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chapter/One Sustainable Design, Engineering,and Innovation

Julie Beth Zimmerman and James R. Mihelcic

Thischapterdiscusses the evolution of protecting human health and the environment from regulatory approachesto sustainable development, high- lighting critical opportunities for engineers to design appropriate, resilient solutions. Definitions for sustainable development and design are presented. Several emerging topics are

presented—greenchemistry,biomimicry,greenengineering,lifecyclethink- ing, and systems thinking—offeringenhancements to engineering funda- mentals leading to rigorous and sustainable design solutions.

#

Z i u t o

g r a f / i S t o c k p h o t o

Chapter Contents

1.1 Background: Evolution from

Environmental Protection to

Sustainability

1.2 The Path Forward:

Operationalizing Sustainability

1.3 Engineering for Sustainability

1.4 Measuring Sustainability

1.5 Policies Driving Green

Engineering and Sustainability

1.6 Designing Tomorrow

Learning Objectives

1. Describe the evolution of the protection of human health and theenvironment from regulatory approaches to sustainability.

2. Relate The Limits to Growth, “The Tragedy of the Commons,”and the definition of carrying capacity to sustainabledevelopment.

3. Define sustainability, sustainable development, andsustainable engineering in your own words and according toothers.

4. Redefine engineering problems in a balanced social, economic,and environmental context.

5. Apply life cycle thinking and systems thinking to problemdefinition and the design and assessment of proposedsolutions.

6. Differentiate between traditional indicators and sustainabilityindicators that measure progress toward achieving the goal of sustainability.

7. Describe several frameworks for sustainable design andunderstand the importance of design and innovation inadvancing sustainability.

8. Discuss the role of regulations and other policy tools, such as

voluntary programs, in advancing environmental and humanhealth protection as well as sustainability.

1


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administrator, who is appointed by the president and approved byCongress, leads the agency.

The EPA has its headquarters in Washington, D.C., regional officesfor each of the agency’s 10 regions (Figure 1.1) and 27 researchlaboratories. EPA is organized into a number of central program

offices as well as regional offices and laboratories, each with its own

Application /1.2 The Basics of EPA Related Laws and Regulations

The EPA has many tools to protect human health andthe environment, including partnerships, educationalprograms, and grants. However, the most significanttool is writing regulations, which are mandatoryrequirements that can be relevant to individuals, busi-

nesses, state or local governments, nonprofit organiza-tions, or others.

The regulatory process begins with Congress pass-ing a law and then authorizing the EPA to help putthat law into effect by creating and enforcing regula-tions. Of course, there are many checks and balancesalong the path from law to regulation, including

public disclosure of intent to write or modify a regu-lation, and a public comment period where thosepotentially affected by the regulation have an oppor-tunity to offer input to the process.

Draft and final federal regulations are published in

the Code of Federal Regulations (CFR). The number 40that is associated with environmental regulations (i.e.,40CFR) indicates the section of the CFR related to theenvironment.

SOURCE: http://www.epa.gov/lawsregs/basics.html

ND

SD

MN

WIMI

NY

NJ

OH

VA

PA

WV

DC

MD

DE

CT

Rl

MA

MEVT

NH

IL IN

OKAR

LATX

AK

8

6

7

5

3

4

2

9

9

10

2

110

NM

PR

VI

FL

GAAL

TN

MS

SC

NC

KY

HI

Guam

Trust Territories

American Samoa

Northern Mariana

islands

CO

UT

AZ

NV

ID

OR

WA

CA

IANE

KS MO

MT

WY

Figure / 1.1 The EPA’s Ten Regions Each region has its own regional administrator andother critical functions for carrying out the mission of protecting human health and theenvironment. EPA headquarters are located in Washington, D.C.

(Adapted from EPA).

1.1 Background: Evolution from Environmental Protection to Sustainability 3


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regulatory, research, and/or enforcement mandate. The agency con-ducts environmental assessment, research, and education. It has theresponsibility of maintaining and enforcing national standards under avariety of environmental laws, in consultation with state, tribal, andlocal governments. It delegates some permitting, monitoring, andenforcement responsibility to U.S. states and Native American tribes.EPA enforcement powers include fines, sanctions, and other measures.

The agency also works with industries and all levels of government in awide variety of voluntary pollution prevention programs and energyconservation efforts.

The mission of EPA is to protect human health and the environment.EPA’s purpose is to ensure that:

all Americans are protected from significant risks to human healthand the environment where they live, learn, and work;

national efforts to reduce environmental risk are based on the bestavailable scientific information;

federal laws protecting human health and the environment areenforced fairly and effectively;

environmental protection is an integral consideration in U.S. policiesconcerning natural resources, human health, economic growth,energy, transportation, agriculture, industry, and international trade,and these factors are similarly considered in establishingenvironmental policy;

all parts of society—communities, individuals, businesses, and state,local, and tribal governments—have access to accurate informationsufficient to effectively participate in managing human health andenvironmental risks;

environmental protection contributes to making our communitiesand ecosystems diverse, sustainable, and economically productive;

the United States plays a leadership role in working with other

nations to protect the global environment.

EPA works closely with the states to implement federal environ-mental programs. States authorized to manage federal programs musthave enforcement authorities that are at least as stringent as federallaw. EPA works with officials in state environmental, health, andagricultural agencies on strategic planning, priority-setting, and mea-surement of results.

While we have made tremendous strides in addressing the mostegregious environmental insults and maintained a growing economy,the environmental challenges of today are more complex and subtlethan encountered at the start of the modern environmental movement.For example, there are clear connections between emissions to air, land,and water even if the regulations were not written and the EPA was not

organized with these considerations.Furthermore, air and water emissions come from many distributed

sources (referred to as nonpoint source emissions), so it is muchmore difficult to identify a specific source that can be regulated and

The Regulatory Processhttp://www.epa.gov/lawsregs/regulations/index.html

Access the Code of FederalRegulationshttp://www.gpoaccess.gov/cfr/

4 Chapter 1 Sustainable Design, Engineering, and Innovation


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Sperm Whales Killed (thousands)

25And nowthe sperm

whale is beinghunted without

limit onnumbers—theultimate folly.

20

15

10

1

0

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Fin Whales Killed (thousands)

They switched

to killing

fin whales.

30

25

20

15

10

5

0

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Sei Whales Killed (thousands)

As fin stockscollapsed, they

turned to sei whales.

0

5

10

15

20

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Worldwide Total of Whales Killed (thousands)

Since 1945,more and

more whaleshave been

killed to

produce . . .

65

55

45

35

25

15

5

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Worldwide Whale Oil Production (millions of barrels)

Less andless oil.

3

2

1

0

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Blue Whales Killed (thousands)

35

30

25

20

15

10

5

0

First, the industrykilled off the

biggest whales—the blues.

Then the 1940s,as stocksgave out . . .

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Average Gross Tonnage of Catcher

Boats (hundreds of tons)

7

6

5

4

3

2

Catcher

boats have

becomebigger...

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

Average Horsepower of Catcher

Boats (thousands)

2.5

2.0

1.5

1.0

And morepowerful

. . .

Average Production per Catcher Boat

per Day’s Work (barrels of whale oil)

150

130

110

90

70

50

30

1 9 3 0

1 9 3 5

1 9 3 8

1 9 4 0

1 9 4 5

1 9 5 0

1 9 5 5

1 9 6 0

1 9 6 5

1 9 7 0

But theirefficiency

hasplummeted.

Figure / 1.2 Limits to Growth and Technology of the Whaling Industry Maintaininggrowth in a limited system by advances in technology will eventually result in extinction for

both whales and the whaling industry. As wild pods of whales are destroyed, finding thesurvivors has become more difficult and has required more effort. As larger whales are killed off,smaller species are exploited to keep the industry alive. Without species limits, large whales arealways taken wherever and whenever encountered. Thus, small whales subsidize theextermination of large ones.

(Based on Payne, R. 1968. “Among Wild Whales.” New York Zoological Society Newsletter (November)).



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(Application 1.5). In 1986, the UN World Commission on Environmentand Development released Our Common Future. This book is also

referred to as the Brundtland Commission report, because Ms. GroBrundtland, the former prime minister of Norway, chaired the com-mission. The Brundtland Commission report defined sustainabledevelopment as “development which meets the needs of the presentwithout compromising the ability of the future to meet its needs.”

This report helped to prompt the 1992 UN Conference on Environ-ment and Development, known as the Earth Summit, held in Rio de Janeiro, Brazil. The conference, the first global conference to specificallyaddress the environment, led to the nonbinding agenda for the 21stcentury, Agenda 21, which set forth goals and recommendations relatedto environmental, economic, and social issues. In addition, the UNCommission on Sustainable Development was created to oversee theimplementation of Agenda 21.

At the 2002 World Summit on Sustainable Development in Johan-nesburg, South Africa, world leaders reaffirmed the principles of sustainable development adopted at the Earth Summit 10 years earlier.They also adopted the Millennium Development Goals (MDGs),listed in Table 1.1. The eight MDGs represent an ambitious agendafor a better world that can guide engineering innovation and practice.This is a good example of the link between policy and engineering:policy can drive engineering innovation, and new engineeringadvancements can encourage the development of new policies withadvanced standards that redefine “best available technologies.”

1.2 The Path Forward: Operationalizing Sustainability

Given the many definitions of sustainability (refer back to Applica-tion 1.5) and the complexity of a systems perspective to include thelinkages and feedback between the environment, economy, and soci-ety, there are ongoing efforts to move from discussions to operationally

Application /1.5 Defining Sustainability

If you Google the words sustainability, sustainable devel-opment, and sustainable engineering, you will get hun-dreds of definitions. Try it! The abundance of varyingdefinitions has made it difficult to realize consensus onwhat sustainability is. However, nearly all of the defi-

nitions of sustainability refer to integrating the threeelements of the triple bottom line (environment, econ-omy, society). Most definitions also extend sustainabil-ity criteria to include the aim of meeting the needs of current and future generations.

Sustainability is defined by Merriam-Webster asfollows: (1) of, relating to, or being a method of harvest-ing or using a resource so that the resource is not

depleted or permanently damaged and (2) of or relatingto a lifestyle involving the use of sustainable methods.

Sustainable development is defined by the Brundt-land Commission as “development which meets theneeds of the present without compromising the ability

of the future to meet its needs.”Sustainable engineering is defined as the design of

human and industrial systems to ensure that human-kind’s use of natural resources and cycles do not lead todiminished quality of life due either to losses in futureeconomic opportunities or to adverse impacts on socialconditions,humanhealth, and the environment(Mihelcicet al., 2003).

Class DiscussionIn which of the MDGs do

engineers have a role toplay? Are these traditional

or emerging roles for engineers to

play in society and practice?

Millennium Development GoalsYou can go to www.un.org/millenniumgoals/ Go to this URL tolearn more about progress towardmeeting the MDGs.



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Table / 1.1

MillenniumDevelopment Goals (MDGs) MDGs are an ambitious agenda embraced by the world community for reducing poverty and improving lives of the global community. Learn more at www.un.org/millenniumgoals/.

Mill ennium Devel opment Goal Background Example Target (s) (of 21 total targets)

1. Eradicate extreme

poverty and hunger.

More than a billion people still live

on less than $1 a day.

(1a) Halve the proportion of people living on less

than $1 a day and those who suffer from hunger.

2. Achieve universalprimary education.

As many as 113 million children donot attend school.

(2a) Ensure that all boys and girls completeprimary school.

3. Promote gender equalityand empower women.

Two-thirds of illiterates arewomen, and the rate of employment among women is two-thirds that of men.

(3a) Eliminate gender disparities in primary andsecondary education, preferably by 2005, and atall levels by 2015.

4. Reduce child mortality. Every year, nearly 11 million youngchildren die before their fifth

birthday, mainly from preventableillnesses.

(4a) Reduce by two-thirds the mortality rateamong children under 5 years.

5. Improve maternal health. In the developing world, the risk of

dying in childbirth is one in 48.

(5a) Reduce by three-quarters the ratio of women

dying in childbirth.6. Combat HIV/AIDS,

malaria, and otherdiseases.

40 million people are living withHIV, including 5 million newlyinfected in 2001.

(6a and 6c) Halt and begin to reverse the spreadof HIV/AIDS and the incidence of malaria andother major diseases.

7. Ensure environmentalsustainability.

768 million people lack access tosafe drinking water and 2.5 billionpeople lack improved sanitation.

(7a) Integrate the principles of sustainabledevelopment into country policies and programsand reverse the loss of environmental resources.

(7b) Reduce by half the proportion of peoplewithout access to safe drinking water.

(7c) Achieve significant improvement in thelives of at least 100 million slum dwellers.

8. Develop a globalpartnership for

development.

(8a) Develop further an open, rule-based,predictable, nondiscriminatory trading and

financial system.(8b) Address the special needs of the least-developed countries.

(8c) Address the special needs of landlockedcountries and small island developing states.

(8d) Deal comprehensively with the debtproblems of developing countries throughnational and international measures to makedebt sustainable in the long term.

(8e) In cooperation with pharmaceuticalcompanies, provide access to affordable,essential drugs in developing countries.

(8f) In cooperation with the private sector, makeavailable the benefits of new technologies,especially information and communications.

SOURCE: www.un.org/millenniumgoals/.

1.2 The Path Forward: Operationalizing Sustainability 9


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applying a sustainability framework to organizational and engineeringactivities. There are often considered to be two broad classes of effortsto operationalize sustainability: top-down and bottom-up. That is, onestrategy involves high-level decision-makers initiating activities andestablishing organizational structures and incentives to push sustain-ability into the organization from the top. In the other strategy, peoplethroughout the organization are motivated to pursue their functions ina more sustainable manner and drive sustainability into the organiza-tion through grassroots initiatives and self-initiated activities.

There are examples of successful changes from governmental and

nongovernmental organizations as well as major corporations that have been realized from both of these approaches, but the most successfulexamples are when all levels of the organization are working towardsustainability outcomes. A successful example of this evolution tooperationalize sustainability can be seen in the Path Forward at theOffice of Research and Development at the EPA (described in Appli-cation 1.6).

Once there is an intention to pursue sustainability, there is a clearneed to identify an approach to problem solving that is evolved fromprevious approaches which had not systematically incorporated triple bottom-line considerations. There are two critical frameworks that can be utilized to support the expanded view necessary to move towardsustainability goals: life cycle thinking and systems thinking. Whilethese two frameworks are related, there are clear differences where life

cycle thinking is focused on material and energy flows and the subse-quent impacts, while systems thinking can also capture the relationshipof political, cultural, social, and economic considerations, and potentialfeedbacks between these considerations and material and energy flows.

Figure / 1.4 Daily Activity in Much of the World of Collecting Water.

(Photo courtesy of James R. Mihelcic).



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1.2.1 LIFE CYCLE THINKING

Life cycle thinking supports recognizing and understanding how bothconsuming products and engaging in activities impact the environmentfrom a holistic perspective. That is, life cycle considerations take intoaccount the environmental performance of a product, process, orsystem from acquisition of raw materials to refining those materials,manufacturing, use, and end-of-life management. Figure 1.5a depictsthe common life cycle stages for a consumer product. In the case of engineering infrastructure, Figure 1.5b depicts the life cycle stages of:(1) site development, (2) materials and product delivery, (3) infra-

structure manufacture, (4) infrastructure use, and (5) end-of-life issuesassociated with infrastructure refurbishment, recycling, and disposal.In some cases, the transportation impacts of moving between these lifecycle stages are also considered.

There is a need to consider the entire life cycle, because differentenvironmental impacts can occur during different stages. For example,some materials may have an adverse environmental consequence whenextracted or processed, but may be relatively benign in use and easy torecycle. Aluminum is such a material. On one hand, smelting of alumi-num ore is very energy intensive. This is one reason aluminum is afavored recycled metal. However, an automobile will create the bulk of its environmental impact during the use life stage, not only because of combustion of fossil fuels, but also because of runoff from roads and theuse of many fluids during operation. And for buildings, though a vast

amount of water, aggregate, chemicals, and energy goes into the pro-duction of construction materials, transport of these items to the job site,and construction of a building, the vast amount of water and energyoccurs after occupancy, during the operation life stage of the building.

Application /1.6 The Path Forward at EPA’s Office of Research and Development(Anastas, 2012)

Since 2010, significant changes have been made toEPA’s research enterprise. All of EPA’s actions anddecisions are based on science and research. The EPAhas recently embarked on a major effort to realign itsresearch portfolio in order to more effectively addresspressing environmental challenges and better serve theAgency’s decision-making functions into the futureusing sustainability as an organizing principle.

In 2010, EPA commissioned a landmark study fromthe National Academies to provide recommendationson how to systematically operationalize the concept of sustainability into the Agency’s entire decision mak-ing. The final report entitled “Sustainability and theU.S. EPA” (also known as the “Green Book”) outlinedseveral recommendations, including identification of

key scientific and analytical tools, indicators, metrics,and benchmarks for sustainability that can be usedto track progress toward sustainability goals. EPAscientists have begun to develop the scientific andanalytical tools that will be needed in order to respondto and implement sustainability at EPA, including lifecycle assessment, ecosystem services valuation, fullcost/full benefit accounting, green chemistry, greeninfrastructure, and more. This effort to develop thetools of sustainability mirrors past EPA efforts todevelop the tools for assessing, evaluating, and man-aging risk.

Accessthe “GreenBook” (Sustainability at the U.S.EPA)athttp://www.nap.edu/catalog.php?record_ id¼13152#toc

LCA 101http://www.epa.gov/nrmrl/std/lca/lca.html



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Figures 1.5a and 1.5b also show, as feedback loops, the potential forrecycling, remanufacturing, and reuse. While there are often benefitsassociated with these various end-of-life handling strategies, they canalso carry environmental impacts and should be included when mak-ing design or improvement designs and in life cycle considerations.

Further, and potentially most importantly, life cycle thinking will

minimize the possibility of shifting impacts from one life cycle stage toanother by considering the entire system. Forexample, efforts to reducethe energy demands of lighting led to the installation of millions of compact fluorescent light bulbs (CFLs) (Application 1.7). However,

Materialextraction

(a)

(b)

Materialprocessing

Sitedevelopment

Infrastructuremanufacture

Materials andproduct delivery

Infrastructureuse

Recycle Remanufacturing Reuse

End of life

Recycle

Productuse

Reuse

End of lifeManufacturing

Remanufacturing

Figure / 1.5 Common Life Cycle Stages The most common life cycle stages for(a) a manufactured product and (b) engineered infrastructure.

The Life Cycle Initiativehttp://lcinitiative.unep.fr/



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CFLs contain a small amount of mercury. By focusing solely on reducingenergy demand and carbon emissions, while not considering the toxicityassociated with manufacturing and disposing of CFLs, there is the poten-tial to have a greater environmental and human health impact associatedwith the mercury, a heavy metal with known neurotoxic effects.

By using life cycle thinking, one canbegin to understand and evaluatethese potential trade-offs across many environmental and human healthendpoints such as energy use, carbon emissions, water use, eutrophi-cation, solid waste production, and toxicity by tracking all of the materialand energy inputs associated with not just using energy for lighting butproducing and disposing of light bulbs. These trade-offs can be quantif-ied through a tool known as life cycle assessment (LCA).

Life cycle thinking supports the goal of improving the overallenvironmental performance of an engineering design and not simplyimproving a single stage or endpoint while shifting burdens elsewherein the life cycle. To effectively capture these impacts across the entire

Application /1.7 Energy Conservation, Reduced Carbon Emissions, and New LightingTechnology

Given the growing concern about the impact of increas-ing carbon emissions on temperature and climate, thereare many strategies proposed to improve energy effi-ciency, thereby reducing the associated carbon emis-sions. Electricity production creates about 33 percentof total carbon emissions, while 27 percent of the totalcarbon emissionsresult from transportation. Residentialelectricity is about 33 percent of total electricity (withapproximately one-thirdfor industrial and one-thirdforcommercial uses). According to the U.S. Energy Infor-mation Administration, the average U.S.householduses10,000 kWh a year, of which 8.8 percent, or 940 kWh, islighting.

One effort that has been largely adopted is to reducethe amount of energy, and subsequently carbon emis-sions, associated with lighting. The United States, andmany other countries, are currently phasing out sales of

incandescent light bulbs forgeneral lighting. Theaim is toforce the use and technological development of moreenergy-efficient lighting alternatives, such as CFLs andlight-emitting diode (LED) lamps.

A 100 W incandescent light bulb that runs 3 h a dayevery day will use around 100 kWh a year. A high-efficiency light uses about one-fourth of the energy of aconventionalbulb.Replacing the100 W bulb with a 25WCFL would thus save 75 kWh a year. This reduction inelectricity usecorresponds to a savings of about 150lb of carbon dioxide (the same as emitted by burning 7.5gallons of gasoline). Given that 19 percent of global

electricity generation is taken for lighting, there is thepotential for tremendous savings associated with newalternative lighting technologies.

However, it is important to note that current CFLscontain approximately 4.0 mg of mercury per bulb,raising environmental and human health concerns. Fur-ther, initially there were performance considerationsassociated with CFLs that have led to resistance in themarket, including lighting quality and warm-up time.While mercury is not used in the manufacture of LED bulbs, there are still life cycle impacts associated withtheir production, use, and disposal. However, LEDlamps solve many of the performance considerationsassociated with CFLs. To make the situation even morecomplex, thecostof CFLs and LEDs is higherthanthat of incandescent light bulbs. Generally, this extra cost isrepaid in the long term, as both lighting technologies

use less energy and have longer operating lives thanincandescent bulbs.

From this discussion, there are clear opportunities toimprove the energy consumption, and subsequent carbon emissions, associated with lighting. However, thetechnological advances present some trade-offs interms of mercury use and disposal and performancefor CFLs and cost for both CFLs and LEDs. These trade-offs need to be considered and quantified for informeddecision making in the present and should be used toguide future design and innovation for improved light-ing technologies in the future.

Class DiscussionHow should decisions be

made concerning thesetypes of trade-offs (i.e.,

mercury use for carbon reduction)?Is this a societal decision? Shouldthese decisions be made bycompanies alone or with publiccomment? At what scale—local,national, international? How do wesystematically weight one potentialimpact for a potential benefit?



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life cycle of the product, process, or system, one must consider theenvironmental impacts for the entire life cycle through an LCA.

An LCA is a sophisticated way of examining the total environmentalimpact through every life cycle stage. The LCA framework is depictedin Figure 1.6. LCAs can be used to identify processes, ingredients, andsystems that are major contributors to environmental impacts, comparedifferent options within a particular process with the objective of

minimizing environmental impacts, and compare two different prod-ucts or processes that provide the same service.

As shown in Figure 1.6, the first step in performing an LCA is todefine the goal and scope. This can be accomplished by answering thefollowing questions:

What is the purpose of the LCA? Why is the assessment beingconducted?

How will the results be used, and by whom?

What materials, processes, or products are to be considered?

Do specific issues need to be addressed?

How broadly will alternative options be defined?

What issues or concerns will the study address?

Another item that needs to be addressed at this stage is to define thefunction and functionalunit. Thefunctional unit serves as the basis of theLCA,the system boundaries, and the datarequirements and assumptions.For example, if you were interested in determining the energy use andassociated carbon emissions from reclaiming or desalinating water (overthe complete life cycle), the function would be to reclaim treated waste-water or desalinate ocean water. The associated functional unit mighttherefore be m3 of reclaimed wastewater or m3 of desalinated water.

Once the goal, scope, and functional unit have been defined, the nextstep of an LCA is to develop a flow diagram for the processes being

evaluated and conduct an inventory analysis. This involves describing allof the inputs and outputs (including material, energy, and water) in aproduct’s life cycle, beginning with what the product is composed of,where those materials came from, where they go, and the inputs andoutputs related to those componentmaterials during theirlifetime. It is alsonecessary to include theinputs and outputs duringthe product’s use, suchas whether the product uses electricity or batteries. If the analysis strictlyfocusesonmaterials anddoes notconsider energyor other inputs/outputs,it is referred to as a subset of LCA and materials flow analysis.

A materials flow analysis (MFA) measures the material flows into asystem, the stocks and flows within it, and the outputs from the system.In this case, measurements are based on mass (or volume) loadingsinstead of concentrations. Urban materials flow analysis (sometimesreferred to as an urban metabolism study) is a method to quantify

the flow of materials that enter an urban area (e.g., water, food, andfuel) and the flow of materials that exit an urban area (e.g., manufac-tured goods, water and air pollutants including greenhouse gases, andsolid wastes) (Application 1.8).

Goal andscope

definition

Inventoryanalysis

Impactassessment

Interpretation

Figure / 1.6 Components of theLife Cycle Assessment (LCA)Framework.



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e xampl e / 1 . 1 Determining Function and Functional Unit in Terms of LCA

example 1If you are asked to conduct an LCA on two different laundry detergents, what could you use as thefunctional unit for the analysis?

sol u t i on 1The basis of the LCA could be the weight or volume of each laundry detergent necessary to run 1,000washing machine cycles. (This says nothing about the performance of the laundry detergents—howclean the clothes are after washing—as that is assumed to be identical for the purpose of the LCA.)

example 2If you are asked to conduct an LCA on paper versus plastic grocery bags, what could you use as thefunctional unit for the analysis?

sol u t i on 2

The basis of the LCA could be a set volume of groceries to be carried, in which case two plastic bagsmight be equivalent to one paper bag. Or the functional unit could be related to the weight of groceriescarried, in which case you would need to determine whether paper or plastic bags are stronger and howmany of each would be needed to carry the specified weight.

Application /1.8 Urban Metabolism and a Case Study on Hong Kong

Urban metabolism studies are important, becauseplanners and engineers can use them for recognizingproblems and wasteful growth, setting priorities, and

formulating policy. For example, a materials flowanalysis performed over 10 years on the quantity of freshwater that enters and exits the Greater TorontoArea found that water inputs had grown 20 percentmore than the outputs. Possible explanations for thiscould be leaking water distribution systems, com- bined sewer overflow events, and increased use of water for lawn care, all of which would allow inputtedwater to bypass output monitoring. The analysis alsopointed to a need to further develop water conserva-tion because of a fixed availability (or storage capac-ity) of freshwater.

Figure 1.7 shows the results of a materials flowanalysis performed on the city of Hong Kong. Here,

69 percent of the building materials were used forresidential purposes, 12 percent for commercial, 18percent for industrial, and 2 percent for transport

infrastructure. Also, a 3.5 percent measured increasein materials useover the 20-year study period indicatedthat Hong Kong was still developing into a larger urban

system.During the study period, the city’s economy shifted

from manufacturing to a service-based center. Thisresulted in a 10 percent energy shift from the industrialsector to the commercial sector, yet energy consumptionrose. The large increase in energy use was attributed toincreases in development and residential/occupationalcomfort and convenience. The rate of use of consumablematerials also rose during the study period, with plasticsactually increasing 400 percent.

Overall air emissions in Hong Kong decreased;however, air pollutants associated with motor vehi-cle use and fossil fuel power production (such as NOxand CO) increased. Land disposal of solid waste rose

by 245 percent, creating a dilemma for the space-limited city. Although a large portion of this waste isconstruction, demolition, and reclamation waste,



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municipal solid waste also rose 80%, with plastics,food scraps, and paper contributing the most tomunicipal waste.

Though the overall rate of growth for water usedeclined over the study (10–2 percent) from decreasesin agriculture and industrial use, the per capita fresh-water consumption rose from 272 to 379 L/day. Wateris one of the major waste sinks for the city, due to itslarge volume of untreated sewage. Biochemical oxygendemand (BOD) loadings increased by 56 percent. Nitro-gen discharges also increased substantially. Sewagecontamination in Hong Kong waters is now considered

a major crisis for the city, having large harmful environ-mental, economic, and health effects.

One conclusion is that, at its current urban meta- bolic rate, Hong Kong is exceeding its own natura lproduction and CO2 fixation rates. Materials andenergy consumption in the city greatly outweighthe natural assimilation capacity of the local eco-system. High urban metabolism rates show that,relative to other cities, Hong Kong is more efficient(on a per capita basis) in land, energy, and materialsuse due to lower material stocks in buildings andtransportation infrastructure, has less energy andmaterials use (domestic consumption), and hashigher proportions of space dedicated to parks and

open space.

HC

Freshwater

2,501,370

Cargo in

People in

322,392

144,601

Cargo out

People out

186,910

14,500

2,000,000560

Wastewater

BODs

Pb TSPs

Export:

Liquid fuels Solid fuels Materials: Domestic solid waste:

Export:Glass

Plastics

Wood

Iron and steel

17,187 Glass

Iron and steel

Cement

Wood

Plastics

Paper

Glass

Wood

Iron and steel

Paper

Food

Plastics

Other

240

100

240

1,740

2,050

1,160

1,230

363

7,240

9,822

2,095

3,390

2,768

16,668

12,101

494

Human food

Animal food

Paper

Cement

Liquid

Solid fuels

Human food

348

14,387

7,001

11,749

8,956

2,059

24,838

12

10.005

296 269 364 107 0.05 35

CO SO2 NO2

Figure / 1.7 Important Materials Flows into and through the City of Hong Kong All unitsare in tonnes per day. Arrows are intended to give some indication of the direction of flow of materials.

(Adapted from AMBIO: A Journal of the Human Environment , Vol. 30, K. Warren-Rhodes and A. Koenig, “Escalating Trendsin the Crash. Urban Metabolism of Hong Kong: 1971–1997,” pages 429–438, 2001, with kind permission of SpringerScienceþBusiness Media B.V.)

Application /1.8 (continued)



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The purpose of an inventory analysis—either a full life cycle orlimited to materials—is to quantify what comes in and what goes out,including the energy and material associated with each stage in the lifecycle. Inputs include all materials, both renewable and nonrenewable,and energy. It is important to remember that outputs include thedesired products as well as by-products and wastes such as emissionsto air, water, and land. It is also important to consider the quality of data

for inputs and outputs to the system when conducting an inventoryanalysis.

The third step in an LCA (or MFA) is to conduct an impact assess-ment. This step involves identifying all the environmental impactsassociated with the inputs and outputs detailed in the inventoryanalysis. In this case, the environmental impacts from across the lifecycle are grouped together in broad topics. Environmental impacts caninclude stressors such as resource depletion, water use, energy use,global warming potential, ozone hole depletion, human toxicity, smogformation, and land use. This step often involves some assumptionsabout what human health and environmental impact will result from agiven emission.

The final step in the impact assessment can be controversial, as itinvolvesweighting these broad environmental impact categories to yield

a single score for the overall environmental performance of the product,process, or system being analyzed. This is often a societal considerationthat can vary between cultures. For example, Pacific Rim Island nationsmaygive greater weighting to climate change giventheir vulnerabilitytosea levelrise, whileother countriesmay givegreaterweighting to humanhealthimpacts. This suggeststhat thetotalimpact score maybe distorted by weighting factors. It also means that for an identical life cycleinventory, the resulting decisions from the impact assessment mayvary from country to country or organization to organization.

Ultimately, LCA (and MFA) can provide insight into opportunitiesfor improving the environmental impact of given product, process, orsystem. This can include choosing between two options or identifyingareas for improvement for a single option. LCA and MFAare extremely

valuable in ensuring that environmental impact is being minimizedacross the entire life cycle and that impacts are not being shifted fromone life cycle stage to another. This leads to a system that is globallyoptimized to reduce adverse effects of the specified product, process, orsystem.

1.2.2 SYSTEMS THINKING

Beyond tracking the physical inputs and outputs to a system, systemsthinking considers component parts of a system as having addedcharacteristics or features when functioning within a system ratherthan in isolation. This suggests that systems should be viewed in aholistic manner. Systems as a whole can be better understood when thelinkages and interactions between components are considered in addi-

tion to understanding the individual components. An example of the benefit of using life cycle thinking and systems thinking for the issue of assessing the potential environmental impact of biofuels is presented inApplication 1.9.

Applying Life Cycle Thinking toInternational Water andSanitation Development Projectshttp://usfmi.weebly.com/thesesreports.html

Class DiscussionAre biofuels sustainable?

From a life cycle andsystems perspective,

biofuels may make sense from acarbon perspective, but what otherendpoints may be critically importantto their successful implementation?Can these tools help to evaluate theimpacts of biofuels on foodavailability and pricing?



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The nature of systems thinking makes it extremely effective forsolving the most difficult types of problems. For example, sustain-ability challenges are quite complex, depend on interactions andinterdependencies, and are currently managed or mitigated throughdisparate mechanisms. In this way, policies or technologies may beimplemented with well-articulated goals, but can lead to unintendedconsequences because all of the potential system feedbacks were not

considered.One way to begin a systems analysis is through a causal loop

diagram (CLD). CLDs provide a means to articulate the dynamic,interconnected nature of complex systems. These diagrams consistof arrows connecting variables (things that change over time) in away that shows how one variable affects another. Each arrow in aCLD is labeled with an s or o. An s means that when the first variablechanges, the second one changes in the same direction. (For example,increased profits lead to increased investments in research and devel-opment.) An o means that the first variable causes a change in theopposite direction of the second variable. (For example, more greenengineering innovations can lead to reduced environmental andhuman health liabilities.)

In CLDs, the arrows come together to form loops, and each loop is

labeled with an R or B (Figure 1.9). R means reinforcing—that is, thecausal relationships within the loop create exponential growth orcollapse. For instance, Figure 1.9 shows that the more fossil fuel– based energy consumed, the more carbon dioxide that is emitted, asthe global temperatures increase, and the more energy that needs to be consumed. B means balancing—that is, the causal influences in theloop keep the variables in equilibrium. For example, in Figure 1.9,the more profits generated by a company, the more research anddevelopment investments that can be made, which will lead to

Application /1.9 Life Cycle and Systems Thinking Applied to Biofuels

A recent example where the relevance of life cyclethinking and systems thinking was made clear wasthe proposal to use biobased fuels to replace a portionof the U.S. transportation fuel portfolio. There has beensignificant emphasis placed on alleviating dependenceon fossil fuel by producing fuel energy from agricul-tural products. One of the clearest examples of this isthe emphasis in the United States on producing ethanolfrom corn. Whether the economics of producing etha-nol from corn is considered by monetizing life cycleemissions or direct environmental impacts (includingwater, fertilizer, and pesticide application), corn-basedethanol may require (per unit of fuel produced) more

fossil fuel and fertilizer inputs that emit large amountsof greenhouse gases, particulate matter, and nutrientsthan the current petroleum-based production.

This is not to suggest that producing energy from biobased resources is not an appropriate or ulti-mately sustainable strategy. It is rather to suggestthat pursing renewable energy in a way that onlyaddresses the singular goal of reducing use of finiteresources can lead to increased environmental andhuman health impacts and even greater stress on theearth’s systems without using life cycle and systemsthinking frameworks. Figure 1.8 shows the environ-mental impact of biofuels created from differentcrops sources. Note how this supposed “greener”fuel can have significant and varied environmentalimpacts across the life cycle. These impacts are also

highly dependent on the feedstock choice and produc-tion location.



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ECOSYSTEMS

Rapeseed, IP, CH

Rapeseed, D

Soy, Brazi l

Soy, U.S.

Jatropha, extensive, India

Jatropha, intensive, India

Jatropha, hedge, East Africa

Environmental impacts relative to petrol, CH-mix

1 6 7 %

Oil palms, Malaysia

Oil palms, Colombia

Petrol, CH-mix

G l o b

a l w a

r m i n g

p o t e n

t i a l

F r e s h w a t e r

e u t r o

p h i c a

t i o n

O z o n e d

e p l e t i o n

F r e s h w a t e r

e c o t o

x i c i t y

H u m a

n t o x i c i t y ,

c a n c e r

e f f e c t s

H u m a

n t o x i c i t y ,

n o n c a n c e r e f f

e c t s

W a t e r

r e s o u r c

e d e p l e t i o n

L a n d

u s e

M i n e

r a l , f o s s i l a

n d r e n e w a b l e

r e s o u

r c e d e p l e t i o

n

B I O D I E S E L

F O S S

I L

HUMANHEALTH

RESOURCES

Figure / 1.8 Overview of the Diversity of Environmental Effects from VariousRenewable Feedstocks for the Production of Biodiesel Environmental impacts arereported relative to the production of petroleum-based petrol mix with lighter shadingindicating less impact and darker shading indicating greater impact than the conventionalsystem. Based on material from the Seattle Post-Intelligencer (2008).

Application /1.9 (continued)



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more green engineering innovations, reducing the number of envi-ronmental and human health liabilities, which leads to greaterpotential profits.

CLDs can contain many different R and B loops, all connected witharrows. Drawing these diagrams can develop a deep understandingof the system dynamics. Through this process, opportunities forimprovements will be highlighted. For example, the links betweenfinite resource consumptionfor energy production, carbon emissions,andglobal temperaturesmay lead us to findnew sources of renewableenergy.

Further, it is through systems thinking that we can also begin tounderstand the resilience of a system. Resiliency is a very importantconcept for sustainable systems because it is the capacity of system to

survive, adapt, and grow in the face of unforeseen changes, evencatastrophic incidents (Fiksel, 2003). Resilience is a common feature of complex systems, such as companies, cities, or ecosystems. Given theuncertainty and vulnerability around sustainability challenges suchas climate change, water scarcity, and energy demands, sustainabledesigns likely will need to incorporate resilience as a fundamentalconcept.

The idea of designing engineered systems for resilience would be tointroduce more distributed and/or smaller systems that can continue toeffectively function in uncertain situations with greater resilience. Exam-plesinclude power generationand rainwater harvestingat thehouseholdor community level, and decentralized wastewater treatment. Again, it isnecessary to consider the life cycle impacts of the entire system whendesigning a new, distributed system with more redundancy to replace a

more centralized system. This is in order to understand the potentialtrade-offs between environmental and human health impacts for resil-iency gains. This is wherethe lifetime of a givensystem becomes a crucialfactor in LCA.

Globaltemperature

Carbon dioxideemissions

Fossil-basedenergy

consumptionR B

Research anddevelopmentinvestments

s o

s o

Environmentaland human

health liabilities

Green engineeringinnovations

Profits

s

ss

Figure / 1.9 Examples of Reinforcing and Balancing CLDs Each arrow in a CLD is labeledwith an “s” or an “o”. An s means that when the first variable changes, the second one changes inthe same direction. An o means that the first variable causes a change in the opposite direction of the second variables. R means reinforcing—that is, the causal relationship within the loop tocreate exponential growth or collapse. B means balancing—that is, the casual influences in theloop keep variables in equilibrium.



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1.3 Engineering for SustainabilityEngineers, in particular, have a unique role to play in the Path Forwardto a sustainable future. This is because they have a direct effect on thedesign and development of products, processes, and systems, as well ason natural systems through material selection, project siting, and theend-of-life management of chemicals, materials, and products. Engi-

neers play a significant and vital role in nearly all aspects of our lives.They provide basic services such as water, sanitation, mobility, energy,food, health care, and shelter, in addition to advances such as real-timecommunications and space exploration. The implementation of all of these engineering achievements can lead to benefits as well as problemsin terms of the environment, economy, and society. The adverseimpacts of traditional engineering design, often implemented withouta sustainability perspective, can be found all around us in the form of water use inefficiencies, depletion of finite material and energyresources, chemicals with unintentional toxicity impacts, and degrada-tion of natural systems.

Engineers must develop and implement solutions with an under-standing of the potential benefits and impacts over the lifetime of thedesign. In this way, the traditions of innovation, creativity, and bril-

liance that engineers use to find new solutions to any challenge can beapplied to designing sustainable solutions—that is, solutions that notonly address grand societal challenges but also are in, and of them-selves, sustainable by not creating legacy adverse impacts on the

e xampl e / 1 . 2 Distributed Systems That May Improve Functionality and ResilienceProvide an example of a distributed system composed of independent yet interactive elements that maydeliver improved functionality and greater resilience. What are the potential benefits in terms of sustainability?

solutionA collection of distributed electric generators (for instance, fuel cells) connected to a power grid may bemore reliable and fault-tolerant than centralized power generation (Fiksel, 2003). The sustainability benefits may include the following:

Reduced resources necessary for transmission and distribution

Reduced losses due to long-distance transmission and distribution, so less total energy needs to begenerated to provide the same amount to the end user

Possible credit given to owner for net reductions in area emissions

Lower overall emissions if distributed energy source is cleaner than alternative (e.g., fuel cells, landfillgas recovery, biomass)

Potential for reduced emissions by producing energy only to meet current demand (much moreflexibility in production levels with distributed systems)

Green Chemistryhttp://www.epa.gov/greenchemistry

1.3 Engineering for Sustainability 21


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Application /1.11 Examples of Green Chemistry

The fundamental research of green chemistry has been brought to bear on a diverse set of challenges,including energy, agriculture, pharmaceuticals andhealth care, biotechnology, nanotechnology, consumerproducts, and materials. In each case, green chemistry

has been successfully demonstrated to reduce intrinsichazard, to improve material and energy efficiency,and to ingrain a life cycle perspective.

Some examples of green chemistry that illustrate the breadth of applicability include:

a dramatically more effective fire extinguishingagent that eliminates halon and utilizes water incombination with an advanced surfactant;

production of large-scale pharmaceutical activeingredients without the typical generation of

thousands of pounds of toxic waste per poundof product;

elimination of arsenic from wood preservativesthat are used in lumber applied to household

decks and playground equipment; introduction of the first commodity bio-based

plastic that has the performance qualities neededfor a multimillion pound application, as a foodpackaging;

a new solvent system that eliminates large-scaleultrapure water usage in computer chip manufac-ture, replacing it with liquid carbon dioxide,which allows for the production of the next gen-eration of nano-based chips.

Application /1.12 Examples of Biomimicry

Three levels in biology can be distinguished fromwhich innovative and sustainable technology can bemodeled:

Mimicking natural methods of manufacture of chemical compounds to create new ones

Imitating mechanisms found in nature (e.g.,velcro)

Studying organizational principles from social behavior of organisms, such as the flocking behavior of birds or the emergent behavior of bees and ants

Pigment-Free Color: There can significant environmen-tal impacts associated with dyes, inks, coatings, andpaints. Looking to natural systems for ideas of how tocreate color, one quickly finds that nature uses struc-ture rather than pigment to offer the brilliant hues seenon butterflies, peacocks, and hummingbirds. The colorsseen result from light scattering off regularly spacedmelanin rods and interference effects through thinlayers of keratin. Qualcomm is mimicking this strategy

to create screens for electronic devices.Preservatives: Oneof the emerging chemical classes of

concern areanti-microbialsusedin a range of applications

from personal care products to industrial systems. Using biomimicry as a tool, one would look for organisms thatinherently demonstrate this desirable trait. For example,red and green algae produce halogenated metabolites,primarilyutilizing bromide, that have demonstrated anti-microbial activity. Based on this approach, Nalco devel-oped a product, StabrexTM, a chlorine alternative tomaintaining industrial cooling systems.

Clean without chemicals: There are many environ-

mental and human health concerns associated withcertain classes of detergents and soaps. So how doesnatureprovide the service of cleanliness without poten-tially toxic chemicals? One example to consider howthe lotus plant that prevents dirt from interfering withphotosynthesis. Lotus leaves have rough hydrophobicsurfaces that allow dirt to be carried away by drops of water that “ball up” and roll off the surface. A numberof new products have emerged based on this “lotus-effect,” including Lotusan paint that provides a similarmolecular-structure to the lotus leaf such that dirt iscarried away by the rain providing “self-cleaning” building exteriors.

Examples are based on Biomimicry: Innovation Inspired byNature, Janine M. Benyus, with permission of Harper-Collins Publishers.



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1.3.2 THE IMPORTANCE OF DESIGN AND INNOVATIONIN ADVANCING SUSTAINABILITY

Embedded in the discussion of sustainability and engineering is theword design. Design is the engineering stage where the greatest influ-ence can be achieved in terms of sustainable outcomes. At the designstage, engineers are able to select and evaluate the characteristics of thefinal outcome. This can include material, chemical, and energy inputs;effectiveness and efficiency; aesthetics and form; and intended specifi-cations such as quality, safety, and performance.

The design state also represents the time for innovation, brainstorm-ing, and creativity, offering an occasion to integrate sustainability goalsinto the specifications of the product, process, or system. Sustainabilityshould not be viewed as a design constraint. It should be utilized as anopportunity to leapfrog existing ideas or designs and drive innovativesolutions that consider systematic benefits and impacts over the life-time of the design.

This potential is shown in Figure 1.10. This figure demonstrates thatallowing an increased number of degrees of freedom to solve achallenge, address a need, or provide a service creates more designspace to generate sustainable solutions.

For a given investment (time, energy, resources, capital), potential benefits can be realized. These benefits include increased market share,reduced environmental impact, minimized harm to human health, andimproved quality of life. In the case in which constraints requiremerely optimizing the existing solution or making incrementalimprovements, some modest gains can be achieved. However, if thedegrees of freedom within the design space can be increased, more benefits can be realized. This is because the engineer has an

Learn more about the theory ofleapfrog or disruptive innovationhttp://blogs.hbr.org/video/2012/03/disruptive-innovation-explaine.html

Class DiscussionWhat is an example of

leapfrog or disruptiveinnovation that had a

positive impact towardsustainability? What are thepotential trade-offs of full-scale

implementation of this innovation?

Class DiscussionAre there toxic chemicals

used in nature? How arethey “managed”? What

lessons can we mimic from how toxicchemicals are generated or used innatural system for industrialsystems?

Redefine

theproblem

Reengineerthe system

Optimize theexisting solution(incrementalism)

Investments (time, money, resources, energy)

P o t e n t i a l b e n e f i t s

Figure / 1.10 Increasing Potential Benefits with Increasing Degrees of Design Freedom for a

Given Investment Note that allowing an increased number of degrees of freedom to solve aproblem frees up more design space to innovate and generate sustainable solutions.



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opportunityto designa newsolution that may appearvery differentinform but provides the same service. This may pose challenges if thenew design is too embedded into an existing and constrained system.Ultimately, the most benefits can be achieved when the engineerdesigns with the most degrees of freedom—at the highest systemscale—toensure that each component within the system is sustainable,performs with the other system components, and meets the overall

intended purpose.

e xampl e / 1 . 3 Degrees of Freedom and Sustainable DesignIn 2004, the average miles per gallon for a car on the road in the United States was 22. In response toconcerns about global climate change, policy makers and engineers are working toward a more innova-tive technical and management strategies to improve gas mileage and lower carbon dioxide emissions.What are the design opportunities for improvement scaled with increasing degrees of freedom andwhat are the potential benefits?

solutionTable 1.2 gives three design solutions. As the degrees of freedom in the design increase, engineers inthis example have more flexibility to innovate a solution to the problem.

Table / 1.2

ThreeDesignSolutions Investigated in Example 1.3

Increasing degrees of freedom

I nc re men ta lI mpr ove me nt Ree ngin eer the System Redefi ne the System Boun dar y

Design

solution

Improve the efficiency of the

Carnot engine; use lighter-weight materials (compositesinstead of metals)

Use a hybrid electric or fuel cell

system for energy; change theshape of the car for improvedaerodynamics; capture waste,heat, and energy for reuse

Meet mobility needs without

individual car; implement apublic transit system; designcommunities so commercialdistricts and employment arewithin walking and cyclingdistance; provide access todesired goods and serviceswithout vehicular transportation

Potentialrealized

benefits

Moderate fuel savings;moderate reductions in CO2emissions

Improved fuel savings; improvedreductions in CO2 emissions;improved material and energyefficiency

Elimination of theenvironmental impactsassociated with the entireautomobile life cycle; maximizedfuel savings and CO2 reductions;improved infrastructure; denserdevelopment (smart growth);improved health of society fromwalking and less air pollution



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The design phase also offers unique opportunities in the life cycle of

an engineered product, process, or system. As shown in Figure 1.11, it isat the design phase of a typical product that 70–75 percent of the cost isset, even though these costs will not be realized until much later in theproduct life cycle. The environmental costs are analogous to economicones. For example, it is also at the design phase that materials arespecified. This often dictates the production process as well as opera-tion and maintenance procedures (i.e., painting, coating, rust inhibit-ing, cleaning, and lubricating).

As soon as a material is specified as a design decision, the entire lifecycle of that material from acquisition through processing as well as theend of life is now included as a part of the environmental impacts of thedesigned product, process, or system. Therefore, it is at the designphase that the engineer has the greatest ability to affect the environ-

mental impacts associated with the final outcome.As an example, think of all the materials and products that go intoconstruction and furnishing a building. At this point, the engineerneeds to vision the future in regard to how these materials will bemaintained, what cleaning agents will be used, what the water andenergy demands of the building will be, what will happen to the building after its useful life is over, and what the fate of these materialsat the end of the building’s life will be. In terms of transportationsystems, an engineer can think beyond the design of a new highwayintended to relieve urban congestion, because data clearly shows thatthese new transportation corridors will become congested in just a fewyears after the highway is completed.

It is also important to note that it is at the design phase that theengineer has the opportunity to incorporate increased efficiency,

reduced waste of water, materials, and energy, reduce costs, andmost importantly, impart new performance and capabilities. Whilemany of the other attributes listed can be achieved through “end of thepipe” control technologies, it is only by working at the design phase

EPA’s Design for EnvironmentProgramhttp://www.epa.gov/oppt/dfe

Figure 1.11 Percent Costs Incurredversus Design Timeline The costs can

be thought of as economic orenvironmental. During the designphase, approximately 70 percent of thecost becomes fixed for development,manufacture, and use.

Cost committed

Cost incurred

Concept

P e r c e n t c o s t s i n c

u r r e d

20%

40%

60%

80%

100%

Designengineering

Processplanning

ProductionTesting



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that the actual product, process, or system characteristics can bechanged. Choosing a material that is inherently nontoxic has tremen-dous benefits in terms of human health and environmental impacts aswell as eliminating the need to control the circumstances in which thischemical is used and how it is handled. Adding new performance and/or capabilities often brings improved environmental characteristics aswell as offering the opportunity for improved competitiveness and

market share making this a better design for many reasons. Simplycontrolling or minimizing waste through manufacturing or even end of life cannot alter or improve the fundamental nature of the design,which adds value while offering an improved environmental profile.There is even a new recognition that wastewater should be viewed as asource of water, energy, and nutrients, and not just something to beremediated to the minimum standard as cheaply and quickly aspossible. This can have a tremendous impact on the design of nextgeneration wastewater treatment and resource recovery systems.

1.4 Measuring SustainabilityAn indicator , in general, is something that points to an issue or

condition. Its purpose is to show you how well a system is working.If there is a problem, an indicator can help you determine whatdirection to take to address the issue. Indicators are as varied as thetypes of systems they monitor. However, there are certain character-istics that effective indicators have in common (Sustainable Measures,2007) as given in Table 1.3.

Anexample of an indicatoris thegas gauge in your car. The gasgaugeshows you how much gasoline is left in your car. If the gauge shows thatthe tank is almost empty, you know it is time to fill up. Another exampleof anindicator is a midterm report card.It shows a student andinstructorwhether they are doing well enough to go to the next grade or whetherextra helpis needed. Bothof these indicators provide information to helpprevent or solve problems, hopefully before they become too severe.

Another example of a common one-dimensional indicator of economicprogress is gross domestic product (GDP). Note, however, that manyargue that GDP is insufficient to be used as a sustainability indicator, because it measures economic productivity in areas that would not beconsidered in a vision of a more sustainable world (e.g., economics of prisons, pollution control, and cancer treatment).

While the Principles of Green Engineering provide a framework fordesigners, many engaged in sustainability efforts also develop metricsor indicators to monitor their progress in meeting sustainability goals.A sustainability indicator measures the progress toward achieving agoal of sustainability. Sustainability indicators should be a collection of indictors that represent the multidimensional nature of sustainability,considering environmental, social, and economic facets. In terms of campus sustainability indicators, the University Leaders for a Sustain-

able Future (ULSF, 2008) states that “Sustainability implies that thecritical activities of a higher education institution are (at a minimum)ecologically sound, socially just and economically viable, and that theywill continue to be so for future generations.” Table 1.4 provides a

Table / 1.3Characteristicsand Intentionsof Effective Indicators

Relevant

Easy to understand by all stakeholders

Reliable

Quantifiable

Based on accessible data

SOURCE: From the Community Indicators Consortium(www.communityindicators.net).

National TransportationStatistics: Transportation,Energy, Environmenthttp://www.bts.gov

Sustainable Seattlehttp://www.sustainableseattle.org

University Leaders for aSustainable Futurehttp://www.ulsf.org

1.4 Measuring Sustainability 27


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comparison of traditional versus sustainability indicators for a com-munity, and what new information they provide about progresstoward sustainability that is not captured by more traditional indica-tors (Hart, 2007).

Several quantitative sustainability metrics are heavily utilized by

engineers. One of these metrics is the efficiency factor (or E factor),which is a measure of material efficiencies, that is the waste generationfor materials. While efficiencies of all types have always been acomponent of good design, the generation of waste, particularly

Table / 1.4

Traditional Indicators versusSustainability Indicators fora Community andWhat They Say about Sustainability

Economicindicators

Traditional Median incomePer capita income relative to the U.S. average size of the economyas measured by gross national product (GNP) and GDP

Sustainable Number of hours of paid employment at the average wage requiredto support basic needsWages paid in the local economy that are spent in the local economyDollars spent in the local economy that pay for local labor and local naturalresourcesPercent of local economy based on renewable local resources

Emphasis of sustainabilityindicator

What wage can buyDefines basic needs in terms of sustainable consumptionLocal financial resilience

Environmentalindicators

Traditional Ambient levels of pollution in air and waterTons of solid waste generatedCost of fuel

Sustainable Use and generation of toxic materials (both in production and by end user)Vehicle miles traveledPercent of products produced that are durable, repairable, or readilyrecyclable or compostableTotal energy used from all sourcesRatio of renewable energy used at renewable rate to nonrenewable energy


Measuring activities causing pollutionConservative and cyclical use of materialsUse of resources at sustainable rate

Socialindicators

Traditional Number of registered votersSAT and other standardized-test scores

Sustainable Number of voters who vote in electionsNumber of voters who attend town meetings

Number of students trained for jobs that are available in the local economyNumber of students who go to college and come back to the community


Participation in democratic processAbility to participate in the democratic processMatching job skills and training to needs of the local economy

SOURCE: Hart (2007).



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hazardous waste, can be considered a design flaw. As given in Equa-tion 1.1 (and demonstrated in Example 1.4), the E factor measures theefficiency of various chemical industries in terms of the kilograms of material inputs relative to the kilograms of final product (Sheldon,2007). It does not consider chemicals or materials that are not directlyinvolved in the synthesis, such as solvents and rinse water. A highervalue for the E factor means more waste is produced and thus there is a

greater potential for adverse impact on human health and the environ-ment. Manufacturers would thus strive to develop processes where theE factor approaches zero:

E factor ¼

Pkg inputs

Pkg product

(1.1)

e xampl e / 1 . 4 Determining the E FactorCalculate the E factor for the desired product, given the following chemical production process:

CH3CH2CH2CH2OHþ NaBr þH2SO4 ! CH3CH2CH2CH2Br þNaHSO4 þ H2O

Table 1.5 provides details about the molecules involved.

solution

E factor ¼

Pkg inputs

Pkg product

E factor ¼0:0008þ 0:00133þ 0:002

0:00148 ¼ 2:8

In this example, 2.8 times more mass of material inputs are required than are obtained in the finalproduct. This is not close to the value of zero we would want to set as a goal if the company had zerowaste as a sustainability goal.

According to Sheldon, the current bulk chemical industries have E factors of less than 1–5, comparedwith 5 to greater than 50 for fine chemicals, and 25 to more than 100 for pharmaceuticals. This shows

that today there is great opportunity to reduce waste production during chemical manufacturing.Be aware also that this type of calculation is only a measure of mass efficiency and does not consider the

toxicity of the materials used or generated (see Chapter 6 for more information on toxicity and hazard).

Table / 1.5InformationNeededforExample 1.4

Type Molecular Formula Molecular Weight Weight (g) Moles

Reactant CH3CH2CH2CH2OH 74.12 0.8 (added) 0.80 (added)

Reactant NaBr 102.91 1.33 (added) 1.33 (added)

Reactant H2SO4 98.08 2.0 (added) 2.0 (added)

Desired product CH3CH2CH2CH2Br 137.03 1.48 0.011

Auxiliary NaHSO4

Auxiliary H2O

1.4 Measuring Sustainability 29


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1.5 Policies Driving Green Engineeringand Sustainability

There is a close, albeit often unrecognized, link between policy andengineering design. Policies are plans or courses of action, as of agovernment or other organization, intended to influence and deter-mine decisions, actions, and other matters. Governmental policies are

often aimed at protecting the public good in much the same way thatgreen chemistry and green engineering are aimed at protectinghuman health and the environment. Policy can be a powerful driverinfluencing engineering design in terms of which material and energysources are used through subsidies and/or strict regulations onemissions. In this way, policy can play a significant role in supportingengineering design for sustainability. There are two main types of policies that can affect design at this scale: regulations and voluntaryprograms.

1.5.1 REGULATIONS

A regulation is a legal restriction promulgated by government admin-

istrative agencies through rulemaking supported by a threat of sanctionor a fine. While there a traditional environmental regulations focusedon end of pipe releases, there is an emerging policy area focused onsustainable design. Two of the most established examples includeextended product responsibility (EPR) initiatives and banning specificsubstances.

Extended product responsibilities, such as the European Union’s(EU) Waste Electrical and Electronic Equipment directive, hold theoriginal manufacturer responsible for their products throughout thelife cycle. This directive aims to minimize the impact of electrical andelectronic goods on the environment by increasing reuse and recy-cling and reducing the amount of electrical and electronic equipmentgoing to landfills. It seeks to achieve this by making producersresponsible for financing the collection, treatment, and recovery of

waste electrical equipment and by obliging distributors (sellers) toallow consumers to return their waste equipment free of charge. Thisdrives engineers to design electrical and electronic equipment withthe Principles of Green Engineering. For example, these designsconsider end-of-life management and aim for ease of disassembly,recovery of complex components, and minimized material diversity.One positive impact of this approach from a company’s perspective isthat it reconnects the consumer with the manufacturer at the end-of-the-life, life stage.

Another policy approach to driving engineering design towardsustainability goals is banning specific substances of concern. Anexample closely tied to the Electrical and Electronic Equipmentdirective is the EU’s Restriction of Hazardous Substances (RoHS).

RoHS is focused on “the restriction of the use of certain hazardoussubstances in electrical and electronic equipment.” This Directive

Product Policy Institute

http://www.productpolicy.org/content/about-epr

Extended ProducerResponsibility in Californiahttp://www.calrecycle.ca.gov/epr/



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bans the placing on the EU market of new electrical and electronicequipment containing more than agreed levels of lead, cadmium,mercury, hexavalent chromium, polybrominated biphenyl (PBB), andpolybrominated diphenyl ether (PBDE) flame retardants. By banningthese chemicals of concern in significant levels, this directive isdriving the implementation of green chemistry and green engineeringprinciples in terms of designing alternative chemicals and materials

that reduce or eliminate the use and generation of hazardous sub-stances and preventing pollution.

1.5.2 VOLUNTARY PROGRAMS

Another policy strategy for encouraging green engineering design isthrough voluntary programs. Voluntary programs are not mandated

sust design eng innov enveng2nded mihelcic 2013

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