its property of allowing and favoring maintenance interven-
tions), certain specialist literature (Blanchard et al., 1995) proposes functions
able to express the mean duration of maintenance interventions and the mean
time between them. This is called Mean Time Between Maintenance (MTBM),
the mean value of the length of time between the beginning of two successive
maintenance interventions; it can be expressed by reliability parameters.
9.2.3 Specifi c Determinant Factors for Useful Life Extension Strategies
With reference to the strategies considered here (maintenance, repair, upgrad-
ing, and adaptation), it is worth noting which specifi c factors determine the
suitability of a product or component for each strategy (i.e., the factors condi-
tioning the opportuneness or necessity of following a particular strategy).
For example, a component that requires frequent cleaning, is particularly
liable to deterioration phenomena and is characterized by low reliability and
durability; it is predisposed to the application of maintenance. Thus, the need
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cost are introduced and used in Chapter 16. As an alternative to evaluating
be quantifi ed as a function of the frequency of interventions (Subramani and
Dewhurst, 1993).
Life Cycle Environmental Strategies and Considerations 229
for cleaning, the sensitivity to phenomena of physical deterioration, and the
reliability and durability properties can be considered specifi c determinant
factors for the maintenance strategy.

Table 9.1 (upper part) summarizes the primary specifi c factors for each
strategy:
• Maintenance—Necessity for cleaning; physical or mechanical deterio-
ration (wear, aging, corrosion); reliability and durability of components
and system.
TABLE 9.1 Environmental strategies for improving exploitation of resources and
determinant factors
ENVIRONMENTAL STRATEGIES SPECIFIC DETERMINANT FACTORS
Useful Life
Extension
Maintenance Necessity for cleaning
Physical or mechanical deterioration
Reliability and durability of components and system
Repair Physical or mechanical deterioration
Risk of damage
Reliability and durability of components and system
Upgrading and
Adaptation
Obsolescence (technological, cultural, functional)
Changes in the use mode and environment
End-of-Life
Recovery
Reuse Physical or mechanical deterioration
Risk of damage
Technological obsolescence (also other types)
Reliability and durability of components and system
Ease of disassembly
Remanufacturing Physical or mechanical deterioration
Technological obsolescence (also other types)
Reliability and durability of components and system

Ease of disassembly and cheapness of remanufacturing
processes
Recycling Physical or mechanical deterioration
Technological obsolescence (also other types)
Reliability and durability of components and system
Recyclability and value of materials
Ease of material separation and cheapness of recycling
processes
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230 Product Design for the Environment
• Repair—Physical or mechanical deterioration; risk of damage; reli-
ability and durability of components and system.
• Upgrading and adaptation—Technological, cultural (change in
aesthetic values and modes of use), and functional (change in exigen-
cies of user) obsolescence; changes in the use mode and environment.
9.2.4 Design Expedients
Some design expedients that facilitate maintenance, repair, upgrading, and
adaptation include:
• Maintenance—Facilitate the accessibility of parts to be cleaned;
prearrange and facilitate access to and substitution of the parts dete-
riorating most rapidly; group components according to their physi-
cal and mechanical properties, levels of reliability, and shared
functions; prearrange systems for the diagnosis of parts requiring
maintenance and provide for the application of diagnostic instru-
ments on critical components.
• Repair—Prearrange and favor the removal and reassembly of critical
components subject to deterioration and damage; design standard-
ized parts and components.
• Upgrading and adaptation—Design modular and reconfi gurable

architecture for adaptation to different environments; design multi-
functional products for adaptation to the evolutions of the user.
9.2.5 Design Variables
From an analysis of the specifi c factors determinant for the strategies and
of the design expedients directed at achieving the requisites for extending
the product’s useful life, it is possible to identify the main design variables
upon which interventions can be made in order to follow the strategies in
question:
• Choice of materials and geometric properties—Infl uences the physi-
cal and mechanical performance of components over time, and their
reliability and durability.
• Layout of product—Determines the reliability of the system, infl u-
ences the component accessibility, and can allow the grouping of
components according to their functionality or other performance
characteristics.
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Life Cycle Environmental Strategies and Considerations 231
• Modularity of the architecture—Infl uences the ease of access,
removal and substitution of critical components, and reconfi guration
of the system.
9.3 Strategies for Recovery at End-of-Life and Design
Considerations
At the end of a product’s useful life there are various opportunities for
exploiting the resources used in its production; the functionalities of the
entire product or some of its parts can be recovered and re-employed for the
same task or other tasks (after collection and transport), or its original func-
tionality can be restored and the product used as though new (after reprocess-
ing). Also, its material and energy content can be exploited through recycling,
composting, or incinerating its constituent materials. Some of these activities,

such as reusing the product or its components, can be considered as extend-
In this preliminary formalization, however, it is preferred to maintain the
distinction between strategies intervening during the phase of use (e.g., main-
tenance) and those intervening after this phase. Reuse can be understood as
one of the latter, to the point where some authors consider it a phase in itself,
following that of use (Roozenburg and Eekels, 1995).
From this perspective, it becomes important to conceive and design prod-
ucts that are easily disassembled in order to favor the rapid and economic
separation of parts or materials and the reuse of components, or to facilitate
the separation of materials for recycling (when they are heterogeneous and
mutually incompatible), for isolation (when they are toxic or dangerous), or
for composting or incineration.
Products destined for reuse, in their entirety or only in part, can be collected
and directed at the same original use or, alternatively, at another use demand-
ing lower performance standards and having less-stringent requisites. The
operations required may be limited to the cleaning or disassembly of some
parts and their reassembly in new products. With regard to the possibility of
remanufacturing (i.e., the process of reconditioning products worn through
use and returning them to their almost original condition), it is especially
important to facilitate the removal and substitution of parts and components
and favor their interchangeability within the same line of products.
When the objective of disassembly is recycling, the condition of equilibrium
defi ning the profi t margin and economic sustainability is sensible to variations
in the price of virgin materials and in the costs of collection and recycling. In
this case, therefore, economic effi ciency results from minimizing the time and
costs of the necessary processes and in both the preservation and the exploita-
tion of the materials recovered (the greater the purity of the materials, the
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ing of the product’s useful life; this will be further discussed in Chapter 15.

232 Product Design for the Environment
better they preserve their performance characteristics and the greater their
market value). As an alternative to disassembly, it is possible to consider a
fragmentation process, followed by the separation and cleaning of the pieces.
Apart from the economic aspect, not all materials are equally recyclable. It
is possible that the performance characteristics of the recycled material are
substantially different than those of the initial virgin material, or that a mate-
rial is easy to recycle at the technological level but requires a great expendi-
ture of energy in the application of the necessary processes, outweighing the
environmental advantages offered by the recycling itself.
As an alternative to recycling, another way of exploiting materials is that of
recovering their energy content through incineration or other suitable
processes. In either case, the environmental advantage is twofold: fi rst, the
impact due to the disposal of waste materials is avoided and, second,
non virgin resources are made available, thus avoiding the impacts due to the
production of a corresponding quantity of energy obtained from natural
resources. Therefore, the criteria for the choice of materials direct the designer
toward materials allowing their original performance characteristics to be
recovered easily (avoiding the use of composites and additives) or those
allowing the effi cient recovery of their energy content, with little impact on
the environment.
9.3.1 Defi nition of Recovery Strategies at End-of-Life
The strategies for the recovery of resources at the end of a product’s useful
life can be divided into various typologies (Overby, 1979; Ishii et al., 1994;
Navin-Chandra, 1994; Zang et al., 1997; Gungor e Gupta, 1999; Rose
strategies of direct reuse, reuse of parts, and the recycling of materials
(Section 8.2.3). This discussion showed how each of these corresponds to
a different potential environmental benefi t, in turn depending on the level at
which the recovery fl ow reenters the life cycle (this aspect is illustrated in
be closed (closed loop) or open (open loop), leading to recycling internal or

external to the primary life cycle.
A complete panorama of the entire range of possible recovery strategies can
be structured by clearly distinguishing between strategies for the recovery of
the entire product and those for its parts or components (Dowie, 1994). Starting
from this presupposition, at the end of a product’s useful life the recovery

• If the product is in optimum working condition and guarantees the
functional standards, it can be directly reused (in the fi gure, Reuse of
Product).
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et al., 2002). In Chapter 8, a preliminary distinction was drawn between
intervention can follow one of the following different routes (Figure 9.4):
Chapter 2, Figure 2.9). Another distinction that must be made is that between
the recycling fl ows which, as was anticipated in Chapter 2, Section 2.5.2, can
Life Cycle Environmental Strategies and Considerations 233
• If it is in good condition it can be reprocessed, reconditioned, and
reused (Remanufacturing of Product).
• If it is entirely composed of recyclable and compatible materials, it
can be fully recycled (Recycling of Product).
• If the product contains parts that can be reused, reprocessed, or recy-
cled, it must be disassembled. This operation can, in turn, lead to
four different possibilities of recovery: reusable parts can be detached
from the product, returned to the production process, tested and
reassembled in new products (Reuse of Components); other parts
can be reprocessed before being reassembled in new products
(Remanufacturing of Components); parts unsuitable for the two
previous solutions and composed of recyclable materials can be
directly routed to material recycling (Recycling of Components);
parts containing volumes of recyclable materials can be dismantled

and the resulting materials separated into volumes for recycling and
volumes for dumping (Dismantling, Shredding, and Recycling of
Components).
• If the product contains small volumes of recyclable materials, it can
be dismantled to allow the subsequent selection and recycling of
these materials (Dismantling, Shredding, and Recycling of Product).
• Finally, if the product does not contain reusable or recyclable parts it
is directly routed to the waste disposal site (Disposal).
In this clearly hierarchical demarcation of the possible options at the prod-
uct’s end-of-life, some ambiguity may be found in the interpretation of the
term “remanufacturing.” It is appropriate, therefore, to specify that in this
FIGURE 9.4 End-of-life strategies: Recovery options.
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234 Product Design for the Environment
book “remanufacturing” of either product or component means an
intervention of reuse that requires intermediate processes of regeneration
and reconditioning, without resorting to substitutions or substantial repairs.
This meaning is embedded in the more general defi nitions, where “remanu-
facturing” is understood as a process of reuse where the original forms of the
product and components are preserved (Bras and McIntosh, 1999). At the
same time it differs from other, more detailed defi nitions frequently used in
the literature, where “remanufacturing” is defi ned as the process by which a
product at end-of-life is completely disassembled in order to recover compo-
nents that are still usable. After cleaning and inspection, these components
are reassembled with others, both used and new, in order to recreate the
product with its original performance (Lund, 1984).
This defi nition corresponds, instead, to the option indicated as “reuse of
components” in the scheme reported above. In all cases, it was considered
preferable to exclude the possibility that some product components are

replaced or repaired, an intervention typology that is included within the
useful life extension strategies, although other authors consider it assimilable
to remanufacturing (Pnueli and Zussman, 1997). For the same reason, inter-
ventions of upgrading are also excluded in this book, despite the fact that
some authors consider it part of remanufacturing (Thierry et al., 1995).
9.3.2 Management and Optimization of Recovery Strategies
The goal of applying the possible recovery strategies described above is to
realize an ideal condition of a closed loop resource fl ow, where materials,
components, and products circulate in a qualitatively and economically effi -
cient way (Giudice et al., 2001; Umeda, 2001). With this perspective, the envi-
ronmental strategies of recovery achieve this good cycling of resources and
product design puts these strategies into action. Life Cycle Management
and effi cient fl ow of resources. With particular reference to the management
of recovery strategies, Product Recovery Management (PRM) is understood
as the management of the entire ensemble of products, components, and
materials (used or discarded) that are the responsibility of a manufacturing
company (Thierry et al., 1995).
The overview of the possible recovery strategies presented above follows
a hierarchical order, according to a decreasing potential for environmental
benefi t. However, this criterion of hierarchical distinction between recovery
levels allows the defi nition of the most effective strategy only in relation to
the environmental aspect of the recovery question. In this case, the optimal
solution is one that harmonizes environmental requirements with the times
and costs of the processes under consideration. On the other hand, even
when considering only the environmental aspect of the problem, the overall
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(Chapter 3) must then perform the important role of maintaining this active
Life Cycle Environmental Strategies and Considerations 235
plan for recovery at end-of-life must be such that it maximizes the recovery

of resources while simultaneously minimizing the use of resources and the
production of emission phenomena by the recovery processes themselves.
This confi rms the validity of the systemic approach, adopted from the very
beginning of this book, according to which the correct analysis of the envi-
ronmental issues associated with the life cycle of a product requires an eval-
uation of all the fl ows of resources and emissions involved in each phase of
the cycle.
According to this comprehensive perspective of the question, the problem
of recovery can then be formulated as: Given a product (or a design proposal),
determine the recovery plan able to effectively balance the costs of the recov-
ery processes and the corresponding profi ts, understood in terms of resources
used and recovered (Navin-Chandra, 1994).
Figure 9.5 represents the problem defi ned in this way, making it possible
to identify the most favorable conditions. The trends of the curves are typical
of the functions they express. The costs of recovery (disassembly, testing,
remanufacturing) become prohibitive with the increasing depth of the recov-
ery process. On the other hand, the revenues, beginning from a certain depth
of recovery, tend to stabilize. As a consequence, the profi t curve (given by the
difference between the curves of revenue and cost) has a trend of the type
shown in the fi gure.
FIGURE 9.5 Recovery curves and optimization of recovery
planning. (Adapted from Navin-Chandra, D., The recovery problem
in product design, Journal of Engineering Design, 5(1), 67–87,
1994, Fig. 3-1.)
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236 Product Design for the Environment
The optimization of recovery, therefore, consists of designing the product
and its recovery plan in order to:
• Shift the peak of the profi t curve toward a greater depth of the recovery

intervention
• Increase the value of the profi t at the peak
9.3.3 Approaches and Tools for Design
e oriented
toward the planning of processes at the end-of-life. They belong to the general
area of Design for Product Retirement/Recovery (Ishii et al., 1994; Navin-
Chandra, 1994; Kriwet et al., 1995; Zhang et al., 1997; Gungor and Gupta,
1999). Using more specifi c terminology, reference is frequently made to
Design for Remanufacturing (Shu and Flowers, 1993; Bras and McIntosh,
1999) and Design for Recycling (Burke et al., 1992; Beitz, 1993).
Another DFX technique, known as Design for Disassembly, is oriented
toward design and planning for the disassembly of systems (Boothroyd and
Alting, 1992; Jovane et al., 1993; Scheuring et al., 1994; Harjula et al., 1996).
As noted previously, although Design for Disassembly is frequently directed
at recovery interventions at the end-of-life, in reality it is a tool that cuts across
the two environmental strategies (extension of useful life and recovery
at end-of-life) since it is targeted at a product characteristic—the ease of
disassembly—that facilitates both strategies. Some important considerations
regarding Design for Disassembly and Design for Recycling that represent
(at the current state of the art) the most well-established design approaches,
are discussed below.
9.3.3.1 Design for Disassembly
The disassembly of a used product is necessary whenever it is advantageous
to proceed with the recovery of a product’s subunits or single components.
Disassembly can be defi ned as a systematic removal of the desired parts from
an assembly, with the condition that the disassembly process does not result
in any damage to the parts (Brennan et al., 1994). Therefore, it differs from
“dismantling” due to its reversible and nondestructive character.
Disassembly is essential in the context of recovery strategies and also has
great importance for useful life extension strategies because it can favor the

properties of product serviceability discussed in Section 9.2.1. The objectives
of disassembly are, therefore, to facilitate (Lambert, 1997):
• Recovery of parts, components, and subassemblies reusable in new
products
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As was noted in Chapter 8, Section 8.3.2, various DFX tools ar
Life Cycle Environmental Strategies and Considerations 237
• Recovery of recyclable materials
• Removal of dangerous or toxic components and materials
• Accessibility to parts or components that may be subjected to service
operations
These objectives may also be extended to removal and replacement of
components to be upgraded, and separation of parts and components to be
reconfi gured.
Design for Disassembly (DFD) can thus be defi ned as a design approach
whose objective is that of optimizing product architecture and the other
design parameters in relation to the following requisites:
• Simple and rapid separability of parts to be serviced, replaced, or
recovered
• Possibility of separating fractions of a component composed of recy-
clable materials without compromising their potential for recycling
• Limitation of disassembly costs
Understood as a design tool, DFD can, therefore, target the harmonization
between product layout, component geometries, and materials and junction
systems in relation to the disassemblability of the system.
With this objective, the product design intervention can be interpreted on
different levels (Yamagiwa et al., 1999): Frame Design (study of product
layout); Part Design (study of the geometry and materials of parts); and Joint
Design (study of the junction systems). Some design guidelines for an inter-

vention directed at facilitating the disassembly of the constructional system
These can be summarized on the basis of certain constructional standards
(GE Plastics, 1992; ICER, 1993; VDI 2243, 2002) and contributions found in
the literature (Beitz, 1993; Jovane et al., 1993; Chen et al., 1994; Dowie and
Simon, 1994).
constructional system and the optimal planning of disassembly processes are
examined.
9.3.3.2 Design for Recycling
In general, recycling can be defi ned as the set of processes for the recovery of
materials or components from a used product in order to render them usable
in new products (Jovane et al., 1993; Kriwet et al., 1995). Design for Recycling
thus consists of the design intervention intended to provide for and to facili-
tate the operations of recovery and recycling at the end of a product’s life.
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can be associated with each level of design action, as shown in Table 9.2.
For more details regarding the disassembly of products, refer to Chapters
13 and 14, where the issues of the disassembly depth of the components of a
238 Product Design for the Environment
The problems involved are numerous, and some are closely linked to those
typical of disassembly regarding the separation of materials and components
(Table 9.2). The essential requirements for a design oriented toward recycling
(provided that they are limited to those strictly tied to the properties of the
materials, the subject of recycling interventions) are briefl y summarized
below:
• Distribution of the materials in the product architecture in relation to
their intrinsic properties of recyclability, their compatibility in terms of
the recycling processes, and to the heterogeneity of the components or
main subunits
TABLE 9.2 Design for Disassembly: Guidelines, expedients, and requisites

DESIGN LEVELS GUIDELINES
Frame Design
(Product Architecture
and Layout)
Separability of toxic or harmful parts and materials
Separability of high-value parts and materials
Subdivision into easily separable subunits
Modularity of architecture
Simplifi cation of the hierarchy of connections between parts
Prearrangement of accessible and recognizable pathways for disas-
sembly operations
Part Design
(Geometries and
Materials)
Less variety and incompatibility of materials
Fewer parts and components which are asymmetrical or diffi cult to
handle
Presence of fl at surfaces and standardized handholds
Arrangement of handholds near the center of gravity
Provision of lines or areas of preferential breakage (elimination of
incompatible inserts)
Provision of cutting or fracture paths along the interfaces of incom-
patible materials
Highlighting breakage points to facilitate identifying and reaching
them
Joint Design
(Junction Systems)
Use reversible junction systems
Use of junction elements that can be destroyed physically or
chemically

Less variety of fasteners and fewer types of fasteners that are dif-
fi cult to remove
Fewer fastening systems that to be opened require simultaneous
actions
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Life Cycle Environmental Strategies and Considerations 239
• Absence of environmentally dangerous materials (toxic for humans,
other organisms, or the environment in relation to the phases of
production, use, and recycling)
• Clearly identifi able parts and their constituent materials
Recycling can also be understood as a strategy for the extension of the useful
life of materials, given that it allows some kind of reuse of the materials
recovered. Extending the life of materials, therefore, means making them
function beyond the duration of the product they are part of. As noted earlier,
the resulting environmental advantage is twofold:
• Avoiding the environmental impact due to the disposal of waste
materials
• Making available nonvirgin resources for the production of materials
or energy, according to the type of recycling, with a consequent
reduction in the impact due to the production of corresponding
quantities of materials and energy obtained from virgin natural
resources
With regard to the typologies of recycling processes, these generally consist
of a series of activities directed at the regeneration of material and its subse-
quent transformation. These activities include collection, separation, and
cleaning, together with the processing of materials recovered from the waste
fl ow and reintroduced into the original or external lifecycle. These typologies
are grouped on the basis of the type of processing used on the materials
(chemical recycling, mechanical recycling). Given that chemical recycling is

not, at present, very practical because of its complexity and cost, the physical–
mechanical recycling typology is the most commonly used on both homog-
enous and heterogeneous materials.
A design intervention with the objective of defi ning a recyclable product
must evaluate two possible alternatives:
• The use of materials homogenous from a physical-chemical point of
view, which can be directly recycled, eliminating even the operations
of disassembly (this alternative is suited to the case where the prod-
uct is characterized by limited functional complexity and, there-
fore, does not require the use of materials with widely differing
performances)
• The use of materials that are mutually incompatible but easily sepa-
rable (this alternative is suited to products characterized by a func-
tional complexity requiring materials with different performances)
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240 Product Design for the Environment
In economic terms, the recycling strategy is characterized by costs and revenues
dependent on factors of various kinds:
• Recycling costs—The costs of the various phases of the recycling
processes (cost of the operations of collection and transport, disas-
sembly and separation, cleaning and reprocessing). They largely
depend on the materials themselves, on the product architecture,
and on the other constructional characteristics.
• Recycling revenues—Depend on various kinds of economic factors,
such as the cost of virgin materials (if this increases, it raises the value
of the recycled materials) and the effi ciency of the product architec-
ture and of the recycling processes (easily disassembled materials
tend to be less contaminated, and the purity of the material infl uences
its characteristics and, therefore, its market value).

These simple considerations demonstrate the importance of a design inter-
vention that defi nes a product architecture and component geometry aimed
at the economically feasible recycling of materials.
9.3.4 Quantitative Evaluation of the Potential for Recovery
In order to evaluate the effect that design choices can have in terms of disas-
semblability and recyclability, certain indices can be used that quantify
various characteristics of the constructional system that are ascribable to
these properties (Navin-Chandra, 1991; Simon and Dowie, 1993; Takata
et al., 2003). The more important indices are based on certain primary
considerations. For the purposes of their defi nition, it is possible to represent
the disassembly process with two primary models (for a complete over-
The fi rst model, evidencing the depth of the disassembly levels (see also
sponding parts that become separated, and is represented in tree diagrams
second level corresponds to main subassemblies, and so on down to the
single components. A graphical representation of this kind is clearly helpful
for simplifying the architecture because, if the diagram is structured on
numerous levels, the product is characterized by great structural depth and,
consequently, by ineffi cient disassembly.
In the second model, the process of disassembly is represented by a diagram
of the order of precedence, commonly used for assembly planning. When
applied to the inverse process, it evidences the complexity of the disassembly
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Chapter 13), correlates the successive phases of disassembly with the corre-
(Figure 9.6). Its fi rst level corresponds to the product still assembled, the
process. Figure 9.7 shows an example of a diagram of precedence wherein
view of disassembly process modeling, see the literature) (Tang et al., 2000;
Lambert, 2003).
Life Cycle Environmental Strategies and Considerations 241
each node of the diagram represents an operation of disassembly; the

arrows indicate the direction of the process and thus the sequence of the
operations.
In effect, two possible relations are created:
• Relation of divergence—Represents the condition where the process
of disassembly offers a choice of several operations that can be
performed in parallel, reducing the time required to complete the
operation and, therefore, the cost.
FIGURE 9.6 Tree diagram for the analysis of disassem-
bly depth.
FIGURE 9.7 Precedence diagram for disassembly model-
ing.
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