15

DESIGN FOR SUSTAINABILITY

AND THE ENVIRONMENT

The ecosystem of planet Earth is human-dominated. The standard of living of hu-

mans is due, in large part, to their ability to develop technology to control the eco-
system. Rather than adapting to the earth’s environment, humans have found ways
to alter their immediate environment to meet their own needs. So significant is the
human alteration of the planet that some scientists declared a new geological era: the
Anthropocene era, also known as the age of the human.1
Today’s designers and engineers are expected to move beyond design for recy-
clability (an end-of-life strategy), beyond design for the environment (a life-cycle
objective), to design for sustainability—an all encompassing paradigm that reaches
beyond an artifact’s life cycle into the social fabric of everyday life. Sustainable
development can be generally defined as social and economic growth that is compat-
ible with the environment.2
Global sustainability issues far exceed the boundaries of engineering design, yet
educators are required to impart the full scope of sustainability to students. The
ABET3 accreditation criteria for engineering programs expanded one criterion to
include sustainability awareness as follows:
An ability to understand ethical and professional responsibilities and the impact of
technical and/or scientific solutions in global, economic, environmental, and societal
contexts4

This chapter introduces the topic of sustainability, its ramifications for engineer-
ing, and guidance in designing to meet sustainability challenges.
15

1. B. R. Allenby, The Theory and Practice of Sustainable Engineering, Prentice Hall, Upper Saddle
River, NJ, 2011.
2. M. R. Chertow, “The IPAT Equation and Its Variants,” Journal of Industrial Ecology, Vol. 4,
pp. 13–29, 2000.
3. Accreditation Board for Engineering and Technology, Inc.
4. “Criteria for Accrediting Applied and Natural Science Programs, 2019–2020 | ABET,” Abet.org,
2019. Web. 13 June 2019.

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 15-2 e ng i n e e r i ng d e s i g n

15.1
THE ENVIRONMENTAL MOVEMENT

This section will provide the briefest of introductions to the language of the environ-
mental movement to contrast the scope of sustainability and follow some of its core
principles. Understanding relies on precise definitions of terms, particularly when
branching into new fields of study. An ecosystem is a closed geographical area, in-
cluding the living entities in the space above and below it. The area may have inputs
and outputs, but the systems cooperate to maintain a balanced environment. All eco-
systems on the earth combine into what is known as the biosphere. Earth’s biosphere
is the part of the planet that can support life and includes the earth’s crust, atmo-
sphere, and water layers.

15.1.1 Ecosystems and Balance

Ecosystems can be modeled in engineering terms as control volumes with defined

physical boundaries enclosing living organisms, natural elements (i.e., portion of the
earth’s surface and crust, air, water), people, and man-made structures. Ongoing eco-
systems must achieve a balance among all the exchanges of energy and material among
its inhabitants. Members of an ecosystem can be modeled as a set of function struc-
tures interacting with each other and their environment by exchanging flows of energy,
material, and signals (see Chapter 6). Ecosystem ecology is the study of these flows.
An ecosystem survives as long as the resources within it are adequate to support
the living systems it holds. The resources may be supplied from other members
inside the system, from the outside, or restored through some cyclic action of the
system itself. The earth supplies essential resources for plants and animals through
sunlight and three natural cycles: carbon, nitrogen, and water. Disruption of these
inputs causes imbalance in the ecosystems, which will ultimately impact the surviv-
ability of its inhabitants.
Basic biological ecosystems maintain balance by adhering to canons developed
through evolution.1
1. Use waste as a resource
2. Diversify and cooperate to fully use the habitat
3. Gather and use energy efficiently
4. Optimize rather than maximize
5. Use material sparingly
6. Don’t foul nests
15 7. Don’t draw down resources
8. Remain in balance with the biosphere
9. Run on information
10. Shop locally

1. J. M. Benyus, Biomimicry, Morrow, New York, 1997.

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 chapter 15: Design for Sustainability and the Environment 15-3

Absent from the list of principles for balancing biological ecosystems is the action of
inhabitants to restore resources. That role can only be filled by human inhabitants of
an ecosystem.

15.1.2 U.S. Environmental Movement

Throughout history there have been cases of naturalists, scientists, social workers,
and politicians who have publicized issues of sanitation and improper waste handling,
pollution, and conservation of natural resources (e.g., President Theodore Roosevelt).
However, efforts to alleviate problems associated with these issues usually came
only after their impact severely affected the population. Rachel Carson’s book Silent
Spring,1 published in 1962, is credited with raising awareness about beginning the
environmental movement in the United States. Silent Spring documented the negative
impact of pesticides, particularly DDT, on the environment. The title of the book proj-
ects the vision of a spring without the sound of birds.
The Environmental Protection Agency (EPA) was consolidated from smaller gov-
ernmental units into one agency by President Richard Nixon in 1970. The EPA is
endowed with the authority to write and enforce regulations based on legislation.
Several landmark pieces of environmental legislation were passed in the late 1960s
and 1970s. The EPA website (www.epa.gov) includes descriptions of all of the laws
and regulations created to protect human health and the environment. Most readers
will be familiar with a popular and voluntary program for encouraging energy effi-
ciency in consumer goods—Energy Star (www.energystar.gov). There is a rich litera-
ture base on the environmental movement in the United States2 and around the world.3

15.1.3 Measures of Environmental Impact

Today there are both public and private organizations with goals of preserving and
improving the environment for human habitation. These groups range in scale from
the local level to the national level and on to the international level. Environmental
Science and Environmental Engineering degree programs exist to train students in
history, science, policy, and design to mitigate environmental problems. Interdisci-
plinary sciences for the study of environmental issues are flourishing. A key concept
in environmental science is the quantification of the impact of humans and technol-
ogy on the environment. A simple equation was developed in the 1970s to model
the interaction of population with the environment.4 The factors in the equation are
15

1. R. Carson, Silent Spring, Houghton Mifflin, Boston, 1962.

2. See for example: P. Shabecoff, A Fierce Green Fire: The American Environmental Movement, Hill
and Wang, New York, 1993.
3. See for example: R. Guha, Environmentalism: A Global History, Oxford University Press, New Delhi,
2000.
4. M. R. Chertow, “The IPAT Equation and Its Variants,” Journal of Industrial Ecology, Vol. 4, pp. 13–29,
2000.

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without the prior written consent of McGraw-Hill Education.
 15-4 e ng i n e e r i ng d e s i g n

environmental impact (I ), population (P ), affluence1 (A), and technology (T). The re-
sulting IPAT equation is shown in Equation (15.1).

​I = P × A × T​ (15.1)

Allenby’s2 equation for the environmental impact is given by Equation (15.2).

resource use environment impact
​Overall Environment Impact = population × ​ ___________
    ​ _________________
× ​   
    ​​
person unit of resource use
(15.2)
Technology has come to represent the influence that man-made systems can have on
environmental impact. Strategies for reducing the overall environmental impact can
be interpreted directly from Equation (15.2). They are (1) reduce population or slow its
growth, (2) reduce the resource use per person, and (3) reduce the impact per unit of
resource. Designers and engineers will naturally focus on developing technology that
will reduce the unit of resource use in the equation.
The carbon footprint is another popular metric for measuring environmental
impact. The largest man-made contributor to greenhouse gases is carbon dioxide, CO2.
A metric for quantifying the amount of CO2 released into the atmosphere during any
activity is called the activity’s carbon footprint. The footprint includes the CO2 emis-
sion released by all production steps needed to create any product or process involved
in obtaining, refining, fabricating, packaging, transporting prior to putting the product
into use, and all activities needed to retire the product after it’s useful life. Water and
energy footprints are analogous metrics for products and processes. The term “carbon
footprint” was introduced in 1999 but is now in common usage.
In 2007 carbon footprint labels began appearing on some goods in Great Britain.3
The process to measure the carbon footprint is complex, and boundaries must be set
on how far back along the supply chain the calculation should be taken. The Inter-
national Standards Organization published in 2012 a standard for carbon footprinting
and updated it in 2018 (ISO 14067).4 One benefit of undergoing the carbon footprint
determination process is the focus it brings to the environmental impact of each step
of production.
It is no accident that the most popular metric for environmental impact is based
on carbon dioxide (CO2) emissions. Carbon dioxide is the most prevalent greenhouse
gas after water vapor and has the most harmful impact of the other greenhouse gases
(GHG). Carbon dioxide is generated by the combustion of fossil fuels—linking it
directly to the behavior of the human inhabitants of the biosphere. The fact that
climate change (formerly known as global warming) is a result of human habitation
15 has been widely accepted into our culture.

1. Affluence means a flow or supply of something. In the IPAT equation it usually means a measure
of value on a per-capita basis.
2. B. R. Allenby, Industrial Ecology: Policy Framework and Implementation. Prentice Hall, Upper
Saddle River, NJ, 1999.
3. “Following the Footprints,” The Economist Technical Quarterly, June 4, pp. 14–18, 2011.
4. International Standards Organization. Standard 71206. Web. 2018.

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 chapter 15: Design for Sustainability and the Environment 15-5

15.1.4 Dependence on Fossil Fuels

Modern society has been built with a dependence on fossil fuels: coal, oil, and natural
gas. The combustion of fossil fuels produces CO2, the chief constituent of GHG. In
addition to long-term costs, there is a growing recognition of the need to reduce de-
pendence on fossil fuels because of their impact on the environment.
In the past there were economic concerns about the stability of our energy supply
(specifically oil). The increase in environmental awareness in the 1970s coincided with
the first serious shock to the U.S. oil supply: the 1973 oil crisis. The 1973 oil crisis
was the first in a series of politically motivated disruptions of the oil supply. Disrup-
tions and price volatility can also be caused by natural disasters such as Hurricane
Katrina (2005) and technical disasters such as the Deepwater Horizon oil spill (2010).1
Now, oil supply disruptions pose less of a threat to the United States. This is
beneficial to sustainability goals. The United States is producing historically high
levels of fossil fuels due to new extraction methods (i.e., horizontal drilling, hydrau-
lic fracturing).2 Imports of crude oil are still needed due to a mismatch in domesti-
cally produced oil and current refineries, but the trend of crude oil production is
projecting energy independence.3 The U.S. Energy Information Administration (EIA)
predicts net energy exporter status in 2020 due to growth in natural gas and natural
gas plant liquids.4 The EIA also predicts reduction in coal and nuclear electricity
generation due to improved economics of alternative fuel sources.

15.1.5 Behavior Changes Started by the U.S. Environmental Movement

The environmental movement has great impact on changing attitudes and behaviors
of citizens, governments, and businesses. Environmental science principles are now
engrained in the education system and taught to children in K–12 classrooms. Elemen-
tary schoolchildren learn about GHG, threats to the ozone layer, and that some aerosol
sprays are not good for the planet. The habit of recycling household trash was born out
of the environmental movement.
Most U.S. citizens view recycling as separating their waste into different streams
as it comes out of their homes and businesses.5 The EPA tracks the generation of solid

1. Many believed nuclear power would undergo a major revival once the waste fuel storage problem
was clarified. Nuclear power does not produce greenhouse gases. However, the Fukushima Daiichi
nuclear disaster (March 11, 2011) brought the potential risks inherent with nuclear reactors to the
forefront of the public psyche. The nuclear plant failures were the result of the 2011 Tˉohoku 9.0 15
earthquake and subsequent tsunami. The future of nuclear power is therefore clouded.
2. “The National Academies Presents: What You Need to Know About Energy.” Needtoknow.nas.edu,
2019. Web. 14 June 2019.
3. R. Rapier, “No, The U.S. Is Not a Net Exporter of Crude Oil.” Forbes.com, 2018. Web. 14 June
2019.
4. U.S. Energy Information Administration, Annual Energy Outlook 2019 with Projections to 2050
(AEO2019), EIA, Washington, DC, 2019.
5. The United States has a history of recycling metals from their experiences in WWII.

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 15-6 e ng i n e e r i ng d e s i g n

Combustion Discards:
with Energy 137.7M
Recovery (52.5%)
Public
Recycling 33.4M

Number
Composting Landfills
67.8M Tons (12.7%)

Size
23.4M
(25.8%)
(8.9%)

Combustion
Other

29.7% Containers & packaging

Municipal Solid Waste 20.6% Durable Goods
262.4M Tons 19. 8% Nondurable Goods
15.1% Food Scraps
13.2% Yard Trimmings
<1.5% Other

FIGURE 15.1
2015 Data on disposition of municipal solid waste (MSW) in the United States.
From “Advancing Sustainable Materials Management: Facts and Figures Report | US EPA,” US EPA, 2019. Web.
13 June 2019.

waste and how it is handled using a mass balance methodology based on data from a
variety of sources including suppliers, industry associations, municipal governments,
and other agencies. Figure 15.1 displays a breakdown of the handling of municipal
solid waste throughout the United States in 2015.
U.S. government regulations continue to motivate businesses to modify produc-
tion methods to reduce the creation of harmful emissions into the air, the wastewa-
ter, and the solid waste. In many areas of environmental regulation Europe has
moved more aggressively than the United States. Because of world trade this has
required many U.S. companies to adopt their regulations. Engineers and designers
respond to these incentives by creating technology to reduce air, water, and solid
waste pollution. Section 15.5 discusses Design for the Environment (DFE) strategies
for creating products that align with the established goals of the environmental
movement.

15.2
15 SUSTAINABILITY

To sustain means to continue on into the future, usually without significant change.
Sustainability is a term that has come into popular culture as a characteristic of na-
tional fiscal policy, personal budgetary policy, and environmental policy. A formal
definition of sustainable development (used interchangeably with sustainability in
much of the literature) was established by a report titled, “Our Common Future,” from
the United Nations World Commission on Environment and Economic Development
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 chapter 15: Design for Sustainability and the Environment 15-7

(WCED).1 The report states: “Sustainable development is development that meets the
needs of the present without compromising the ability of future generations to meet
their own needs.”2 This is a statement of social equity for future generations. The
statement’s language is clear, but the true meaning and the interpretation require elab-
oration to extract operational principles.

15.2.1 WCED Report on Sustainability

In 1983 the UN General Assembly created the WCED to examine economic and en-
vironmental conditions to recommend strategies for managing global resources and
preserving the environment to meet the needs of the rapidly expanding population.
This commission was chaired by Gro Harlem Brundtland; its report, known also as
the “Brundtland Report,” was issued in 1987.
The WCED Report described characteristics of activities that would meet the
definition of sustainable and, by extension, contribute to sustainable development.
Critical objectives for environment and development policies that follow from the
concept of sustainable development include:
∙ Revive growth in an economic sense—This is particularly in developing countries
where increases in population represent unused human capacity.
∙ Change the quality of growth—Any activities undertaken for economic growth
must weigh expected financial gain against the impact on the environment and
human population.
∙ Meet essential needs for jobs, food, energy, water, and sanitation—This objective
is a restatement of Maslow’s most basic human needs with the addition of jobs
as an enabling condition. The WCED report further states that “overriding prior-
ity should be given” to meeting needs of the world’s poor.
∙ Ensure a sustainable level of population—Every ecosystem has an intrinsic limit
on the size of the population it can support.
∙ Conserve and enhance the resource base—The earth has sets of finite resources
(e.g., potable water, fossil fuels, and minerals), renewable resources (e.g., forests),
and, to some extent, unlimited resources (e.g., sunlight, air, and water). The best
way to conserve the resource base is to reduce per-capita consumption.
∙ Reorient technology and manage risk—The technology that defines the Anthro-
pocene age must be focused on solving problems of sustainability. It has been
acknowledged that technology in the developed world has caused many of the
sustainability problems. There are a large number of underdeveloped countries
that lack the resources (social and environmental) to move in the direction of
sustainability. Thus, the most economically vulnerable peoples of the world are 15
most at risk from environmental hazards.

1. The World Commission on Environment and Development, Our Common Future, Oxford University
Press, 1987.
2. The World Commission, op. cit., paragraph 1.

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 15-8 e ng i n e e r i ng d e s i g n

∙ Merge environment and economics in decision making—This objective is a direct

instruction to decision-makers. The WCED report declares that economic and eco-
logical goals are not naturally in opposition. However, the decision-making pro-
cess must be able to articulate and quantify the impacts of alternatives on a vastly
broader spectrum of objectives than required at the product level.
The themes of sustainability emerging from the WCED report can seem intimi-
dating and unrealistic to countries established on market-based economies and equal-
ity of opportunity as opposed to equality of outcome. The guidelines appear to
support the belief that sustainability will only be achieved by equalizing resource
consumption on a global basis and that the level of equilibrium will be below the
resource consumption currently enjoyed by several industrialized nations, a group
the largest of which is the United States. Another potentially unsettling aspect of the
sustainability movement to some in industrialized countries is that it is driven by
policymakers outside of their own sphere of political influence.

15.2.2 UN’s 2030 Agenda for Sustainable Development

Writers of the 1987 WCED Report gave a sense of urgency to the need for adoption
of recommended sustainable development guidelines. More than 30 years have passed
since that time, and indicators have not changed significantly. However, globalization
and global scale thinking are much more common. In addition, changes in means and
modes of communication (i.e., the Internet, social networking, mobile devices) have
served to raise awareness of disparities in socioeconomic status for people at both
ends of the spectrum.
The United Nations issued “Transforming Our World: The 2030 Agenda for
Sustainable Development” (A/RES/70/1) in 2015.1 The resolution included 17 sus-
tainable development goals (SDGs) to be reached by 2030. These goals cover the
dimensions of sustainable development—namely, economic, social, and environmen-
tal. Environmental goals include protecting ecosystems worldwide, maintaining water
and sanitation for all, providing access to clean energy for all people, and acting to
combat climate change. Social and economic dimensions of sustainability include
broad aspirational goals such as ending hunger and poverty, providing quality educa-
tion for all, and reducing inequality. UN resolutions do not have the force of law,
yet they influence government and corporate policy in many countries. McDonald’s
Corporation (the largest restaurant in the world) has linked its corporate sustain-
ability efforts to the UN SDG.2 As an example, McDonald’s has acted to increase
the sustainability of food packaging material. Over the years they have eliminated
15 foamed plastic containers and increased the use of recyclable and renewal materials
in their packaging. They are currently working on replacing plastic straws with other
materials (the paper straw is one possibility).

1 UN General Assembly, “Transforming Our World: The 2030 Agenda for Sustainable Development
(A/RES/70/1). Web. 13 June 2019.
2 “Contributing to the UN SDGs | McDonald’s.” Corporate.mcdonalds.com, 2019. Web. 13 June 2019.

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 chapter 15: Design for Sustainability and the Environment 15-9

15.3
CHALLENGES OF SUSTAINABILITY FOR BUSINESS

Protection of the earth’s environment is high on the value scale of most citizens of the
world’s developed countries. Investment firms now offer options of stocks and mu-
tual funds of companies that meet thresholds of corporate social responsibility (CSR).
Measures used to categorize firms based on CSR include (but are not limited to) envi-
ronmental performance based on impact reports of toxins and emission releases, regu-
latory compliance violations, and organization processes in place (e.g., environmental
management systems).1
Most corporations realize that it is in their best interest to take a strong pro-
environment approach to their business. Publically traded corporations include cor-
porate environmental goals and sustainability statements on their websites and in
their annual reports.2 Some provide additional detail on sustainability efforts. For
example, General Electric provides an annual citizenship report.3
Being pro-environment can have repercussions for the bottom line. Consider a
simple example of the creation of a new product with recycled content.
E X A M P L E 15.1

Typical letter-sized paper purchased for use in copiers is of 20 lb. weight and has a bright-
ness rating of 92, according to U.S. standards (100–104 Euro Bright scale). The online
retail price for one case (5000 sheets) of Staples® brand paper meeting these specifica-
tions in March 2020 was $51.69 for nonrecycled Staples Copy Paper.4 Costs for cases of
recycled paper meeting the same specifications were $56.59 for Staples 30% Recycled
Copy Paper and $68.49 for Staples 100% Recycled Copy Paper. This example illustrates
the impact that design for sustainability policies can have on a product’s quality and cost.
Example 15.1 illustrates the counterintuitive pricing reality for recycled paper. It costs
more than regular paper. The economic success of recycled paper relies on customers
choosing to pay a premium to support use of recycled content. However, not all recycled
products will be more expensive than their counterparts. Companies must develop sophis-
ticated decision-making strategies to predict accordingly. Companies must also continue
to develop improved processes to reduce the cost of including recycled content in goods.
Businesses operating in the United States necessarily adhere to all legislation,
including the growing body of environmental regulations. Companies with global
markets must also meet regulations in the countries of their markets. This may mean
creating product variants for different markets. Many corporations have an Environment
Health and Safety (EHS) unit that monitors environmental regulations in relevant
locations and develops strategies for dealing with differences in laws between coun-
tries. These groups must also review legislation developing in other countries that is 15
likely to influence the United States in the future.

1. M. Delmas and V. D. Blass, “Measuring Environmental Performance: The Trade-Offs of Sustainability

Ratings,” Business Strategy and the Environment, Vol. 19, pp. 245–260, 2010.
2. “Sustainability,” Stanley Black & Decker, 2011. Web
3. “Sustainable Growth: GE 2010 Citizenship Report,” General Electric, 2011. Web.
4. Prices found online at www.staples.com on March 1, 2020.

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without the prior written consent of McGraw-Hill Education.
 15-10 e ng i n e e r i ng d e s i g n

The sustainable development paradigm provides a new set of challenges to busi-

nesses by asserting that they are now accountable for three impacts of their actions—
environmental, social, and economic—on the population. If a corporation’s actions
would result in improvement on all three fronts at the same time, sustainable develop-
ment would be easy. However, corporate actions routinely are taken for the overall
economic benefit of their owners after taking into account primarily economic and
performance trade-offs.1 As public perception of the value of sustainability grows, some
corporations are finding that adherence to sustainability goals and guidelines can
improve their bottom line and spur innovation.2
The majority of sustainable development decision-making scenarios will include
some negative movement in one of the environment, economic, or social objectives. The
state of Cape Wind, a wind-power farm, provides an example of the difficult trade-offs
to businesses (and governments) when implementing sustainable development projects.

The Cape WindTM Project

Cape Wind was the name for the first off-coast wind farm proposed in the United States
in 2001. Cape Wind was planned to comprise 130 wind turbines, covering about 24
acres on Horseshoe Shoal, a shallow portion of the Nantucket Sound. The wind turbine
towers were to be about 258 feet high with base diameters of 16 feet. The propeller
tips would reach 440 feet from the water level. The farm was planned to be built for
maximum energy production of about 450 MW with an average of nearly 170 MW,
to offset the use of 113 million gallons of oil each year. The overall cost: $2.5 billion.
Massachusetts and federal government agencies gave approval and permits for
the project and the infrastructure required for Cape Wind’s development and use.
Some environmentalists opposed Cape Wind because of the projected negative im-
pact on fish, fishing, real estate, and tourism.
Robert F. Kennedy, Jr., a well-known environmental attorney of the time, wrote a
Wall Street Journal opinion3 calling the project a “rip-off,” as it would result in an esti-
mated cost to consumers of $0.25 per kilowatt hour (kwh) when hydropower was avail-
able from Quebec producers at $0.06 kwh. Kennedy claimed that a Massachusetts energy
company, NSTAR, was being pressured to agree to buy power from Cape Wind to meet
state regulations that utilities obtain 3.5 percent of their power from green sources. The
eCape website at that time provided many rebuttals to the K ­ ennedy editorial. One stated
the Massachusetts Department of Public Utilities estimated the impact of Cape Wind
product to average consumers would be $1.25 per month. A ­ nother rebuttal came from
the American Wind Energy Association (AWEA) blog4 in which the writer implied that
the need to develop wind power sources outweighed other economic considerations.
15
1. R. B. Pojasek, “Sustainability: The Three Responsibilities,” Environmental Quality Management,
Spring, pp. 87–94, 2010.
2. R. Nidumolu, C. K. Prahalad, and M. R. Rangaswami, “Why Sustainability Is Now the Key Driver
of Innovation,” Harvard Business Review, Vol. 87, pp. 56–64, 2009.
3. Robert F. Kennedy, Jr., “Nantucket’s Wind Power Rip-Off,” Wall Street Journal, Opinion Section.
Web. 18 July 2011.
4. T. Gray, “Why Cape Wind? Investing in America’s Energy Future Not Just Canada’s,” Into the Wind.
Web. 20 July 2011.

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 chapter 15: Design for Sustainability and the Environment 15-11

The Cape Wind example illustrates the complexities of corporations moving forward
on even the most seemingly advantageous sustainable development actions. These
projects are not always successful. The Cape Wind Project was discontinued in 2017.
Reasons for abandoning the project include termination of agreements to purchase the
farm’s electricity and harm to the area’s ecosystem and economics.1
The term triple bottom line (TBL) was first used by John Elkington in 1994.2
It is an accounting-like term to model the impacts of the three objectives of
sustainability: economics and environmental and social improvement.3 It is com-
mon to regard the TBL as a tool to measure impact on profits, planet, and people.
Elkington’s contention was that businesses should keep three separate balance
sheets, one for each set of stakeholders impacted by its actions. At the time it
was introduced, the TBL was not intended to be used to literally combine and
sum impacts on profits, planet, and people. It is likely that implementations of
the TBL will begin with a tool called a balanced scorecard, a way of assessing
performance toward targets on objectives on noncommensurate scales. General
Electric is one of the early adopters of the balanced scorecard approach to mon-
itoring progress on nonfinancial targets. GE’s 2010 Citizenship Report includes
an EHS Performance Against Commitments Table (p. 37), in which one row reads
as follows:

2010 Commitment: “Continue long-term GHG and energy use reduction trend and
drive to the following goals: 50% improvement in energy intensity by 2015.”
Progress: “GE continued to make progress on these goals; GHGs were reduced by
24% and energy intensity improved by 33% from the 2004 baselines.”
2011 Commitment: “Implement an ecomagination scorecard for GE’s internal envi-
ronmental footprint against which activities that drive the goals will be measured.”

This example provides an indication of how General Electric articulates its cor-
porate goals on environmental issues in a format that makes a statement about
sustainability.
GE set new baseline levels for measuring EHS performance. Through 2018 GE
has reduced GHG by 23 percent and overall freshwater use by 18 percent. This
indicates the level of commitment to sustainability.

15.4
END-OF-LIFE PRODUCT TRANSFORMATIONS

Essentially, all products, devices, and systems that will degrade throughout their 15
lifetime until they are no longer useful should be rendered into a form that supports
sustainability. Putting nonworking items into a landfill is the least desirable outcome.
Ashby puts it succinctly: “When stuff is useful, we show it respect and call it material.

1. “It’s Over: Cape Wind Ends Controversial Project.” Cape Cod Times.com, 2017. 14 June 2019.
2. J. Elkington, Cannibals with Forks: The Triple Bottom Line of 21st Century Business, Capstone, 1997.
3. “Triple Bottom Line,” The Economist, November 17, 2009.

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 15-12 e ng i n e e r i ng d e s i g n

End of Life

Reuse

Remanufacture

Recycle

Combustion

Energy
Landfill
Generation

FIGURE 15.2
Options for transformation at product end of life.

When the same stuff ceases to be useful, we lose respect for it and call it waste.”1
There are limited options for handling the waste of products that an end user no lon-
ger wants. The following are options available at a product’s end of useful life: reuse,
remanufacture, recycle, combustion, and landfill (Figure 15.2).

15.4.1 Reuse

Reuse means identifying a new end user who sees value in the product as it exists at
the time of the original user’s disposal. Allenby calls this point in a product life cycle
the “end of first life.” Proponents of capitalism point out that markets emerge when
there is a clear demand for the used product and a means for the buyer (first user) and
seller (next user) to communicate and exchange the product for cash or other goods.
Today there are more venues for the sale of used goods, either by the first-owner
or by an intermediary. They include garage sales, rummage sales (usually organized
by volunteer members of a nonprofit organization), and retail stores supported by
donations and run by charitable or philanthropic organizations (e.g., Goodwill Indus-
tries International and Habitat for Humanity operate stores for the sales of donated
15 used goods).
The Internet has provided for the expansion of the sales of used goods. One of
the most successful web-based organizations for used goods is eBay®. The eBay Inc.

1. M. F. Ashby, Materials and the Environment: Eco-Informed Material Choice, Elsevier, Boston, 2009,
p. 65.

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 chapter 15: Design for Sustainability and the Environment 15-13

corporation was founded in 1995 to create a global market to efficiently connect

buyers and sellers to promote sustainable commerce.1
Parts of an existing product can also be reused. This first requires the disas-
sembly of the disposed device and then the identification of a next user. In the case
of parts reuse, it is more common for the process to be initiated by a third party
who obtains the discarded device from the first owner. Reuse is common in the case
of rebuilt automotive parts. Construction materials such as bricks, hardwood floor-
ing, and wooden trim pieces can be sometimes recovered from home remodeling or
demolition sites.

15.4.2 Remanufacturing

An alternative to recycling is remanufacturing. Remanufacturing is the refurbishing

of an existing system by restoring it to near new condition. This process can be lim-
ited to the cleaning and replacement of worn parts (refurbishing) or the harvesting of
key subassemblies for placement into new parts. Remanufacturing saves energy by
reducing the need for the processing of raw materials into new products.
The refilling of inkjet cartridges is a common example of remanufacturing.
Office supply companies call this practice of returning the empty cartridges “recy-
cling,” but the process is a reconditioning of the product so that it can be restored
to its original use. In this instance, end users are surrendering their property (empty
or near-empty printer ink cartridge). There are drawbacks to the remanufacturing
process from the producer’s point of view: (1) It can cut into the new product mar-
ket share, and (2) the quality of the remanufactured product may be lower than that
of the original product. The latter concern may deter the OEM from engaging in
remanufacturing, leaving the market open for third parties. In other cases, OEM firms
remanufacture their own used goods such as copiers and printers (and sell them as
“refurbished”) and some larger engineered products such as diesel engines and con-
struction equipment.

15.4.3 Recycling

Recycling is the recovery from the waste stream, products, or goods that can be used in
the raw materials stream to make the same or similar material. Recycling is the end-of-
life strategy that is best suited for deriving profit from the waste stream. The benefits of
materials recycling are the contribution to the supply of materials, with corresponding
reduction in the consumption of natural resources, and the reduction in the volume of 15
solid waste. Moreover, recycling contributes to environmental improvement through
the amount of energy saved by producing the material from recycled (secondary) ma-
terial rather than primary sources (ore or chemical feedstock). Recycling requires

1. “Who We Are,” eBay Inc.com. Web.

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 15-14 e ng i n e e r i ng d e s i g n

energy, with its accompanying gas emissions, but recycle energy is small compared
with the original energy required to make the material. For example, recycled alumi-
num requires only 5 percent of the energy required to produce it from ore. Between 10
to 15 percent of the total energy used in the United States is devoted to the production
of steel, aluminum, plastics, or paper. Since most of this energy is generated from fos-
sil fuels, the reduction of carbon dioxide and particulate emissions due to recycling is
appreciable. Recycling of materials also directly reduces pollution. For example, the
use of steel scrap in making steel bypasses the blast furnace at a considerable economic
benefit. Bypassing the blast furnace in processing also eliminates the heavy pollution
associated with coke making.
The steps in recycling a material are (1) collection and transport, (2) separation,
and (3) identification and sorting.1

Collection and Transport

Collection for recycling is determined by the location in the material cycle where
the discarded material is found. Home scrap is residual material from primary mate-
rial production, such as cropped material from ingots or sheared edges from plates,
which can be returned directly to the production process. Essentially all home scrap
is recycled. Prompt industrial scrap or new scrap is that generated during the man-
ufacture of products, for example, compressed bundles of lathe turnings or stamping
discard from sheets. This type of scrap is sold directly in large quantities by the
manufacturing plant to the material producer. Old scrap is scrap generated from a
product that has completed its useful life, such as a scrapped automobile or refrig-
erator. These products are collected and processed in a scrapyard and sold to mate-
rial producers. The collection of recycled material from consumers can be a more
difficult proposition because the material is widely distributed. Materials can be
economically recycled only if an effective collection system can be established, as
with aluminum cans. Collection methods include curbside pickup, buy-back centers
(for some containers), and resource recovery centers where solid waste is sorted for
recyclables and the waste is burned for energy.

Separation
Separation of economically profitable recyclable material from scrap typically
follows one of two paths. In the first path, selective dismantling takes place. Toxic
materials such as engine oil are removed, and high-value materials such as gold and
copper are removed. Dismantling leads naturally to sorting of materials into like
categories. In the second path, the product is subjected to multiple high-energy
impacts to shred it into small, irregular pieces. For example, automobile husks are
15 routinely processed by shredding. Shredding creates a material form that assists in
separation. For example, ferrous material can be removed with large magnets, leav-
ing behind debris that must be disposed of, sometimes by incineration.

1. “Design for Recycling and Life Cycle Analysis,” Metals Handbook, Desk Edition, 2d ed., ASM
International, Materials Park, OH, 1998, pp. 1196–99.

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 chapter 15: Design for Sustainability and the Environment 15-15

Identification and Sorting

The economic value of recycling is largely dependent on the degree to which mate-
rials can be identified and sorted into categories. Material that has been produced by
recycling is generally called secondary material. The addition of secondary material to
virgin material in melting or molding can degrade the properties of the resultant material
if the chemical composition of the secondary material is not carefully controlled. For
example, in steel more than 0.20 percent copper or 0.06 percent tin cause cracking in
hot working. There is concern about buildup of these tramp elements as steel is recycled,
sometimes multiple times. Thus, the price of metal scrap depends on its freedom from
tramp elements, which is determined by the effectiveness of the identification and sepa-
ration process.
Degradation of plastics from secondary materials is more critical than in metals,
since it is often difficult to ensure that different types of polymers are not mixed
together. Only thermoplastic polymers can be recycled. Often, recycled material is
used for a less critical application than its original use. There is an intensive effort
to improve the recycling of plastics, and it is claimed that under the best of condi-
tions engineered plastics can be recycled three or four times without losing more
than 5 to 10 percent of their original strength.
Other materials that may not be recycled economically are zinc-coated steel
(galvanized), ceramic materials (except glass), and parts with glued identification
labels made from a different material than the part. Composite materials consisting
of mixtures of glass and polymer represent an extreme problem in recycling. Disposal
of polymer products without an attempt for recycling leads to a major environmen-
tal insult as an ocean clogged with discarded polymer products.
Practices of U.S. recycling were rocked in 2018 when China refused to buy waste
and plastics from other countries.1 The waste collection services to cities increased.
Separating recycling materials for sale was no longer profitable.2 Now more plastics
are going to the landfills for use as energy or as fill. China’s action will impact the
recycling of plastics with unknown impact.
Ferrous metals are separated from other materials by magnetic separation. For
nonferrous metals, plastics, and glass, separation is achieved by using such methods as
vibratory sieving, air classification, and wet flotation. Of particular concern is the recy-
cling of discarded electronic devices. Electronics scrap often contains very small quan-
tities of gold, silver, and copper. The variety of electronics components means that no
other method than hand sorting is practical. These need to be retrieved individually for
recycling.3

15

1 C. C. Katz, “Piling Up: How China’s Ban on Importing Waste Has Stalled Global Recycling.” Yale
E360, 2019. Web. 12 June 2019.
2 M. Corkery, “As Costs Skyrocket, More U.S. Cities Stop Recycling.” Nytimes.com, 2019. Web. 12
June 2019.
3. B. Hazelwood, M. G. Pecht, M. C. Sanchez, and D. K. Anand, The True Cost of Waste: Current
Issues in Electronic Waste, Center for Engineering Concepts Development Series (CALCE), Epic Press,
College Park, MD, 2018.

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 15-16 e ng i n e e r i ng d e s i g n

15.4.4 Combustion

Incineration reduces the volume of solid waste that goes to the landfill by burning
the combustible organic material. The combustion converts the retained energy of the
solid waste into heat, which can be used to generate steam and thus electricity. The
volume of solid waste is reduced by 50 to 95 percent depending on the effectiveness of
the sorting process. The outputs of the incineration process are ash (the noncombus-
tible inorganic waste), flue gases, and heat.
A modern municipal incineration plant employs considerable technology to per-
form its function without causing objectionable pollution. The combustion process
must be capable of handling a large flow of solid waste and produce controlled high
temperatures. The flue gas contains significant amounts of fine particulates in the
form of heavy metals, dioxins, furans, SO2, CO2, and HCl (all pollutants). Thus, it
is vital to control the flue gases by means of temperature control, particle filtration,
and gas scrubbers.

15.4.5 Landfill

A landfill1 is not a trash dump. A landfill is an airtight, lined (usually with polymer
sheeting), structured containment making for a permanent underground burial site
for compacted solid waste. The waste is set into the ground and isolated from the ele-
ments (e.g., air, rain, groundwater, and animals) so that it can remain in its original
form and decompose very slowly.2 Landfills literally fill in space to create more land
surface. Some landfills are enclosed in a clay liner that serves to separate the waste
more thoroughly from its physical surroundings.
The two challenges to maintaining a landfill are controlling leaching and meth-
ane gas. The penetration of some water into a landfill is inevitable. As water moves
through the waste, it is contaminated by organic material, metals, and products of
the slow decomposition to create a mixture of water and leachate. Landfills are built
with systems to direct leachate drainage into a collection pond where the contami-
nated water can be treated.
The trash in a landfill will decompose in an anaerobic process. This creates a
mixture of gases of about 50 percent methane and 50 percent carbon dioxide (both
greenhouse gases). These gases must be released through a piping system. In the
United States, solid waste landfills rank third in the source of human-related methane
gas emissions.
The gases produced by a landfill (LFG) can be used as an energy source.3 There
are methods to use LFG in combustion as a fuel for producing electricity and run-
15 ning some heavy equipment. Methane is the major component of liquid natural gas
and can be recovered from the LFG for separate use.

1. C. Freudenrich, “How Landfills Work,” 2008, http://science.howstuffworks.com.

2. A composting site is designed to decompose its waste quickly. This is the opposite of a landfill.
3. “Landfill Methane Outreach Program,” U.S. EPA, 2011. Web.

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 chapter 15: Design for Sustainability and the Environment 15-17

15.5
ROLE OF MATERIAL SELECTION IN DESIGN FOR ENVIRONMENT

Material selection has a unique role in Design for Environment tools, practices, and
methods. DFE methods are those that bring the consideration of the entire life cycle
of the product into the earliest stages of the design process. The material of which
a product is made greatly influences the impact of a product on the environment in
terms of natural resource use and end-of-life options.

15.5.1 Material Life Cycle

Materials have a life cycle that begins before the products in which they are used (see
Figure 1.7). A material’s life cycle begins with its removal from the earth and subse-
quent refining and shaping into engineering materials.
Designers can use their knowledge of materials and selection methods (see
Chapters 10 and 16) to make decisions as to which materials to use for a design once
the major details of the design are known.

15.5.2 Selection of Eco-Efficient Materials

Metallic and ceramic materials originate from minerals (ores) obtained from the earth,
which are refined using energy. Polymers are made from fossil fuel feedstock, chiefly
petroleum and natural gas, and require energy to turn them into engineering plastics.
We can divide the product life cycle into five phases: (1) material production,
(2) part manufacture, (3) transport between phases, (4) service in use, and (5) dis-
posal. Energy is consumed at each phase in this cycle, and some emissions are
produced (heat, liquids, solid wastes, and gases, chiefly CO2). Generally one of these
phases consumes the preponderance of the lifetime energy use. With the aluminum
beverage can it is the refining of aluminum from the bauxite ore (phase 1). With a
transport plane it is the jet fuel used in service (phase 4).
Materials selection plays a major role in each of the phases of product life cycle:
1. Material production: Reduce mass of material and choose material with low
eco-indicators.
2. Part manufacture: Select a process with low energy requirement and CO2
­footprint.
3. Transportation: Low mass reduces energy consumption.
4. Service in use: Thermal and electrical losses are often important and are material 15
dependent. Low mass is important in dynamic products (e.g., automobiles).
5. Disposal: High recyclability is a strong benefit and toxins must not be produced
during combustion or recycling processes.
Life-Cycle Assessment. A life-cycle assessment (LCA) is the ideal way to assess
alternatives in design for environment issues. The LCA determines all of the resource
consumption and emissions involved with a product, and then assesses the impacts in
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 15-18 e ng i n e e r i ng d e s i g n

terms of such categories as potential for global warming, ozone depletion, acidification
of streams and rivers, human toxicity, and so on. Creating an LCA is a resource-
intensive activity in terms of data collection and interpretation, requiring real expertise
in the field for meaningful results.1
Life-cycle assessment proceeds in three stages:
1. Inventory analysis: The flows of energy and materials to and from the product
during its life are determined quantitatively.
2. Impact analysis: All potential environmental consequences of the flows cata-
logued in step 1 are considered.
3. Improvement analysis: Results of steps 1 and 2 are translated into specific actions
that reduce the impact of the product or the process on the environment.
LCA is always preferred when making engineering decisions on existing products or
on a larger scale (e.g., factory remodeling). However, LCA is not well suited for mak-
ing decisions in the time frame needed in product-focused engineering design. As a
result, efforts have been made to find simple eco-indicators that could serve as useful
surrogates for an LCA.
A widely used factor in material selection in design is the embodied energy,
sometimes called the production energy. This is the energy per unit mass consumed
in making the material from its ores or feedstock. Values of embodied energy and
CO2 footprint, along with energies and footprints involved in manufacturing and
recycling, are given for 47 commonly used materials by Ashby.2
A second key eco-indicator is the carbon footprint, a measure of the carbon
dioxide in kilograms of gas produced per kilogram of material. Carbon dioxide is
chosen because of its great importance in global warming and climate change. By
multiplying the footprint by the annual world production we can rank the four worst
contributors of CO2 from material production:3 (1) steel, (2) aluminum, (3) cement,
and (4) paper and cardboard.
A number of methods and tools have been proposed for simplifying the LCA.4
One of the more useful and less complicated of these is the eco-audit method by
Ashby.5 An eco-audit is a scaled-down, simplified calculation to estimate environmen-
tal impact. Each of the five phases of product life cycle is evaluated for energy
requirements and CO2 production.
In the stage of manufacturing the parts, eco-indicators are those specific to the
manufacturing process under study. In the transport phase, energy consumed in trans-
portation is multiplied by the mass of the product. In the service-in-use phase, a
simple engineering model is constructed for the major energy-consuming activities

15
1. T. E. Graedel and B. R. Allenby, Design for Environment, Prentice Hall, Upper Saddle River,
NJ, 1996.
2. M. F. Ashby, op. cit., Chapter 12.
3. M. F. Ashby, Materials and the Environment, Butterworth-Heinemann, Boston, 2009, p. 118.
4. K. Ramani, D. Ramanujan, W. Z. Bernstein, F. Zhao, J. Sutherland, C. Handwerker, J-K. Choi,
H. Kim, and D. Thurston, “Integrated Sustainable Life Cycle Design: A Review,” Journal of Mechanical
Design, Vol. 132, p. 091004, 2010.
5. M. F. Ashby, op. cit., Chapter 7.

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without the prior written consent of McGraw-Hill Education.
 chapter 15: Design for Sustainability and the Environment 15-19

and their corresponding emissions. In the disposal phase, if the product is remanu-
factured or recycled there will be a negative value for the eco-indicator. A more
extensive collection of eco-properties can be found in the software CES EduPackTM
from Granta Design. The use of this software facilitates the preparation of eco-audits.

15.6
TOOLS TO AID DESIGN FOR THE
ENVIRONMENT AND SUSTAINABILITY

State-of-the art engineering design practice has been broadened to consider the prod-
uct as it will exist throughout its entire life cycle. Sustainability forces designers to
consider a product as having a first life cycle and then being retired in such as way
so that the used components or material can be transformed into new products. The
proliferation of Design for X (DFX) guidelines (see Section 8.12) is a well-known
phenomenon. No one resource can provide a definitive list of the guidelines, espe-
cially in a field as broad as Design for Sustainability and its subset Design for Envi-
ronment.1 Figure 15.3 provides a schematic diagram showing the relationship between

Quality of Life for

D

es
Stakeholders

ign
Design for

for Sustaina
Recycling
Design for the
Design for Environment
Assembly

Design Material
for Dis- Design for Re-
Selection for
b

manufacturing
ili

assembly Sustainability ty

15
FIGURE 15.3
Conceptual diagram of relationship of Design for Sustainability and other Design for X
topics.

1. M. Kutz, ed., Environmentally Conscious Mechanical Design, John Wiley & Sons, Hoboken, NJ,
2007.

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without the prior written consent of McGraw-Hill Education.
 15-20 e ng i n e e r i ng d e s i g n

s­ ustainability and the major DFX topics of this section. Several strategies are included
in this section and references are given for many others.

15.6.1 Design for Life Cycle

Design for Life Cycle emphasizes in embodiment design those issues that impact a
long, useful service life of the product. It also means designing for eventual replace-
ment or disposal. Design modifications that can keep a product in service will benefit
the environment in the long run because the product will not have to be disposed
of, and will not consume additional natural resources to be replaced. The following
life-cycle design strategies can be used to protect the environment and increase a
product’s sustainability.
∙ Minimize emissions and waste in the manufacturing process. Examine all of the
ways that the product negatively impacts the environment and eliminate or mini-
mize them using design. A polluting product is a defective product.
∙ Substitute recyclable materials where possible, and use design for disassembly
guidelines to improve chances for recycling.
∙ Increase the useful life of the product, thereby prolonging the time when new ma-
terial and energy resources need to be committed to a replacement of the prod-
uct. The useful life may be limited by degraded performance due to wear and
corrosion, damage (either accidental or because of improper use), or environmental
degradation. Other reasons to terminate the useful life not related to life-cycle is-
sues are technological obsolescence (something better has come along) or styling
obsolescence.
There are a variety of design strategies to extend a product’s useful life ap-
pearing in other sections of this text. A list locating the material can be found in
Table 8.6. D
­ esign for reliability (Chapter 13), durability (Chapter 13), and serviceabil-
ity (Chapter 8) are among them.

15.6.2 Design for Sustainability During Conceptual Design

New products need to meet the sustainability criteria as much as possible given the
state of technology, regulation, and business policy of the company. Design tools
and methods are being proposed to meet these criteria. It will be some time before
a definitive set of principles can be consolidated from the influx of new design aids.
Table 15.1 is a set of proposed guidelines for design that would meet the environmen-
15 tal objectives of sustainability as described by the Brundtland Report in Section 10.2.
Many new methods for sustainable design are adaptations of existing methods (e.g.,
design for analogy1).

1. D. P. Fitzgerald, J. W. Herrmann, and L. C. Schmidt, “A Conceptual Design Tool for Resolving

Conflicts Between Product Functionality and Environmental Impact,” Journal of Mechanical Design,
Vol. 132, p. 091006, 2010.

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 chapter 15: Design for Sustainability and the Environment 15-21

TABLE 15.1
Suggested Sustainability Design Guidelines for Conceptual Design

Proposed Design Guideline Sample Products

1. Minimize quantity of resource use by ∙ Tankless water heaters (heat water as it is
optimizing its rate and duration demanded)
∙ Low-flow (or time-limited) shower heads
2. Incorporate automatic or manual tuning ∙ Clothes dryers with moisture sensors
capabilities ∙ Multiflush toilets
∙ Programmable thermostats
3. Use feedback mechanism to inform end user ∙ Temperature probes with readouts in ovens
of current status of process
4. Create separate modules for behaviors with ∙ Hybrid-electric vehicles
conflicting requirements
Adapted from C. Telenko and C. C. Seepersad, “A Methodology for Identifying Environmentally Conscious Guide-
lines for Product Design,” Journal of Mechanical Design, Vol. 132, p. 091009, 2010.

15.6.3 Design Guidelines Applying to Embodiment Design

1. Design for the minimal use of materials and energy. First, achieve minimum
weight without affecting quality, performance, and cost. Automotive manufacturers
have made it a long-term goal to achieve greater fuel economy and have done so with
weight reduction (often by substitution of materials). Second, reduce waste of all types:
scrap in manufacture, defective components in assembly, damaged goods in shipping.
Thus, good design for quality practice will invariably result in a reduction in material
consumption. Third, look hard at the design and use of packaging. Recognize changes
in polymer packaging materials that allow for the recovery, recycling, and reuse of pack-
aging materials. The substitution of cardboard for Styrofoam in fast-food packaging is a
common example. Look for ways to design shipping containers so they can be reused.
2. Design for Disassembly. Remanufacture, reuse, and recycling require the ability
to economically remove the most valuable components when the product reaches
the end of its useful life.
∙ M inimize the number of adhesive and welded joints when it makes sense.
∙ Use removable fasteners and those that are not prone to breakage (i.e., avoid
snap fits).
∙ Increase the corrosion resistance of fasteners.
3. Design for Maintainability. Most products need to be opened to be maintained. 15
Thus, maintainability guidelines include the previous category of Design for Dis-
assembly and Design for Serviceability (see Section 8.9.4).

15.6.4 Design Guidelines Applying to End-of-Life Transformations

Engineers design products and systems for a certain behavior during their use-
ful life. Design for the Environment or Green Design, or eco-design, or design for
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 15-22 e ng i n e e r i ng d e s i g n

sustainability requires designing a product or system for a particular behavior at the

end of its useful life. These design approaches are not necessarily aligned with perfor-
mance, which requires the design team to have expertise in the planned transforma-
tion of the product at the end of its first useful life (see Section 10.4).
1. Design for Remanufacturing. One challenge to remanufacturing is that the origi-
nal product was not designed with this goal in mind. Not every product is a good
candidate for remanufacturing. An MIT group studied 25 products and found that
the energy used to remanufacture them was typically less than to create new prod-
ucts, as expected. Yet the remanufactured products were likely to be less efficient
in energy use than new products or their replacement versions. In about half of the
cases studied, there were no net energy savings; in the other half the savings were
minimal.1
Characteristics of products that are good candidates for remanufacturing
include the following:2
∙ Technology that will be relevant (stable) for 7 to 10 years
∙ Product redesign cycle of 1 to 4 years
∙ Rate of return for remanufacture at 15 percent or more (an option some com-
panies employ)
∙ 50 to 75 percent of parts to be remanufactured
∙ Modular architecture with good separation of materials into different modules
Guidelines to employ while originally designing a product that may be
remanufactured are as follows:
∙ Increase damage resistance throughout life cycle.
∙ Make location of wear detectable.
∙ Use components that can be assembled by commonly available tools.
∙ Eliminate part features that can collect dirt and debris.
Unfortunately, some of these guidelines are contrary to guidelines for good
Design for Assembly and a trade-off decision is necessary.
2. Design for Recycling. There are several steps that the designer can follow to en-
hance the recyclability of a product.
∙ Make it easier to disassemble the product and thus enhance the yield of the
separation step.
∙ Minimize the number of different materials in the product to simplify the
identification and sorting issue.
15

1. “When Is It Worth Remanufacturing?” Advanced Materials and Processes, July, p. 14, 2011.
2. P. Zwokinski and D. Brissaud, “Remanufacturing Strategies to Support Product Design and Redesign,”
Journal of Engineering Design, Vol. 19, pp. 321–355, 2008; B. Bras, “Design for Remanufacturing
Processes,” in M. Kutz, ed., Environmentally Conscious Mechanical Design, John Wiley & Sons,
Hoboken, NJ, 2007.

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without the prior written consent of McGraw-Hill Education.
 chapter 15: Design for Sustainability and the Environment 15-23

∙ Choose materials that are compatible and do not require separation before
recycling (e.g., a bronze bushing embedded in a steel part will cause severe
processing difficulty during hot working recycled steel).
∙ Identify the material that the part is made from right on the part. Use the identi-
fication symbols for plastics.
Applying these guidelines can require serious trade-offs. Minimizing the number
of materials in the original product may require a compromise in performance
from the use of a material with less-than-optimum properties. A clad metal sheet
or chromium-plated metal provides the desired attractive surface at a reasonable
cost, yet it cannot be readily recycled. In the past, decisions of this type would
be made exclusively on the basis of cost.
3. Design for waste recovery and reuse in processing. The waste associated with
a product can be a small fraction of the waste generated by the processes that
produced the product. Be alert to ways of reducing process waste. Avoid the use
of hazardous or undesirable materials. Keep current on changes in government
regulations and lists of hazardous materials. For example, avoid the use of CFC
refrigerants, use aqueous solvents for cleaning instead of chlorinated solvents, and
use biodegradable materials when possible.

15.7
SUMMARY

The question arises, What is the impact of sustainability on the average design engi-
neer? The answer depends on the type of business in which the engineer is employed.
If it is an industry that is heavily impacted by governmental regulations such as oil
production, chemicals, or automobiles, then regulations that are intended to protect
the environment or safety of the public already strongly influence products design
or manufacturing operations. If it is in the business of energy production, there is no
question that major changes will take place as fossil fuels become depleted and global
warming becomes more widely recognized as a threat to life on our planet. These will
present major challenges and opportunities for design engineers. Many other busi-
nesses recognize the importance of sustainability and view it as an opportunity to dif-
ferentiate their products as green products. Thus, the design engineer can be assured
that sustainability, and its engineering embodiment, design for the environment, will
be of increasing importance into the future.
It is generally believed that improvement of the environment is the joint responsi-
bility of all citizens in partnership with business and government. Government plays
a crucial role, usually through regulation, to ensure that all businesses share equitably 15
in the cost of an improved environment. Since these increased product costs often
are passed on to the customer, it is the responsibility of government to use the tool of
regulation prudently and wisely. Here the technical community can play an impor-
tant role by providing fair and timely technical input to government. Finally, many
visionaries see a future world based on sustainable development in which the world’s
resources will no longer be depleted because the rate of resource consumption will be
balanced by the rate of resource regeneration.
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without the prior written consent of McGraw-Hill Education.
 15-24 e ng i n e e r i ng d e s i g n

NEW TERMS AND CONCEPTS

Carbon footprint IPAT Remanufacturing
Ecosystem Life-cycle assessment Reuse
Embodied energy Municipal solid waste Sustainability
Environmental impact Recycling Triple bottom line

BIBLIOGRAPHY

“20 Years: Into Our Common Future,” Environment, 50(1), 46–59, 2008.
Allenby, B. R.: The Theory and Practice of Sustainable Engineering, Prentice Hall, Upper
Saddle River, NJ, 2011.
Ashby, M. F.: Materials and the Environment: Eco-Informed Material Choice, Elsevier,
­Boston, 2009.
Azapagic, A. and P. Slobodan: Sustainable Development in Practice: Case Studies for
Engineers and Scientists, 2d ed., John Wiley & Sons, New York, 2011.
de Steiguer, J. E.: The Origins of Modern Environmental Thought, University of Arizona
Press, Tucson, 2006.
Graedel, T. E. and B. R. Allenby: Design for Environment, Prentice Hall, Upper Saddle River,
NJ, 1996.
Kates, R. W., T. M. Parris, and A. A. Leiserowitz: “What Is Sustainable Development?,”
Environment, 47(3), 8–21, 2005.
Kutz, M. ed.: Environmentally Conscious Mechanical Design, John Wiley & Sons, Hoboken,
NJ, 2007.

PROBLEMS AND EXERCISES

15.1 Count the number of light bulbs in your residence. Calculate the power use for a day.
What is the power difference between using incandescent and fluorescent bulbs in your
residence for a year? Where can you safely dispose of the fluorescent bulbs?
15.2 Example 15.1 gives the current cost for standard size and quality copy paper with
varying levels of recycled material content. Do further research to see what differences
in the production of the paper lead to the cost differences.
15.3 Write an essay answering the question, Is Walmart’s business practice of locating in
small communities a good example of sustainable development?
15.4 There has been a major shift toward outsourcing manufacturing from the United States
to foreign countries. One unintended consequence of this situation is the appearance of
counterfeit parts. This has occurred in both electrical components and mechanical parts.
Find an example of this phenomenon and write a brief essay.
15
15.5 Use the concept of a force field diagram (Chapter 3) to show the main factors that help
and hinder the reduction of the use of energy in product development. (Hint: A “help”
would be miniaturization; a hindrance would be increasing world wealth.)
15.6 Enthusiastic environmentalists often take the position that in the interest of saving the
world, products should be designed to be as durable as possible, with major emphasis
on modularity so that worn parts can be easily replaced. Discuss the advantages and
disadvantages of this approach to design for the environment.
Copyright 2021 © McGraw-Hill Education. All rights reserved. No reproduction or distribution
without the prior written consent of McGraw-Hill Education.