EPA/600/R- 06 / 060 May 2006

LIFE CYCLE ASSESSMENT:

PRINCIPLES AND PRACTICE

by

Scientific Applications Inte rnational Corporation (SAIC) 11251 Roger Bacon Drive Reston, VA 20190

Contract No. 68-C02-067

Work Assignment 3-15

Work Assignment Manager Mary Ann Curran Systems Analysis Branch National Risk Management Research Laboratory Cincinnati, Ohio 45268

NATIONAL RISK MANAGEMENT RESEARCH LABORATORY

OFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268Notice

The U.S. Environm ental Pr otection Agency through i t s Office of Resear ch and Develop m ent funded and managed the resea rch desc ribed here under contr act no. 68-C02-067 to Sc ientific Applications

International Corporation ( S AIC). It has been subj ected to the Agency’ s review and has been approved for publ ication as an EPA docum ent. Mention of tr ade nam e s or commercial products does not constitute

endorsem e nt or reco mmendation for use. Use of th is methodolog y does not im ply EPA appro v al of the conclusions of any specific life cy cle ass ess ment.



### iiForeword

The U.S. Environm ental Pr otection Agency (EPA) is charged by C ongress with protecting the Nation' s land, air, and water re sources. Under a mandate of national environmental law s , the Agency strives to

form ulat e and im plement actions leading to a com p at i b le balance between hu m a n activities and the abilit y of natural s y stem s to suppo rt and nurt u re life. To m e et this mandate, EPA's research program is provi ding data and technical support for solvin g en vironm en tal problems today and b u ildi n g a science k nowledge

base nece ssar y to m a nage our ecological resources wi sel y , understand how pollutants affect our health, and prevent or reduce environm ental risk s in the future

.

The National Risk Management Research Laborator y (NRMRL) is the Agency ' s center for investigation

of technolo g i cal and m a nagem e nt approaches for preventing an d r e ducing risks from pollution that

threaten human health and the environm ent. The focus of the Laboratory ' s resear ch program is on methods and their cost-effectiveness for prevention an d control of pollution to air

, land, water, and

subsurface re sources; protection of water quality in pu blic water sy ste m s; re medi ation of conta m inated sites, sedi m e n ts and ground water; prevention and co ntrol of i ndo o r air polluti on ; and restoration of

ecosy stem s. NRMRL collaborates with both publ ic and pr i v ate sector partners to foster technologies that

reduce the cost of com p lia nce and to anticipa te e m erging problem s. NRMRL ' s re search provides

solutions to environm ental problem s by : developing and prom oting technologies that protect and im prove the environm ent; advancin g scientific and engi neer ing inform ation to supp ort re gulator y an d polic y decisions; and prov idin g t h e technical support and in formation transfer to ensure im plementation of

environm ental regulations and strategies at the national, state, and co mm unity le vels.

This publicati on has been produced as part of the Labo ratory ' s strategic long-term resear ch plan. It is published and made availab l e by EPA's Office of Re s earch and De velopm ent to assist the user

co mm unity a nd to link res earcher s with their clients.

Sally Gutierre z , Dir ector National Risk Management Resear c h Laboratory



### iiiAbstract

The following docum ent provides an int r oductor y ove rview of Life Cy cle Assessment (LCA) and

describes the general uses and m a jor co m ponents of LCA. This document is an update and merger of two previous EP A documents on LCA (“Life Cy cle A sse ss ment: Inventory Guidelines and Principles,”

EPA/600/R-9 2 /245 , and “L CA101” from the LCAcces s , website, http:// www .epa.gov/ORD/NRMRL/lcaccess ). It presents the four basic stages of conductin g an LCA: goal and scop e definition, i nventor y analy s is, im pact a sses s m ent, and im prove m e nt analy s is. The major stages in an LCA study are raw material ac quisition, materials manufacture, production

, use/reuse/ mai n tenance, and waste manag e m e nt. Th e sy stem bounda ries, assu m p ti ons, and conventions to

be addressed in each stage are presented. This docum ent is designed to be an educational tool for

so m e one who wants to learn the basics of LCA, how to conduct an LCA, or how to m a nage someone conducting an LCA. Companies, federal facilities, industr y organi zations, or academ ia can benefit fro m learning how to incorporate environm ental perfor m anc e based on the life cy cle concept into their

decision- m a k i ng processes. This report was sub m itted in fulfillm ent of contract 68-C02-067 by Scientific Applications International Corpora tion ( S AIC) under the sponsorsh ip of the Unit ed States Environm ental Protection Ag ency . T h is report covers a peri od from December 2005 to Ma y 20 06, and wor k was

co m p leted as of May 30, 2 006.



### ivContents



### Notice

......................................................................................................................... ......... ii

Foreword

....................................................................................................................... ..... iii

Abstract

....................................................................................................................... ....... iv

Exhibits

....................................................................................................................... ...... vii

Tables

......................................................................................................................... ....... vii

Abbreviations

.................................................................................................................. . v iii Chapter 1 - Life Cycle Assessm ent ......................................................................................1 What is Life Cycle Assessm ent (LCA)? ..........................................................................1 What Are the Benefits of Conducting an LCA? ..............................................................3

Lim itations of Conducting an LCA .................................................................................5 Chapter 2 - Goal Definition and Scoping ............................................................................7 What is Goal Definition and Scoping? ............................................................................7

How Does Goal Definition and Sc oping Affect the LCA Process? ................................7 Getting Started

................................................................................................................ .7 Define the Goal(s) of the Project .................................................................................7

Determ ine What Type of Infor m ation Is Needed to Inform the Decision-Makers ......8

Determ ine the Required Specificity .............................................................................9

Determ ine How the Data Should Be Organized and the Results Displayed .............11 Define the Scope of the Study ...................................................................................11 Raw Materials Acquisition ....................................................................................11 Manufacturing ........................................................................................................12

Use/Reuse/Maintenance .........................................................................................12 Recycle/W a ste Managem e nt ..................................................................................12

Determ ine the Ground Rules for Perform i ng the W o rk.............................................18 Chapter 3 - Life Cycle Inventory .......................................................................................19 What is a Life Cycle Inventory (LCI)? ..........................................................................19 Why Conduct an LCI? ...................................................................................................19

What Do the Results of the LCI Mean? .........................................................................19 Key Steps of a Life Cycle Inventory..............................................................................19 Step 1: Develop a Flow Diagram ...............................................................................19 Step 2: Develop an LC I Data Collection Plan ...........................................................22 Step 3: Collect Data ...................................................................................................28 Inputs in the Product Life -Cycle Inventory Analysis .............................................29 Outputs of the Product Life -Cycle Inventory Analysis ..........................................34 Step 4: Evaluate and Docum e nt the LCI Results .......................................................44 Chapter 4 - Life Cycle Impact Assessm e nt ........................................................................46 What is a Life Cycle Impact Assessm e nt (LCIA)? ........................................................46 Why Conduct an LCIA ? ................................................................................................46

What Do the Results of an LCIA Mean? .......................................................................47 Key Steps of a Life Cycle Im pact Assessm ent ..............................................................47 Step 1: Select and Defi ne Im pact Categories .............................................................48 Step 2: Classification .................................................................................................48 Step 3: Characterization .............................................................................................50 Step 4: Norm alization ................................................................................................51 Step 5: Grouping ........................................................................................................52

v

### Step 6: W e ighting ......................................................................................................52 Step 7: Evaluate and Docum e nt the LCIA Results ....................................................53 Chapter 5 - Life Cycle Interpretation .................................................................................54 What is Life Cycle Interpretation? .................................................................................54

Com p aring Alternatives Using Life Cycle Interpretation ..............................................54

Can I Select an Alternative Based Only on the Results of the LCA? ............................54 Key Steps to Interpreting the Results of the LCA .........................................................54 Step 1: Identify Significant Issues .............................................................................55 Step 2: Evaluate th e Completeness, Se nsitiv ity, and Consistency of the Data ..........56 Step 3: Draw Conclusions and Recommendations ....................................................58 Reporting the Results .....................................................................................................59

Critical Review ..............................................................................................................59

Conclusion

..................................................................................................................... 60 Appendix A - Sam p le Inventory Spreadsheet ....................................................................63 Appendix B - LCA and LCI Software Tools .....................................................................74 Glossary

....................................................................................................................... ...... 78

viExhibits

P a g e E x h i b i t 1

- 1

. L i f e C y c l e S t a g e s 1

Exhibit 1-2. Phases of an LCA 2

Exhibit 2-1. Sa m p le Life Cy cle Stages for a Treat m e nt Project 13

Exhibit 2-2. Exa m ple Flow Diagra m of a Hy pothetical Bar Soap Sy stem 15

Exhibit 3-1. Generic Unit Process 20

Exhibit 3-2. Detailed Sy stem Flow Diagram for Bar Soap 21

Exhibit 3-3. Allocating Resources and Environm ental Burdens on a Mass Basis f o r a Product a nd

Co-Product 38

Exhibit 4-1. Co mm only U sed Life Cy cle Im pact Categories 49 Exhibit 5-1. Relationship of Interpretati on Steps with other Phases of LCA 55

Exhibit 5-2. Exam ples of Checklist Categori es and Potential Inconsistencies 58

Tables

P a g e Table 3-1. U

. S. National Electrical Grid Fuel Mix f o r 2004 33



### vi iAbbreviations

BOD biolog ical ox ygen dem a nd

Btu British thermal unit

CO carbon m onoxide

COD chem ical ox ygen demand

CO 2 carbon diox id e

DQIs data qualit y i ndicators

EPA United States Enviro nm ental Protection Agency

GWh gigawatt-hou r

ISO International Standards Organization (In ternational Organization of Standardization)

kWh kilowatt-hour

LCA life cy cle ass ess ment

LCI life cy cle inventory

LCIA life cy cle im p act as ses s m ent

LCM life cy cle ma nage m e nt

MJ megajoule

NO 2 nitrogen diox ide

NRMRL National Risk Managem e nt Research Laborator y

REPA Resource and Environm ent a l Profile Analy s is

SETAC Society of Environm ental Toxicology a nd Chem istry

SO 2 sulfur dio x ide

TRACI Tool for the Reduction and Asses s m ent of Chem i cal and other environm ental I m p acts

TRI Toxics Release Inventor y

VOCs volatile organic co m pounds



### vii iChapter 1 Life Cycle A sses sment

What is Life Cycle As ses s m ent (L CA) ?

As environmental awar eness increases, i ndustries and businesses ar e assessing how their activities affect

the environm ent. Society has beco m e c oncerned about the issues of natural resource depletion and

environm ental degradation. Many busi n esses have responded t o this awar eness by providi ng “greener” products and using “greener” processes. The envi ronmental perfor m ance of products and processes has

beco m e a key issue, which is why som e co m p anies ar e investigating way s to m i nim i ze their effects on the

environm ent. Many com p anies have fou nd it advanta g eous to expl ore way s of m oving beyond

co m p liance using poll u tio n prevention st rategies and environm ental management sy stems to improve their environmental perfor m ance. One such tool is LCA. This concept considers the entire life cy cle of a product (Curr a n 1996)

.

Life cy cle assessment is a “cradle- to-grave” approach for assessing industr ial s y stem s. “Cr a dle-to-grave” begins with t h e gathering of raw m a terials fro m the ea rth to create the prod uct and ends at the point when

all m a terials are returned to the earth. L C A evaluates all stages of a product ’ s li fe fro m the perspective

that the y are interdependent, meaning that one operati on leads to the next. LCA enables the es timation of

the cum u lativ e environm en tal im pacts resulting from a ll stages in the product lif e cy cle, often includin g i m pacts not c onsidered in m o r e traditional analy ses (e.g ., raw m a t e rial extractio n, m a t e rial tra n sportation,

ultim ate product disposal, etc.). By i n cluding th e im pacts throughout the product life cy cle, L C A provides a com p r e hensive view of the environm en tal aspects of the product or pr ocess and a more accurate pictu r e of the true environm ental trade-offs in product and process sel ect ion.

The term “life cy cle” refers to the m a jor activiti es in the course of the product ’ s l i fe-span fro m its manufacture, use, and maintenance, to its final dis posal, includi ng t h e raw m a terial acquisition required to manufacture the product. Exhibit 1-1 il lustrates the possi ble life cycle stages that can be considered in an LCA and the typical inputs / outpu ts measured.

E x h i b i t 1- 1. L i f e C y c l e S t age s ( S ou r c e : E P A

, 1 993 ) Recycle / W aste M anagement

U se / Reuse / M aintenance M anufacturing Raw M aterials Acquisition

System Boundary Inputs Ou tp uts

Raw

M aterials

Energy A tm os pheric

Em is sions

Waterborne

Wastes

Solid

Wastes

Coproducts

O ther

Releases



### 1Specifically

, LCA is a tech nique to assess the enviro nmental aspe c t s and potentia l im pa cts a s s o ciated with a produc t, process, or service, by :

• Co m p iling an inventor y of relevant energ y a nd m a terial inputs and environm ental releases

• Evaluating the potential environm ental i m p acts a ssoci ated with identified inputs and release s

• Interpreting t h e results to help decision- makers make a m o re informed decision.

The LCA process i s a sy stematic, phased approach and consists of four com pone nts: goal defi nition and scoping, inventor y anal y s is , im pact assessm ent, and interpretation as illustrated in Exhi bit 1- 2:

1. Goal Definition a nd Sco p i n g - Define and describe the product, pr ocess or activ ity.

Establish the context in which the asses s m ent is to be made and identify the boundaries

and environm ental effect s to be reviewe d for the assess ment.

2. Inventory Analysis - Identify and quantify energy, water and materi als usage and

environm enta l releas es (e.g ., air e m issio n s, solid waste disposal, waste w a ter dis c harges).

3. Impact Asses sment - Ass e s s the potential hum an and ecological eff ects of energ y , water,
and m a t e rial usage and the environm ental re lea ses id entified in the inventory analy s is.

4. Interpretation - Evaluate the results of the inventory analy s is and im p act as se ss ment to select the preferred produc t, process or service with a clear understanding of the uncertainty and the assumptions u sed to generate the results.

Life Cycle A ssessm en t Fram ew or k

Goal
D efinitio n an d Scope

In ven tory A na ly sis

Impact
A ssessment In terpretation

E x h i b i t 1- 2 . P h a s e s o f a n L C A ( S o u r c e : I S O

, 19 9 7 )



### 2Life cy cle ass ess ment is unique because it encom p a s s es all process es and environmental relea ses beginnin g wit h the extraction of raw m a terials and the productio n of energy used t o create the product throug h the u se and final disposition of t h e product. When decidin g between two or m o re alternatives,

LCA can hel p decision-makers co m p ar e all m a jor en vironm ental i m p acts c a use d by products, processes,

or services.

What Are th e Benefits of Conducting an LCA?

An LCA can help decision- m akers sele c t the product or process that results in the least i m p act to the

environm ent. This inform ation can be us ed with othe r factors, such as cost and performance dat a to select a product or process. LCA data identifies the transfer of environm ental im pacts f r om one media to another (e.g., eli m inating air e m issions b y creating a waste w ate r ef fluent instead) and/or from one life

cy cle stage to another (e.g., from use and reuse of th e product t o the raw m a t e rial acquisition phase). If an LCA were not performed, the transfer m i ght n o t be recognized and properl y i n cluded in t h e analy s is

because it is outside of the t y pical scope or focus of product selection processes.

LCA Helps to Avoid Shif t ing Environ m ental Problem s from One Place to Another

An LCA allows a decision maker to stud y an entire p r oduct s y stem hence avoidi ng the suboptim ization that could result if only a single process were the focu s of the study. For exam pl e, when selecting between two rival products, it may appear that Option 1 i s better for the environm en t because it ge nerates le ss s o lid waste than Option 2. However, aft e r perfor m ing an LCA it m i ght be

deter m ined that the first option actually creates l a rger cradle-to-gra v e environm e n tal im pa cts when

mea s ured acr oss all three media (air, w a ter, land) (e.g., it m a y cause m o re che m ical e m i ssions during

the manufact uring stage). Therefore, the second prod uct (that produces solid waste) m a y be viewed as producing less cr adle-to-grave environmental har m or im pact than the first technology because of

its lower chemical emissions.

This abilit y t o track and document shifts in e nvironm ental i m pacts can help decision m a kers and managers full y characteriz e the environm ental trade-o ffs associ ated with product or process alternatives. By perform in g an LCA, analy s ts can:

• Develop a syste m atic eval uation of the envir onm enta l consequences as sociated with a given product.

• Analy ze the environm ental trade-offs ass ociated with one or m o re s p ecific products/process es to help gain stakeholder (state, co mm uni ty, etc.) accep tance for a planned action.

• Quantify environm ental rel ease s to air, water, and la nd in relation to each life c y cle stage

and/or m a jor contributing process.

• Assist in identify i ng signifi cant shifts in e nvironm enta l im pa cts bet w een life cy cle stages and

environm ental media.

• Asse ss the human and ecological effects of m a t e ri al consum ption and envir onm ental releases to

the local co mm unity , region, and world.

• Co m p are the health and ecological im pa cts betw e e n two or m o re ri val products/processe s or identify the im p acts of a s p ecific product or process.

• Identify im pa cts to one or m o r e specifi c environm ental area s of concern.



### 3

### 4 A Brief History of Life-Cycle Assessment

Life Cy cle Assessment (LCA) had its beginnings i n t h e 1960 ’s. Concerns over the lim itation s of raw

materi als and energy resources sparked i n terest in finding way s t o c u m u latively account for energy use and to project future resource supplies and use. In one of the f i rst publicatio ns of its kin d

, Harold

S m ith reported his calculation of cum u lative ener gy requirements for the prod uction of chem ical

interm ediates and pro ducts at the World Energ y Confe r ence in 1963

.

Later in the 1 960 ’s, gl obal m odeling studies publishe d in The Limi ts to Growth (Meadows et al 19 72)

and A Blueprint for Survival (Goldsm ith et al 197 2) resulted in pred ictions of the effects of the

world’ s changing populations on the de mand for fini te raw materia l s and energy resources. T h e predictions for rapid depletion of fossil fuels a nd cli m atological changes resulting from excess waste
heat sti m ulate d m o re detail ed calculations of ener gy us e and output in industrial process es. During this period, a bout a d o zen studies were performed to estimate costs and enviro n m ental im plications of

alternative sources of ener gy

.

In 1969, researchers initiat e d an internal study fo r The Coca-Cola Co m p any th at laid the foundation

for the current methods of l i fe cy cle inve ntor y anal y s is in the United States. In a co m p arison of different beverage containers to deter m ine which container had the lowest rele ase s to the

environm ent and least affected the suppl y of natura l r esources, this study quantif ied the raw materials

and fuels used and the environm ental lo adings from t h e manufactu r ing processes for each container.

Other co m p a n ies in both the United States and Eu rope perfor m ed s i m ilar co m p a r ative life cy cle inventory analy ses in the e a rly 1970’ s

. At that tim e, many of the available sources wer e derived from publicl y -avail able sources such as government documents or technical papers, as specific industrial

data were not available.

The process of quantif y i ng the resource use and e nvir onm ental rel e ases of products became k nown as a Resource a nd Environm ental Profile Analy s is (REPA), as practi ced in the United States. In Europe,

it was called an Ecobalance. With the f o rmation of p ublic interest groups encou r aging in dustr y to
ensure the ac curacy of informa tion in t h e public domain, and with the oil short a ges in the early

1970 ’s, ap pro x imately 15 REPAs were performed between 1970 a nd 1 975. Thr ough this peri od, a protocol or standard resear ch methodology for conduc ting these studies was developed. T h is m u ltistep m e thodology i nvol ves a num ber of assu m p tions. During these y ears, the assum ptions and techniques used underwent considerable review by EP A and major industr y repre sentatives, with the

result that reasonable methodolo g ies were evolved.

From 1975 through the early 1980’ s , as interest in these co m p rehensive studies waned because of the fading infl uence of the oil crisis, environmenta l concerns shifted to issues of hazardous and

household waste m a nag e ment. However, throu gho ut this time, life cy cle invent o r y anal y s is

continued t o be conducted and the m e th odolo g y im pr oved thr oug h a slow stream of about two studies

per y ear, m o st of which foc u sed on energ y requireme nts. During this ti m e , European interest grew

with the establishment of an Environm e n t Direct orate (DG X1) by the European Co mm is sion. European LCA practitioners developed approaches para llel to those being used in the USA. Besides working t o standardize pollution reg u lations thro ugh o u t Euro pe, DG X1 issued the Liquid Fo od

Container Directive in 198 5, which charged m e mber co m p anies wi th m onitoring the energy and raw

materials consu m ption and solid waste generation of l i quid f ood co ntainers.When solid w aste bec a m e a worldwide issue in 198 8, LCA again e m erged as a t ool for analy z ing

environm enta l problem s. As interest in all area s affe c ting resources and the environm ent grows, the methodology for LCA is again being im proved. A broad base of consultants and researchers across the globe has been further refining and e xpandin g the methodolog y. The need to m ove bey ond the

inventor y to i m p act assessment has brought LCA m e thodol ogy to another poi nt of evoluti on ( SETAC 1991; SETAC 1993; SET AC 1997).

In 199 1, conc erns over the inappropriate use of LCAs to m a ke broad m a rketing claim s made b y product m a nufacturers resulted in a statement issued by eleven State Attorney s General in the USA denouncing t h e use of LCA results to prom ote pr oducts until unif o rm m e thods for conducti ng such

asse ss ments a r e developed and a consensus reached on how this type of environmental co m p arison can be advertised non-deceptivel y

. T h is acti on, along with pressure from other environm ental organizations to standardize LCA methodolog y, led t o the develop m ent of the LCA standards in the

International Standards Organization (I SO) 14000 series (1997 thr ough 20 02).

In 2002, the United Nations Environm e n t Programme (UNEP) joined forces wi th the Society of

Environm ental Toxicology and Chem i s try (SETAC) t o launch the Life Cy cle Initiative, an

international partnership. The three program s of the Initiative aim at putting life cy cle thinking into practice and at im proving t h e supporti ng tools thro ug h better data and in dicators. The Life Cy c l e Managem e nt (LCM) progr am creates awareness and im proves skills of decision-makers by producin g inform ation materi als, est ablishing for u ms for sh aring best practice, and carry in g out train i ng

program s in a ll parts of the world. The Life Cy cle Inve ntory (LCI) program i m pro v es global access to transparent, high qualit y lif e cy cle data by hosting and facilitating expert groups whose work results

in web-based inform ation s y stem s. The Life Cy cl e Im p act As se ss ment (LCIA) program incr ease s the qualit y and gl obal reach of life cy cle indi cators by prom oting the exchange of vie w s am ong experts
whose work results in a set of widely accepted reco mmendations.

Limitations of Conducting an LCA

Perfor m ing an LCA can be resource and time intensiv e. Depending upo n how t h oroug h an LC A the user wishes to conduct, gathering the data can be problem at ic, and the availability of data can greatly im pact the accuracy of the final results. Therefore, it is im portant to weigh the availability of data, the time

necessary to conduct the st udy

, and the f i nancial res ources required against the projected benefits of the

LCA.

LCA will not deter m ine which product or process is the m o st cost effective or works the best. Therefore,

the inform ation develo ped in an LCA stud y sh ould b e used as one co m ponent of a m o re co m p rehensive decision process a sse ssing the trade-offs with cost and performance, e.g., Life Cycle Manage ment.

Life Cycle M a nagement

Life Cy cle Manage m e nt (L CM) is the application of life cy cle thinking to m odern business practice,

with the aim t o m a nag e the total life cy cle of an organization’ s product and services toward m o re sustainable consum ption and pro ductio n (Jensen a nd Remmen 2004). It is an in tegrated framework of concepts and techniques to address environm enta l, econom i c , technological, and social aspects of products, services, and organizations. LCM, as an y other management pattern, is applied on a voluntary basis and can be adapted to the speci fic nee d s and charac teristics of individual

or g anizations ( SETAC 2004 )

.



### 5There are a n u m b er of way s to conduct Life Cy cle Im p act Assessment. While the methods are ty p i cally scientifically -based, the com p l e xity of environm ental sy stems has l e d to the deve lopm ent of al ternative

im pact m odels. Chapter 4 expands on thi s

.



### As m e ntioned earlier, an LCA can help identify potential environm ental tradeoffs. However, converting the im pact results to a single score re quires the use of value judgm e nts, which m u st be applied by the comm i ssioner of the study or the m odeler. This can be done in different ways such as through the use of an expe rt panel, but it cannot be done based solely on natural science.

6Chapter 2 Goal Definition and Scopi n g

What is Goal Definition a nd Scoping? Goal definition and scoping is the phase of the LC A process that defines the purpose and method of including life cy cle environmental i m pa cts into the de cision- m a king process. In this phase, the following

item s m u st be determ ined: the t y pe of i n formation that is needed to add value to the decision-making process, how accurate the r esults m u st be to add va lue

, and how t h e results should be interpret e d and display e d in order to be meaningful and usable.

How Does Goal Definitio n and Scopin g Affect the LCA Process? The LCA process can be used to deter m ine the poten tial environm e n tal im pa cts f r om any product, process, or service. The goal definition a nd scopi ng of the LCA project will deter m ine the ti m e and resources needed. The defined goal and scope will guide the entire process to ensure that the m o st meaningful results are obtained. Ever y decision m a de throughout the goal definiti on and scopi ng phase

im pacts either how the study will be conducted, or the relevance o f the final results. The foll owing

section identifies the decisi ons that m u st be made at the beginni ng of the LCA stud y and the i m p act of

these decisio n s on the LCA process.

Getting Started The following six basic decisions shoul d be m a de at the beginni ng of the LCA process to m a k e effective

use of time a nd resources:

1. Define the G o al(s) of the Project

2. Determine What T y pe of I n form ation Is Needed to Inform the D eci sion-Makers

3. Determine the Required Specificity

4. Determine How the Data Should Be Or ganized and t h e Results Display e d

5. Define the Scope of the St u d y 6. Determine the Ground Rul es for Performing the Wor k

Each decision and its associated i m pact o n the LC A process ar e explained below in further detail.

Define the Goal(s) of the Project

LCA is a versatile tool for quantif y i ng t h e overa ll (cradle-to-grave) environm en tal i m pacts from a product, proc ess, or service. The prim ary goal is to c hoose the best product, process, or servi ce with the

least eff ect on hum an heal th and the environm en t. Conducting an LCA also can help gui de the developm ent of new products, processes, or activities toward a net reduction of re source requirem e nts and

em issions. There m a y also be secondary goals for per f orm i ng an LCA, which would var y dep e nding on the t y pe of project. The fo llowing are exam ples of po ssible applications for life-cy cle inventories, m o st of which require so m e level of im pact assessment in addition to the inventory:

• Support broad environmental assessments - The results of an LCA are valuable in understanding the

relative environm ental burdens resulting from evolu tionar y change s in given processes, products, or packaging ov er tim e ; in understanding t h e relativ e environm ental burdens between alternative processes or materi als used to m a ke, distribute, or us e the same product; and i n co m p aring the

environm enta l aspects of al ternative products that serve the sa me us e.

• Establish bas eline information for a process - A key application of an LCA is to establish a baseline

of inform ation on an entire sy stem given current or predicted practices in the m a nufacture, use, and disposal of the product or c a tegory of pr oducts. In some cases, it may suffi ce to establish a baseline for certain processes associated with a product or p ackage. This baseline would consist of the energy



### 7and resource requirem e nts and the envir onm ental lo adings from the product or process sy stems that are analy zed. The baseline inform ation is valuab le for initiating im provem e nt an aly s is by appl y i ng specific chan ges to the baseline sy stem

.

• Rank the relative contribution of individual steps or process es - Th e LCA results provi de detailed data regarding the individual contributions of each st e p in the s y ste m studied to the total sy ste m

. The data can provide direction to efforts for change by showing which steps require the m o st e n ergy or other resources, or whic h steps contribute the m o st pollutants. This application is especiall y relevant for internal indust r y st udies to s upport decisions on pollu ti on preventi on , resource conservation, and waste m i nim i zation op portunit i es.

• Identify data gaps - The pe rformance of an LCA for a particular sy ste m reve als a r eas in which data for particular processe s are lacking or are of uncer tain or questionable qualit y

. Inventory followed by im pact a s s ess ment aids in identify i ng areas where data augmentation is appropriate for both
stages.

• Supp ort pu bli c policy - For the publ ic po licy m aker, LCA can help broaden the r a nge of

environm ental issues consi d ered in deve loping regulat ions or setting policies.

• Support product certificati on - Pro duct certifications have tended t o focus on relatively few criteria. LCA, only w h en applied using appropriate i m pact as sess ment, can provide information on the

indivi dual, si m u ltan e ous effects of m a n y prod uct attributes.

• Provide information and direction to decision-makers

- LCA can be used to inf o r m industry

, governm e nt, and consum er s on the tradeoffs of alte rnative processes, products, and m a t e rials. The data can give industr y direction in decisions regarding producti on materi als and processes and create a better informed public regarding envir onm ental is sues and consumer choice s.

• Guide produc t and process development - LCA can help gui de manufacturers in the developm ent of new products, processes, and activities toward a net reduction of re source requirem e nts and

em issions.

Dete rmin e What Type of Information Is Need ed to Inform the Deci sion-Makers LCA can help answer a num b e r of im portant questio ns. Identify i ng the questions that the decisionmakers care about will help define the st udy param e ters. Som e exam ples include:

• What is the im p act to particular interest ed parties and stakeholders?

• Which product or process causes the le a s t environm e n tal im pa ct (quantifiably ) overall or in each stage of its life cy cle?

• How will changes to the current product/ process a ffect the environm ental i m pacts across all life

cy cle stages?

• Which technology or proce ss causes the least am ount of acid rain, sm og for m atio n, or dam a ge to local trees (or any other im pact category of concern)?

• How can the process be ch anged to reduce a spe c if ic environm enta l im pa ct of concern (e.g., global

warm ing)?

Once the appropriate questions are identified, it is impor tant to determ ine the types of information needed to answer the questions.



### 8Attributional LCA versu s Consequen t ial LCA

During a workshop held in 200 3, specifically o n life cy cle in ventor y for electricity generation, participants recognized the need to choo se an allocation m e thod depending consi d erably upo n whether the life cy cle asse s s m ent is being perform ed f r om an attributional or a c onsequential point of

view. The term “attributional life cy cle asse ss ment” was defined a s an atte m p t t o answer “how are things (i.e. pollutants, resources, and excha nges a m o ng processes) flowing within the chosen

tem poral window?” while “consequential life cy cle asse ssment” at tem p ts to answer “how wil l flows beyond the i mmediate sy stem change in response to decisions?” For exam ple, an attribution a l LCA

would exam i n e the consequences of using green power co m p ared t o conventi o nal sources. A consequential LCA would consider th e consequences of this choice in that only a certain a m ou nt of

green power may be available to customers, cau sing s o me custo m e r s to buy conventional ene r gy once the supply of greener sources was gone. The choice between conducting an attributional or a

conse q uential asse ss ment de p ends on the stated g oal of the stud y ( C u rran
, Mann

, & Norris 2005 )

.

Dete rmin e the Requir e d Specificity At the outset of every study, the level of specificity must be decided. In som e cases, this level will be obvious from the application or i n tende d use of the i n fo rm ation. In other instances, there may be several options t o ch oose from

, ranging from a co m p letely g e neric study t o one that is product-specific in every

detail. Most studies fall somewher e in between.

An LCA can be envisioned as a set of linked activiti es that describe the creation, use, and ultimate disposal of th e product or material of interest. At each life cy cle st age, the analyst should beg i n b y answering a series of questions: Is the pr oduct or s y ste m in the life cy cle stage specific to one com p any or manufacturing operation ? Or does the product or s y st em represent co mm on prod ucts or sy ste m s generally

found in the marketplace and pro duced or used b y a num ber of com p anies?

Such questions help determine wh ether data collected for the i nventor y sh ould be specific to one

co m p any or manufacturing facility

, or whether the data should be m o r e general to represent common industrial pra c tices.

The appropriate response t o these questions often rest s on whether the life cy cle is being perfor m ed for internal organizational use or for a m o re public purpos e. Accessibil ity to product- or facility -s pecific data

may also be a factor. A com p any m a y be m o re intere sted in exa m i n ing its own form ulation and asse m b ly operations, whereas an industry group or governm e nt ag ency m a y be m o r e interested in characterizing

industr y

- wide practice. LCAs can have a m i x of produ ct-specific and ind u str y -av e rage inform ation. F o r

exa m ple, a c e r eal manufact urer perform i ng an analy s is of using recy cled paperboard for its cereal boxes might appl y t h e following logic. For op erations c onducted b y the manufacturer, such as box printing

, set up, and filling, data specific to the product would be obtained because average da ta for printing and filling

across the cereal industr y o r for ind u str y in general would n o t be as useful.

Stepping back one stage to package m a n u facturing, the cere a l m a nu facturer is ag ain faced wit h the specificity de cision. The d a ta could be p r oduct-sp ecific, or generic data for the manufacturing stage could be used. The produc t-specific app r oach has these advantages : the aggregated data reflec t the operations of the specific paper m ills su pply i ng the re cy cled board, and the energy and resources

associat ed wi th this stage can be co m p ar ed with those of sim i l a r specif icity for the filling, packaging, and

distribution st age. A li m itation of t h is option is t h e additional cost and tim e associated with collecting



### 9product-specific data fro m the m ills and the level of cooperation t h at needs to be established with the
upstream ven dors. Long-t er m confidentiality agr eements with vendors may also represent unacceptable burdens compared with the value added by the m o re specific data.

Dete rmin e the Data Requirements

The required level of data accura cy for the proj ect depends on the use of the final results and

the intended audience (i.e. will the results be u sed to support decision-m a king in an internal process or in a public forum ? ). For exam pl e, if the intent is to use the results in a public

forum to support product/ process sel ect ion to a l o cal co mm unity or regulator, then esti m at ed data or best engineering judgm ent for the primary m a terial, energy , and waste str e a m s m a y not be sufficiently accurate to justify the final conclusions. In contrast, if the intent of perform ing the LCA is for internal decision-m a king purposes only

, then esti m ate s and best engineering j udgm ent m a y be applied more freque ntly. This m a y r e duce the overall cost and time required to perform the LCA, as w e ll as enab le c o m p letion of the study in the absence of precise, first-hand data.

In addition to the intended audience, the requi red level of data accuracy could be based on the criticality of the decision to be m a de and the am ou nt of m oney i nvolved in t h e decision.

The alternative decision path, using industrial average data for making recy cled p a perboard, has a parallel mix of advantages and li m i tations. Use of average, or generic, data may be adva ntageous for a manufacturer considering u se of recy cled board for wh ich no current vendors have been identifi e d. If the quality of these average da ta can be dete r m ined and is acceptable, t h eir use m a y be preferable. The

lim it ation is that data from this stage m a y be less co mparable to that of m o re product-specific stages.
This lim itatio n is especiall y im portant in studies that mix product-s p ecific and more general analy ses in

the sa m e lif e- cy cle stage. For exam ple, co m p aring vi rgin and rec y cled paperboard using prod uct-specific

data for one material and generic data for the other c ould be probl em atic.

Another lim itation is that t h e generic data m a y mask technologies t h at are m o re environm entally

burdensom e. Even with some measur e of data variab ility, a decision to use a particular m a terial made on the basis of g e neric data may m i srepresent true load in gs of the actual suppliers. Opportunit i es to identif y specific facilities operating in a m o re en vironm entall y sound m a n n er are lost. Generic data do not necessarily represent indust r y

- wide pract ices. The ex tent of representation depends on the qual ity and coverage of the available data and is i m possible to state as a general rule.

It is reco mme nded that the level of specificity be ve ry clearly defined and comm u n icated so that readers

are m o re able to understand the differences in the final results. Bef o re initiating data collection and periodically t h roug hout the stud y , t h e analy s t sho u ld r e visit the specificity decision to determ ine if the approach sele c ted for each stage re mains valid in view of the intended use.

Foreground and Background Data

An im portant elem ent in LCA practice is the distin ction that has be en made between foregroun d and backgroun d d a ta. The foregroun d s y stem refers to the sy stem of prim ary concern. The backg r ound

sy stem delive r s energy and material s to the fore ground sy stem as a ggregated data sets in whic h

indivi dual pla n ts and opera tions are not i d entified. Th e selection of foregroun d or backgroun d data

decides if eit h er m a rginal or average data are to be used.



### 10Dete rmin e How the Data Should Be Organiz ed an d the Results Displayed LCA practitioners define how data s houl d be organize d in term s of a functional u n it that appropriately

describes the function of the product or process being st udied. Careful selection of the functional unit t o

mea s ure and display the LCA results wi ll im prove th e accura cy of the study an d the usefulness of the

results.

When an LCA is used to com p are two or m o re produ cts, the basis of com p arison shoul d be e quivalent use, i.e., each sy stem should be defined s o that an equa l am ount of product or equivalent service is

delivered to the consumer. In the handw ashing exam p l e, if bar soap were co m p ar ed to liquid s o ap, the logical basis for com p arison would be an equal num be r of handwashings. Anot he r exam ple of equivalent

use would be in com p aring cloth diapers to disposable diapers. One type of diaper may ty pically be changed m o re frequently t h an the other, and m a rke t/u se studies show that often cloth diapers are doubled, whereas disposables are n o t. Thus, thr oughout a da y, m o re cloth diapers will be used. In thi s case, a logical basis for com p ari s on between the sy stem s woul d be the total num ber of diapers used over a set period of tim e.

Equivalent us e for com p a r a tive studies can often be based on volume or weight, particularly when the

stud y com p ares packaging for deliver y o f a specific pr oduct. A bev e rage container study m i ght consider 1,000 liters of beverage as an equi valent use basis for co m p arison, because the product m a y be delivered

to the consu m er in a variety of different -size c ontaine rs having different life-cy cle charact eristi cs.

An Example of Selecting a Functional Unit

An LCA study com p aring two t y pes of wall insulation to determ in e environm en tal preferability m u st
be evaluated on the same f unction, the ability to d ecrease heat flow. Six square feet of four-inch thick insulation Type A is not necessaril y the sa m e a s six square feet of four-inc h thick insulation Type B. Insulation ty pe A may have an R factor equal to ten, whereas insulation ty pe B m a y have an R factor equal to 20 . Ther efore, type A and B do not provide t h e sam e am ount of insulation and

cannot be com p ared on an equal basis. If Type A decreases heat fl ow by 80 per cent, you m u st
determ ine how thick T y pe B m u st be to al so decrea se heat flow by 80 percent.

Define the S c ope of the Study As Chapter 1 explained, an LCA includes all four st ages of a product or process life cy cle: raw materi al acquisition, manufacturing, use/reuse/maintenance, and recy cle/waste management. These product stages are explained in m o re detail below. To d e term ine whether one or all of the stages should be included in the scope of the LCA, the following m u st be asses sed: the goal of the study

, the required accuracy of the results, and the available ti me and resources. Exhib it 2-1 provides an exa m ple of life cy cle stages that

could be incl uded in a proj ect re lated to treatment technolo g ies.

Raw Materials Acquisition The life cy cle of a product begins with the re m oval of raw m a t e rial s and energy sources fro m the earth. For instance, the harvesting of trees or t h e m i ning of nonrenewable m a terials would be considered raw

materi als acq uisition. Transportation of these m a t e ri al s fro m the point of acquisition to the point of processing is also included in this stage.



### 11Manufacturing During the manufacturing stage, raw materials are tran sformed into a product or package. The product or package is then delivered to the consumer. The manufacturing stage consists of three steps: materials manufacture, product fabri cation, and fil ling/packagin g/distributi o n

.

Materials Ma nufacture - T h e materials manufacture step invol ves the activities that convert r a w materials into a form that can be u sed to fabricate a fin i shed product

.

Product Fabr ication - The product fabri cation step takes the m a nufactured m a t e rial and processes it into a product that is ready to be filled or packaged.

Filling/Packaging/Distribution - This step finalizes the products and prepares them for ship ment. It includes all of the manufacturing and transportation a c tivities that are necessary to fill, package, and distribute a finished prod u c t. Products are transpor ted either to ret a il outlets or directly t o the consumer. This stage acco unts for the e nvironm enta l effects cause d by the m ode of transportation, such as trucking and shi ppi ng.

Use/R e use/M a intenance This stage involves the co nsumer’s actual use, reuse, and m a intenance of the pro duct. Once the product is

distributed to the consum er , all activities associat ed with the useful life of the product are included in this stage. This includes energy dem a nds an d envi ro nm en tal wastes from both produ ct storage and

consum ption. The product or m a t e rial may need to be reconditioned, repaired or serviced so that it will maintain its perform ance. When the consu m er no lo nger needs the product, t h e product will be recy cled or disposed.

Recy cle/Wast e Manage me nt The recy cle/waste manag e m e nt stage i n cludes the energ y require ments and environm ental wastes
associat ed wi th disposition of the produc t or m a t e rial.



### 12Each step in the life cy cle of a product, package, or materi al can be categoriz ed within o n e and onl y one of these life-c y cle stages. Each step or process can b e viewed as a subsy s tem of the total product sy stem

. Viewing the steps as subsystems facilitat es data gatheri ng for t h e inventor y of the sy stem as a whole. The

boun daries of subsy s tem s are defined b y life-cy cle stage categories in Chapter 3. The rest of this chapter deals with defining bou nda ries of the whole prod uct sy stem . Many decisions m u st be m a de in defining the specific boundaries of each sy stem

.

Product s y stems ar e easi er to define if the sequence of operations associated with a product or materi al is

broken down into prim ary and secondary categories. The prim ary
, or zero-order, sequence of activities directly contr i butes to m a k i ng, using, or disposi ng of t h e product or materi al. The secondary categor y includes auxiliary m a terial s or processes that contribute to making or doing som e t h ing that in turn is in the prim ary activity sequence. Several ti ers of a uxiliary m a t e rials or processes may extend further and



### 13further from the main sequence. In setting s y stem bo undaries, the analy s t m u st decide where the analy s is

will be lim it ed and be ver y clear about the reasons fo r the decision. The followi ng questions are useful in setting and de scribing specific sy stem bo undaries:

• Does the anal ysis need to cover th e entire life cycl e of the product? A theoreticall y com p lete lifecy cle sy stem would start with all raw m a terials and energy sources in the earth and end with all

materi als bac k in the earth or at least somewher e in the environm e n t but not part of the s y stem . Any

sy stem boundary different f r om this repr esents a d eci sion by the analy s t to lim it it in som e way. Understanding the possible consequences of such d ecisions is im po rtant for evaluating tradeoffs

between the abilit y of the r esulting inve ntor y t o thoroughl y address environm ental attributes of the product const r aints on cost, time, or other factors th at may argue in favor of a m o re lim ited boundar y

. Too lim ited a bou ndar y m a y exclude co nsequential act ivities or elements.

Depending on the goal of t h e study

, it is possible to e x clude certai n stages or activities and still

address the is sues for whic h the life-cy cle ass ess ment is being perfor m ed. For exa m ple, it m a y be possible to ex clude the acquisition of raw m a terials without affecting the result s. Supp ose a co m p any wishes to perform an LCA to evaluate alterna tive dr y i ng s y stems for form ulating a snack food product. If the technologie s are indifferent to t h e f eedstock, it is possible to assu me the raw materials acquisition stage will be identical for all options. If the decision will be based on selecting a dry i ng

sy stem with l o wer energy use or environmenta l burdens, it may be acceptable to analy ze such a

lim ited sy stem . Ho wever, with this s y stem boundar y , the degree of absolute diff erences in the overall

sy stem energy or envir o n m ental im pact cannot be de term ined. The difference in the pro duct manufacturing stage m a y represent a m i nor com ponent of the t o tal sy stem . Therefore, statements

about the to tal sy stem cannot be m a de.

• What will be the basis of use for the product or material? Is the st ud y i n tended to com p are different product s y ste m s? If the pr oducts or pr ocesses ar e us ed at different rates, packag ed in var y ing quantities, or co m e in different sizes, how can one accurately compare them ? Can equivalent use ratios be developed? Sho u l d m a rket shares be c onsidered to estim ate proporti onate burden for m each product i n a g i ven category? Is the stud y inte nded to com p are service sy stem s? Are the service functions clearly defined so that the inp u t and out puts a r e properl y pr oportio ned?

• What ancillar y materials or chemicals a re used to make or package the product s or run the

processe s? Might these ancillary m a ter i als or chem i cals contribute m o re than a m i nor fractio n of the

energy or em i ssions of the sy stem to be analy zed? How do the y c o m p ar e by w e ight with other

materi als and che m ic als in the product sy stem s?

• In a comparative analysis, are any extra products re quired to all o w one produc t to deliver equivalent or similar performance to a nother? Are any extra mat e rials or servi ces required f o r one service to be

functionall y e quivalent to anothe r or t o a com p arable product ?

Exhibit 2-2 s hows an exam pl e of setting sy stem boundaries for a product basel ine analy s is f o r a hy pothetical bar soap sy ste m . Tallow i s the m a jor ra w m a te rial for soap production, and its pri m ary raw material source is the grain fed to cattle. Production of paper for pa ckaging soap is also included. The

fate of both t h e soap and it s packaging end the life c y cle of this sy s t em . Minor i nputs coul d i n clude, for

exa m ple, the energy required to fabricate the tires on the com b ine used to plant and harvest the grain.



### 14Exhibit 2-2. Example Flow Diagram of a Hypothetical Bar Soap System

In an LCA to create a basel ine for future product developm ent or i m provem e nt, the unit upon w h ich the analy s is is performed can be al m o st anything that pr oduces internally consistent data. In the bar soap

exam ple, one possible usage unit could b e a single ba r. However, if the product packaging were being analy zed at the sa me ti me, it would be im portant fo r co nsistency to c onsider packaging i n differ e nt

am ounts such as single bars, three-packs, and so o n

.

If the LCA were intended to anal y ze whether bar soap shoul d be manufactured using an ani m al-derived or vegetable-derived raw m a terial source, the sy stem boundaries and units of anal ysis would be m o re

co m p licated. First, the sy s t e m flow diagra m woul d have to be expa nded to i n clu d e the growin g, harvesting, and processing steps for the alternative fe edstock. Then the performance of the finished product wou l d have to be considered. Do the opt ions result in a bar that gets used up at different rates

when one m a terial or the other is chosen? If this we re the case, a st rict co m p aris on of equal-weight bars

would n o t be appropriate.

Suppose an a n aly s t wants t o com p are bar soap made from tallow with a liqui d ha nd soap m a de from

sy nt hetic ingr edients. Because the two products have different raw materi al sources (cattle an d petroleum ) , the analy s is sh ould begin wi th the raw materials acquisition step. Be cause the two products are packaged differently an d m a y have different che m ical for m ulas, the material s manufacture and packaging steps would nee d to be i n clud ed. Consum er use and waste m a nagement opti ons also shoul d be

exam ined because the different form ulae could resu lt i n var y ing usage patterns. Thus for this

co m p arative analy s is, the analy s t would have to in ventory the entire life cy cle of the two products.



### 15Again, the analy s t m u st deter m ine the ba sis of co m p ar ison between the sy stem s. Becaus e one soap is a

solid and t h e other is a liquid, each with differe nt densities and cleansing abilitie s per unit amount, i t
would not m a ke sense to com p are the m b ased on equal we ights or volum e s. The key factor is how m u ch

of each is use d in one handwashing to provide an e quivalent level of function or service. An a cceptable

basis for co mparison m i ght be equal num b ers of handw ashings. Because these two product s m a y be used at different rates, it would be im por tant to find data th at give an equ i valent use ratio. For exa m ple, a research lab study m a y show that five cubic m illi mete rs of bar soap and ten cubic m illi meter s of liquid soap are used per handwashing. If the basis for co m p arison were chosen at 1,0 0 0 handwashin gs, 5,0 00

cubic m illi meters of bar soap would be c o m p ared to 10,000 cubic milli m e t e rs of liquid soap. Thus, the equivalent us e ratio is 1 to 2.

Because the two soap product ty pes are packaged in different quantities and materials, the analy s t would need to include packaging in the s y stem

. Contributions of extra ingredients, such as perfumes

, m i ght also be considered. The analy s t may or m a y not find that a n y extra raw materi als ar e used in one or the other. Soaps ty pically m u st meet a m i ni m u m st andard performance l e vel.

However, if the liquid hand soap also had a skin m o i s turizer in its form ula, the analy s t would need to

include a m o isturizing loti on pro duct in the bou ndar y of the bar soap sy stem on two conditio n s . The first condition would appl y if t h e environm ental issues asso ciated with this com ponent were germane to the purpose of t h e LCA. The second condit i on, which is not as clear-cut, is if there i s actual value received by the consumer fro m incl usion of the m o i s turizer. If m a rket stu d ies indicate that consum e r s purchase the product i n pr eference to an identical pr oduct witho u t a m o isturizer, or if the y su bsequentl y us e a

m o isturizing lotion after us ing a no n-m o isturizing soap, then eq uiv a lent use would entail inclu d ing t h e separate moisturizing loti o n . Inclu d ing the m o is turizing loti on wo u l d m ove the com p arison beyond equivalent ha ndwashing to equivalent h a nd washing and skin m o isturizing.

In definin g s y stem boundaries, it is im portant to inclu d e every step that could aff ect the overall interpretation or ability of the analy s is to address th e issues for which it is being performed. Only in

certain well-d e fined instances can life-cy cle elemen ts such as raw materi als acq uisition or waste

manage ment be excluded. In general, only when a step is exactly the sa me in process, materi al s, and quantit y i n all alternatives consider ed, can that step be excluded fro m the sy stem

. In addition, the

fram e work for the com p ari s on m u st be r ecognized as relative becau se the total system values exclude

certain contributions. This rule is especi ally critical for LCAs used in public for u ms rather than for

internal com p any decision making. For exa m pl e, a co m p any com p aring alternative processes for producin g o n e petrochem i cal product may n o t need t o c onsider th e use and disposal of the p r oduct if the

final com posi tion is identic al. The com p any m a y also find that each pr ocess uses exactly the same

materials in the same am o unts per unit of prod uct ou tput. T h erefore, the co m p an y m a y consider the

materi als it uses as having no im pact in the study results. Another exam ple is a fi lling operation for

bottles. A com p any interested in using alternative materials for its bottles wh ile maintaining t h e same size and shape m a y not need to include filling bottles. However, if the original bottles wer e com p ared to

boxes of a dif f erent size an d shape, the f illing step would need to be included.



### 16Applications of System Expansion

Sy stem expansion broadens the sy stem boundaries an d introduces a new functional unit to m a ke the
two sy stem s being com p ared equal in scope. Ta ke for exam ple Product A which is produced b y Process AB along with co- p roduct B. Product A is to be com p ar ed to Product C which is the onl y product t o be produced by Process C. Using s y st em expansion, an alternative way t o produce

Product B is added to Proc ess C. The com p ari s on is now between Process AB and Process C plus

Process D.

Another appr oach to appl ying s y st em expansion is b y subtracting th e environm en tal burdens of an alternative way of pro duci ng Pro duct B (using the sam e exam ple as before) so that onl y Pr od uct A is

co m p ared to Product C. T h is appr oach is also referred to as the av oided burden approach since it is reasoned that the prod uctio n of an y alter n ative pr oducts is no longer needed and the resultant

environm ental burdens are avoided. T h e environm en tal burdens allocated to the product of in terest
are then calcu lated as the burdens from t h e process m i nus the burdens of an a lternative co-product.

For exam ple, a process that also generate s heat, such as a refrigerato r, offsets so me of the need for space heating which would be supplied by som e othe r source. The em issions avoided thr ough this

reduced de m a nd m i ght include em i ssions such as carb on di oxide, s u lfur di oxide, nitrogen oxi de,

carbon m onoxide and hydr ocarbons that are ty picall y em itted fro m power generation facilities. This

process can r esult in negative accounting of burdens i f the subtracted releases d o not occur in the main product sy stem

.

Resource con s traints for the life-cy cle inventor y m a y be considerations in defini n g the s y stem boun daries,

but in no case should t h e scientific basis of the study be co m p ro m i sed. The level of detail required to perform a thorough invent o r y depends o n the size of the sy stem an d the pur pose of the stud y. In a large

sy stem enco m p assing sev eral industries, certain details m a y not be significant contributors given the

defined intent of the study. These details may be om itted without af fecting the accuracy or application of the results. However, if the study has a very specifi c focus, such as a m a nufactur er co m p aring alternative

processe s or materi als for inks used in packaging, it w ould be im portant to include che m ical s used in very

sm all amounts.

Additional ar eas to consider in setting boundaries include the m a n u facture of capital equipm ent, energy
and em i ssions associ ated with personnel require m e n t s, and precom bustion i m pacts for fuel usage. These

are discuss ed later.

After the boundaries of eac h sy stem have been determin ed, a sy ste m flow diagra m
, as shown in Exhibit 2- 2, can be dev e loped to dep i ct the sy stem and direct e fforts to gather data for the life cy cle inve ntory

.



### 17Each sy stem step should be represented indivi duall y i n the diagram, includi ng the production steps for ancillary inputs or outputs such as chemicals and packaging.

Determin e the Ground Rules for Performing the Work

Prior to m oving on to the inventory analy s is phase it is i m portant to define some of the logistic al procedures for the project.

1. Documenting Assumptions - All assu m p t i ons or decisions m a de thr oughout t h e entire project m u st be reported along side the final results of the LCA pr oject. If assu m p tions are om it ted, the final results

may be taken out of context or easily m i s i nterpreted. As the LCA process adva nces fro m phase to phase, additional assu m p tions and lim itat i ons to the scope m a y be necessary to acco m p lish the project with the available resources.

2. Quality Assurance Procedures - Quality assurance procedures are i m portant to ensure that the goal and purpose for perform ing the LCA will be met at the conclusion of the project. The level of quality assurance procedures e m ploy ed for the projec t depends on the available ti m e and reso urces and how the r esults will be used. If the r esults are to be used in a public forum

, a formal review process is re c o mmended. A for m al revi ew process ma y consist of internal and external review by LCA experts and/or a review by interested parties to better ensure their support of the final results. If

the results are to be used for internal decision- making purposes only, then an internal reviewe r who

is fam iliar wi th LCA practices and is not associat ed with the LCA study m a y effectively m eet t h e quality assurance goals. It is reco mmen d ed th at a formal stat e m ent from the revi ewer( s )

docum enting their asse ss ment of each phase of the LC A process b e included with the final re port for the project.

3. Reporting Re quirements - Defining “up front” how th e final results should be do cu m e nted and exactly what should be included in the fi nal report hel p s to ensure t h at the final p r oduct m e ets the appropriate expectations. When reporti ng the final re sults, or results of a particular LCA phase, it is

im portant to t horou ghl y de scribe the m e thodol og y us ed in the anal y s is. T h e report shoul d ex plicitl y define the sy s t em s analy z ed and the bou ndaries that were set. The basis for com p arison among

sy stems and all assu m p tions m a de in per f orm i ng the work should be clearly explained. The presentation of results should be consist e nt with the purpose of the study

. T h e results should not be

oversi m plifie d solely for the purposes of presentation.



### 18Chapter 3 Life Cycle In ventory

What is a Life Cycle Inventory (LCI)? A life cy cle inventory is a process of quantify i ng en ergy and raw material require ments, at m o s pheric

em issions, waterborne em issions, solid wastes, and other releases for the entire l i fe cy cle of a product,

process, or ac tivity

.

Why Conduct an LCI?

In the life c y cle inventory phase of an LCA, all relevan t data is collected and orga nized. Without an LCI,

no basis exists to evaluate co m p arative environm enta l im pacts or potential im provements. The level of

accuracy and detail of the data collected i s refl ect ed throughout t h e rem a inder of the LCA process.

Life cy cle inventory analy ses can be use d in various way s . The y c a n assist an organization in com p a r ing products or processes and considering environm ental fact ors in m a t e rial sel ection. In additi on, inventor y analy ses can be used in pol i cy -m ak ing, by helping the governm e nt deve lop regulations regarding resource

use and envir onm ental emissions.

What Do the Results of t h e LCI Mea n ? An inventory analy s is produces a list co ntaining the quantities of pollutants released to the environm ent
and the am ou nt of energ y a nd m a terial consum ed. The results can be segregated by life c y cle stage, media (air, w a ter, and land), specific process es, or any com b ination thereof.

Key Steps of a Life Cycle Inventory

EPA’ s 1993 docum ent, “L ife-Cy cle Ass ess ment: Inventor y Gui d elines and Principles,” and 19 95

docum ent, “Guidelines for Assessing the Quality of Life Cy cle Inventor y Anal y s is,” provide the

fra m e work for perform ing an inventory analy s is and asse ssing the quality of the data used and the results.

The two docu m ents define the following four steps of a life cy cle inventory :

1. Develop a flow diagra m of the processes being evaluated.

2. Develop a data collection plan.

3. Collect data.

4. Evaluate and report results.

Each step is s u mmari zed below.

Step 1: Develop a Flow Di agram A flow diagram i s a tool to map the input s and outputs to a process or sy stem . The “sy stem ” or “sy stem
boundar y ” varies for every LCA project. The goa l defi nition and scoping phase establishes initial

boundaries that define what is to be incl uded in a particular LCA; t h ese are used as the sy stem boundar y for the flow diagram

. Unit processe s inside of the s y st em boundar y link together to form a co m p l e te life

cy cle picture of the require d inp u ts and outputs (m aterial and energy ) to the s y ste m . Exhibit 3- 1

illustrates the com ponents of a generic unit process within a flow di agram for a given s y stem boundar y

.



### 19Exhibit 3-1. Generic Unit Process

Transportation

Finished Parts/Components Materials/Parts/Components Process

Non-Hazardous Material Outputs Hazardous Material Outputs Electricity

Water

Gas

The m o r e com p l e x the flow diagram

, the greater th e accuracy and utility of the results. Unfortunately,

increased co m p l e xity also means m o r e time and reso urces m u st be devoted to this step, as wel l as the data collecting and analy z ing steps.

Flow diagrams are used to m odel all alt e rnatives under consideration (e.g., both a baseline sy stem and alternative syste m s). For a com p a r ative study

, it is im portant that both the baseline and alternatives use

the sam e sy stem boundar y and are m odeled to the same le vel of detail. If not, t h e accuracy of the results

may be skewed.

For data-gathering purposes it is appropr iate to view the sy stem a s a serie s of subsy s tem s . A “subsy s tem”

is defined as an indivi dual step or process that is part of the defined producti on s y stem . So m e steps in the

sy stem may n eed to be gro uped int o a su bsy s tem due to lack of specific data for the individual steps. For

exa m ple, sev eral steps ma y be required in the pro duction of bar soap from tallow (see Exhibit 3-2). However, these steps may all occur w ithin the sam e facility , which may not be able to or need to break data down for each individual step. The facility could however, provide data for all the steps together, so

the subs y s tem boundary would be dra w n around t h e gr oup of soap producti on steps and not around each

indivi dual on e.

Each subsy s t e m requires inputs of m a terials and ener g y ; requires t r ansportation of prod uct pr oduced; and has outputs o f products, co -products, at m o spheric em issions, waterborne wastes, solid wastes, and possibl y ot her releases. For each subsy s tem

, the i nventor y anal y s t should describe material s and energy

sources used and the t y pes of environm ental releases. The actual activities that occur should a l so be

described. Data should be gathered for t h e am ount s and ki nds of m a terial inputs and the t y pes and quantities of energy i nputs. The e nvironmental releases to air, wat e r, and land s hould be qua ntified by type of pollutant. Data collected for an inventory should alway s be associat ed with a quality mea s ure. Although for m al data qual ity indicators (DQIs) su ch as accuracy
, precision, representativeness, and



### 20co m p leteness are strongl y preferred, a description of how the data were generat e d can be useful in judging quality.

Exhibit 3-2. Detailed System Flow Diagram for Bar Soap

Co-products f r om the process should be i d entified a nd quantified. C o -products are process outputs that have value, i.e., those not t r eated as wastes. The value assigned to a co-product may be a m a r k et value (price) or may be im puted. In perform ing co-pro d u ct allocation, some means m u st be found to objectivel y assign the resource use, energ y consum p tion, and em issi ons am ong the co-products, because there is not a phy s ical or che m ical w a y to separate the activities that produce them . Generall y, allocation

should allow technically so und i nventori es to be prepar ed for prod u c ts or m a terials using an y p a rticular
output of a pr ocess independentl y and wi thout overlap of the other outputs.



### 21In the m e at packing step of the bar soap exa m ple, sev eral co-products could be identified: m e at, tallow,

bone m e al, blood m eal, an d hides. Othe r exam ples of co-products are the trim scraps and off-spec

materi als from a m o lded plastic plate fabricator. If the tri m scr aps and off-spec materi als ar e used or marketed to other manufacturers, they ar e consider ed as co-products. Industrial scrap is the common

nam e given to such m a t e ri als. If the trim i s discar ded into the solid waste stream to be landfilled, it

should be included in the solid waste from the process. If the trim or off-spec m a terials are reused within the process, they are considered “home scrap,” whic h is part of an internal recy cling loop. These

materi als ar e not included i n the invent or y, becau se they do not cross the bounda ries of the subsy s tem

.

All transportation from one process locat ion to another is included in the subs y s te m

. Transportation is quantified in term s of distance and weight shipped, and identified by the m ode of transport used.

Step 2: Develop an LCI Data Collection Plan As part of the goal definition and scoping phase (discussed in Chapter 2), the re quired accuracy of data

was deter m in ed. When selecting sources for data to com p let e the life cy cle inve ntory

, an LCI data collection plan ensures that the quality a nd accuracy of data m eet th e expectations of the decision-m a ker s

.

Key elem ents of a data collection plan in clude the foll owing:

• Defining data qualit y goals

• Identify i ng data sources a nd types

• Identif y i ng data quality indicators

• Developing a data collecti on worksheet and checklist.

Each ele m ent is described below.

Define Data Quality Goal s - Data quality goals provide a framewo rk for balancing available tim e and resources against the quality of the data required to make a decision regarding overall environm ental or hum an health im pact (EPA 1986). Data quality goals are closely linked to overall study goals and serv e two prim ary purposes:

• Aid LCA pr actitioners in structuring an approach to data collection based on the data quality needed for the analy s is.

• Serve as data quality performance criteri a.

No pre-defined list of data qualit y g o als exists for all LCA projects. The num ber and nature o f data qualit y goals necessary depends on the le vel of accuracy required to inform the decision- m a kers involved in the process.

Exam ples of Data Quality Goals

The following is a sam p le list of hy pothetical data quality goals:

• Site-specific data are r e quired for raw materi al s and energy in pu ts, water consu m ption, air

em issions, water effluents, and solid wa ste generation.

• Approxim a te data values ar e adequate for the energy data cat egory.

• Air em ission data should be representati ve of sim i l a r sites in the U.S.

• A m i ni m u m of 95 percent of the m a t e rial and energy i nputs should be accounted for in the LCI

.



### 22Identify Data Quality Indic a tors - Data qualit y indicat ors are benchmar ks to which the collected data can

be measured to determ ine if data qualit y requirem e nts have been met. Sim ilar to data qualit y g o als, there is no pre-defi ned list of dat a qualit y in di cators for all LCIs. The selection of dat a qualit y in di cators depends upon which ones are m o st appropriate and applicable to the specific dat a sources bei ng evaluated. Exam ples of data quality indicators are precision, co mpleten ess, rep r esentativeness, consistency

, and reproduci b ilit y

.

Identify Data Sources and Types - For each life cy cle stage, unit process, or ty pe of environmental

releas e, speci fy the necess ary data source and/or ty pe required to provide suffic i ent accuracy and quality

to m e et the st udy’ s goals. Defining the required data sources and types prior to data collection helps to

reduce costs and the tim e r e quired to collect the data.

Exa m ples of data sources i n clude the following:

• Meter readin gs from equipment

• Equipm ent operating logs/ j ournals

• Industr y data reports, databases, or consultants

• Laboratory test results

• Government docum ents, r e ports , databases, and clear inghouses

• Other publicl y available databases or clearinghouses

• Journals, pap e rs, books, an d patents

• Referen ce books

• Trade associ a tions

• Related/previous life cy cle inventor y stu d ies

• Equipm ent and process spe c ifications

• Best engineering ju dgm ent.

Exam ples of data types include:

• Measured

• Modeled

• Sam p led

• Non-site specific (i.e., surrogate data)

• Non-LCI data (i.e., data not intended for the purp o se of use in an L C I)

• Vendor data.

The required level of aggregated data should also be s p ecified, for exam ple, whether data are representativ e of one proc ess or sever al processes.

A num ber of sources should be used in c o llecting da ta. Whenever possible, it is best to get wellcharacterized industr y data for production processes. Manufacturing processes o f ten beco m e m o r e efficient or change over time, so it is im portant to seek current data. Invent ory data can be facility

specific or more general and still rem a i n current.

Several cat egories of data are often use d in inventories. Starting with the m o st disaggregated, these are:

• Individual process- and facility -specific: da ta from a particular operation within a given facility that a r e not com b ined in any wa y.

• Co m posite: data fro m the sam e operatio n or activit y c o m b ined acro ss locations.



### 23• Aggregated: data co m b ining m o re than one process operation.

• Industr y

- average: data derived from a represen tative sam p le of locations and beli eved to statistically describe the typical operation across tech nologies.

• Generic: data whose representativeness may be unknown but whic h are qualitatively descriptive of a process or technology.

Co m p lete and thoro ugh i n v e ntories often require use of data considered proprietary b y either t h e manufacturer of the produc t, upstream suppliers or ve ndors, or the L C A practitioner perform ing the study

. Confidentialit y issues are n o t relevant fo r life-cy cle in ventories conducted b y co m p anies using their own facility data for internal purposes. However, the use of proprietary data is a criti cal issue in inventories

conducted for external use and whenever facility -speci fic data are o b tained from external suppliers for

internal studies. As a cons equence, current studi es often contain in sufficient source and documentation data to perm it technically s ound external review. Lack of technically soun d data adversely affects the

credibilit y of both t h e life-cy cle invent ories and the method for perform ing them . An individual

co m p any’ s tr ade secr ets an d com p etitive technologies m u st be protected. When collecting data (and later when reporting the results), the protection of confi d ential business inform ation s hould be weighed against

the need for a full and detailed analy s is or discl osure of inform ation. Som e form of selective

confidentialit y agreem ents for entities perform ing life-cy cle invent ories, as well as form alization of peer review procedures, is often necessary for invent ories th at will be used in a publi c forum

. Thus, industr y data m a y need to undergo i n term ediate confidential re view prior to beco m i ng an aggregated data source

for a docum e n t that is to be publicly released.

The purpose, scope, and bo undar y of the inventor y he l p the anal y s t determ ine the level or t y pe of

inform ation that is required. For exam ple, even wh en the analy s t c a n obtain actual industr y d a ta, in what

form and to what degree should the analy s t sh ow th e data (e.g., the range of valu es observed, industr y average, plant-specific dat a , and best available c ontrol techniques)? These questions or decisions can usually be answer ed if the purpose or scope has been well defined. T y picall y , most publicl y available life-cy cle documents present ind u str y av erages, while many internal industrial stu d ies use plant-specific

data. Reco mmended pract ice for external life-cy cle i nventory studies includes the provision of a measur e of data variabilit y in additi on to average s . Freque ntl y , the m e asure of variabilit y will be a stati s tical

para m e t e r, such as a standa rd deviation.

Exam ples of private indust r y data sources include inde pendent or i n ternal reports, periodic measurements, accounting or engineering r e ports or data sets, speci fi c mea s ure m ents, and m a chine specific a tions. One particular issue of interest in considering industrial sources, whether or not a for m al public data set is established, is the influence of industr y and rela ted technical associ ations to enha nce the accur acy
, representativ eness, and currentness of the collected da ta. Such associations may be willing, w ithout providi ng spe c ific data, to confirm that certain da ta (about which t h eir mem b ers are knowledgeable) are

realistic.

Government docum ents an d data bases provide data on broad categories of processes and are publicl y available. Most governm e nt docum ents are published on a perio d i c basis, e.g., annuall y , bien niall y , or

every four y e ars. However

, the data published with in the m tend to be at least sev eral y ears old.

Furtherm ore, the data found in these doc uments m a y be less specif i c and less accurate than industr y data for specific facilities or groups of facilities. Howeve r, depending on the pur pose of the study and the specific data objectives, these li m i t a tions m a y not be critical. All studies should note the age of the data

used. Som e useful govern ment documents include:

• U.S. Department of Commerce, Census of Manufacturers

• U.S. Bureau of Mines, Census of Miner a l Industries



### 24• U.S. Department of Energ y , Monthl y En ergy Review

• U.S. Enviro n m ental Protection Agenc y , Toxics Release Inventor y ( T RI) Database.

Government data bases inc l ude both non-bibliograp hic types where the data ite ms the m selve s are contained in t h e data base and bi bliographic t y pes th at consist of references wher e data m a y be found.

Technical books, reports, conference papers, and articles published in technical journals can also provide

inform ation and data on pr ocesses in the sy stem . Most of these are publicl y avail a ble. Data presented in

these sources are often older, and the y ca n be either too specific or not specific enough. Many of these

docum ents gi ve theoretical data rather than real da ta f o r processes. Such data may not be representative of actual processes or m a y deal with new technologi es not commercially tested. In using the technical

data sources i n the following list, the analy s t should c onsider the date, specificit y , and relevancy of the

data:

• Encyclopedia of Chemical Technology , Kirk-Oth m e r

• Periodical tec hnical journals such as Journal of the Water Environment Federat i on

• Proceedings from te chnical conferences

• Textbooks on various appli e d sciences.

Surve y s designed to capture information on a represen tative sa m p l e of end users can provide current
inform ation on the parameters of product or service use. Surve y s t ypically center around a q u estion:

• How long or how many ti mes is a product or servi ce used before it is discarded (e.g., the num ber of

y ears a television set has been in u se and is expected to be in use)?

• What other materials and what quantities of these ma terials are used in conjunction with produc t use or maintenance (e.g., m o isturizing loti o n used after hand washing)?

• How frequent is the need for prod uct repair or m a intenance (e.g., how often is an appliance repaired over its lifetime, and who does the repair)?

• What other uses does the product have bey o nd its ori g inal purpose?

• What does th e end user do with the prod uct when he o r she is throu gh with it ?

Frequentl y , t h e end user will not be able to suppl y sp e c ific information on inputs and out puts. However, the end user can provide data on user practices fro m w h ich inputs and outputs can be derived. Generally

, the end user can be the source of related i n form ati on from which the energy, m a terials, and poll u tant
release inventor y can be de rived. (An ex ception woul d be an instit utional or co mmercial end user who

may have some infor m ati on on energy consum ption or water efflu e nts.) Market resear ch fir m s can often provide qualit ative and qua ntitative usage and customer preference data without t h e analy s t ha ving t o perform independent m a rk et survey s.

Recy cling pr ovides an exam ple of so m e of the strengt hs and lim itations encounte r ed in gatheri ng data.

For som e pro ducts, economic-driven re cy cling has been practiced for many y e a r s, and an infrastructure

and m a rkets f o r these m a terials already exist. Data ar e typically available for these products, i n cluding

recy cling rates, the consumers of the recl ai m e d materi als, and the resource require m e nts and

environm enta l releas es for m the r ecy cling activities (collection and reprocessing). Data for materi als currently at low recy cling rates with ne wly form ing r ecy cling infrastructures are m o r e difficult to obtain. In either case, often the best source for data on r esource require me nts and environm ental rel e ases i s the processors the m s e lves. For data on recycling rates and recy cled material, consumers and processors may be helpful, but trade associ ations as well as the consumer s of the re cy cled m a te rials can also p r ovide data.

For m a t e rials that are recy cled at low rates, data will be m o re difficult to fi nd.



### 25Two other areas for data gathering relate to the s y stem as a whole and to com p arisons between and am ong

sy stems. It is necessary to obtain data on the wei ghts of each co m ponent in the product evaluated, either by obtaining product specifications from the manufac turer or by weighing each com ponent. These data

are then used to com b ine the individ u al com ponents in the overall sy stem analy s is. Equivalent use ratios for the pro d u c ts co m p ared can be developed b y su r v ey i ng retailers and consum ers, or b y revie w ing

consumer or trade associ ati on periodicals.

Develop a D a ta Collection Spreadsheet – The next step is to develop a life cy cle inventory spreadsheet

that covers most of the decision areas in the perfo r m a n ce of an inventory (see A ppendix A which shows a

sa m p le inven t ory spreadsheet). A spre a d sheet can be prepared to guide data collection and validation a nd

to enable construction of a database to store coll ected data electronically. The following eight general

decision areas should be a ddressed in the inventor y s p readsheet:

• Purpose of th e inventor y

• Sy stem boun daries

• Geographic scope

• Types of data used

• Data collection procedures

• Data quality measures

• Co m putational spreadsheet construction

• Presentation of results.

The spreadsh eet is a valua b le tool for ensuring com p le teness, accu racy , and consistency

. It is espe c ially

i m portant for large project s when sev er al people co llect data fro m m u ltiple sources. The spreadsheet

should be tailored to m eet the needs of a specific LCI.

The overall sy stem flow diagram

, derived in the previ ous step, is im portant in constructing t h e

co m putational spreadsheets because it numeric ally defin es the relati onships of the individual subs y s te m s to each other in the product i on of t h e final product. T h ese numerical relationships become the source of “proportionality factors,” which are quantitative relationshi ps that reflect the relative contributions of the subsy s tem s t o the total s y s t em . For exam pl e, data fo r the prod uctio n of a particul ar ingredient X of bar soap are developed for t h e productio n of 1,00 0 to ns of X. To pro d u ce 1,000 t ons of bar soap, 2 50 to ns of X are needed, accounting for losses and in efficiencies . Thus, to find the contributions of X to the total

sy stem , the data for 1,000 tons of X are m u ltiplied by 0.250.

The spreadsheet can be used to m a ke other co m puta tions beyond weightin g the co ntributi ons of various subsy s tem s

. It can be used to translate energy fuel val u e to a standard energy uni t , such as m illion British

therm a l unit (Btu) or gigaj oule (GJ). Preco m bustion or resource acquisition ene r g y can be co m puted by appl y i ng a standard factor t o a unit quant ity of fuel t o account for energ y used to obtain and tr ansport the fuel. Energy sources, as w e ll as ty pes of waste s , can be categorized. Credits or charges for incineration

can be derived. Fuel-related wastes should also be calculated based on the f u els used throughout the

sy stem . The spreadsheet should also in corporat e waste m a nagement opti ons, su ch as recy cling,

co m posting, and landfilling.

It is im portan t that each subsy s tem be incorporated in the spreadsheet with its related co m ponents and that each be linked together in such as way that inadvert ent om issions and double-counting do not occur. The spreadsheet c a n be organiz e d in several different ways to acco m p li sh this purpose. These can include allocating certain fields or areas in the s p readsheet to certain ty pes of calculations or using one type of spreadsheet s o ftware to act ually lin k separate spre ads h eets in hierarchi cal fashio n. It is im perative,



### 26however, once a sy ste m of organization is used, that it be e m ploy ed consistently

. Haphazard organization of data sets and calculations generally l eads to faulty inventor y results.

Many decisions m u st be made in every l i fe-cy c le inve ntor y anal y s is . Ever y in ventor y co nsists of a m i x of

factual data and assum p tio ns. Assu m p tions allow the an aly s t to eva l uate a sy stem condition when factual

data either cannot be obtai ned within t h e context of t h e study or do not exist. E ach piece of inform ation (e.g., the weight of paperb oard used to package th e soap, ty pe of vehicle and distance for shipping the tallow, losses incurred when rendering ta llow, or em is sions resulting from the an i m als at the f eedlot), fall into one or the other category and each play s a role in developing the overall syste m analy s is . Because

assu m p tions can substantially affect study results, a ser ies of “what if” calculati ons or sensitivity analy ses are often performed on the results to examine the effe ct of making changes in the sy stem . A sensitivity analy s is will t e m porarily modif y one or m o re para met e rs and affect the calculati on of t h e results. Observing the change in the results will help determ in e how im port a nt the assu mptions are with respect to

the results. The com putati onal spreadsheet is also us ed to perform these sensitivi t y analy s is calculations.

Decision Points within Life Cycle Inve ntory

During the 2003 InLCA/L C M conference in Seattle, Washington, a session was organized with the specific intent of initiating open discussion on inve nt ory m e thodology and determining if ther e was support behin d the idea of developing in ternationa l pr ocedural guid e lines for inv e ntor y , g o ing beyond

the ISO 14040 and 14041 guidance. The general consensus of the group in Seattle was that there is a

need and desire for m o re detailed guidance, esp ecially around the f o llowing list of suggested key decision points within life cy cle inventory :

• Co-product al location

• Recy cling allocation

• Exclusion of sm all amounts

• Exclusion of spills and los ses

• Age-appropriateness of dat a

• Surrogate and esti m at ed data

• Inventory for i m pact as ses s m ent

• Matching the goal to t h e method

• Collecting pri m ary data

• Report format

• Iterative procedure for data collection

• Choosing bo undaries

• Capital equipment/infrastructure exclusions

• Tim e and location m e ta data.

Someti m e s it is helpful to think ahead about how the results will be presented. This can direct so m e decisions on how the spreadsheet output is specified. The analy s t m u st re me m b er the defined purpose for perform ing the analy s is and tailor the da ta output to those expresse d needs. For exa m ple, the analy s t might ask: Is the purpose of the life-cy cle inventory t o evaluate the overall sy ste m results? Or is it expected that detailed subsy s tem info rmation will be analy zed in r e lation to the total? Will the study be used in a public forum ? If so, how? How m u ch deta i l is required? Answers to questions such as these will help determ ine the com p l e xity and the degree of generalizatio n to build i n t o the spreadsheet, as well as the appropriate presenta tion of results

.



### 27Step 3: Colle ct Data

Data colle ction efforts involve a co m b ination of resear ch, site-visits and direct contact with experts, which generates large quantities of data. As an alte rnative, it m a y be m o re cost effective to buy a

co mmercially available LC A software p ackage (se e Appendix B). Prior to purc h asing an LCA software package the decision-m a kers or LCA practitioner should insure that it will provi de the level of data analy s is requi red.

A second m e t hod t o reduce data collecti on tim e and r esources is to obtain non-si te specific in ventor y data. Several organizations have de veloped databases specifically for LCA that contain som e of the basic

data co mm on ly needed in c onstructing a life cy cle inventory

. Som e of the databases ar e sold in conjunction with LCI data collection software; others are stand-alone resources ( see Appendix B). Many

co m p anies wi th proprietary software also offe r consulting services for LCA design. The use of

co mmercial s o ftware risks losing transpa r ency in the data. Often there is no record of assum p t i ons or

co m putational methods that were used. This may no t be appropriat e if the results are to be used in the public dom a i n . Revisiting the goal statement is needed in or der to determ ine if such data are appropriate.

All industrial processes have m u ltiple input stream s a nd m a ny generate m u ltiple output streams. Usually only one of the outputs is of interest for the life cy cle asses s m ent study being conducted, so the analy s t
needs to determine how m u ch of the energy and m a teri al require m e n t s and the environm ental re lease s associat ed wi th the process should be attributed, or allocated, to the producti on of each co-product. For

exam ple, steam turbine sy stem s may sell both electricity and low-pr essure st eam as useful products. When co-products are present, the practitioner m u st deter m ine how m u ch of the burdens associated with operating and suppl y i ng t h e m u lti-output process should be allocated to each co-product. The practitioner

m u st also decide how to all o cate environmental burde ns across co-products when one is a waste stream

that can be sold for other uses.

The guidance provi ded by t h e International Standa rds Organization (ISO) recognizes the variet y of approaches that can be use d to treat the allocation i ssue and, therefore, requires a step-wis e a pproach (see

text box on I S O 14041). The standard calls for pract iti oners to avoid allocation if possible; and secondl y , to m odel approaches which reflect the phy sical relati onships between the process outputs and its inputs. Proper application of the I S O guideline s on allo cation requires a good understanding of the p h y sical relationships between co-products in a process.

Although avo i ding allocati on is favored b y the ISO st a ndard, it is n o t alway s pos sible to expan d sy stem s in all cases. And, as alluded to earlier, allocation ca nnot be totall y avoided even in a sy stem expansion approach. Th erefore, other optio ns m u st be used.

Although m a ss has m o st o f ten been used as a basis for allocation, allocation b y volum e is done in a

si m ilar way

. Methods based on m a rket value usually i n clude expected econom ic gain based on gross sales. However, none of t h ese methods offers a gene r a l solution. Allocation may seem i m pr actical in

cases where o n e product fa r outweighs another. Altho ugh m a rket value in m o st cases r e flect s the use of

energy and therefore many of the associa t ed burdens, a llocation on this basis covers only one aspect of the sy stem

. Also, m a rket value is highly variable over ti m e , so metimes up to 50 percent in a short tim e period. Alloc a tion on an equal basis (50 / 50) or on an “all or none” basis (100 pe rcent to one p r oduct) can be considered to be a highly arbitrary choice.

Environm ental burdens related to the alternative sy stems m u st still be m odeled u s ing an appropriate method where co-products are generated. A lot has b een publishe d in the open literature on the subject in

an effort to better understand the c onsequences of allocation choices.



### 28ISO 14041: 6

. 5.3 Allocati o n Procedure

On the basis of the princip l es m e ntioned above, th e fo llowing step wise procedure shall be applied.

Step 1: Wher ever possible, allocation should be avoid e d b y :

1) Dividing t h e unit pr ocess t o be allocated into two or m o r e subprocesses and collecting the input

and out put da ta related to these subprocesses. 2) Expanding the product s y st em to include the additional functions rel a ted to the co-products, taking int o account the req u irem ents of (func tion, f u n c tional unit, a nd reference flow).

Step 2: Wher e allocation cannot be avoi ded, th e in put s and outp u ts of the s y stem should be partitioned be tween its different pr oduct s or functions in a way whi c h reflects th e underl y i ng phy s ical relationships between them, i.e., the y sha ll refl ect the way in which the inputs and outputs are changed by quantitative changes in the products or functions delive r ed by the s y s t em . The resulting

allocation will not necessar ily be in proportion to an y si m p le measu rem e nt such as m a ss or m o lar flows of coproducts.

Step 3: Wher e ph y s ical relationship alo n e cannot be established or used as the basis for allocation, t h e inputs sho u ld be allocated between the products and f unctions in a way which reflects other relationships between them. For exam ple, input an d o u tput data m i ght be allocated between coproducts in proport i on t o the econom ic value of the products.

The flow diagram ( s) developed in Step 1 prov ides th e road map for data to be collected. Step 2 specifies the required data sources, t ypes, qualit y , accuracy , and collection methods. Step 3 consists of finding and filling in the f l ow diagram and worksheets with num eri cal data. This m a y not be a si m p le task. Som e data m a y be d i fficult or impossible to o b t ain, and th e available data may be diffic u lt to convert to the

functional u n i t needed. Th erefore, the sy stem bounda ri es or data qualit y goals o f the stud y m a y have t o be refined based on data availability

. Th is iterative process is co mm on for m o st LCAs.

Inputs in t h e Product Life-Cycle Inventory Analysis

The decision on which raw/intermediate materi al requi re m e nts to include in a life-cy cle inventory is

co m p lex, but several options are availab l e:

• Incorporate all requirements, no m a tter h o w m i nor, on the assu m p tion that it is not possible a priori to deci de to exclude any t hing

.

• Within the defined scope of the study

, e x clude inputs of less than a predeter m i ne d and clearly

stated threshold.

• Within the defined scope o f the stud y , e x clude in puts determ ined likely to be negligible, relat i ve to the intended use of the i n form ation, on the basis of a sensitivity a n aly s is.

• Within the defined scope, consistentl y ex clude certain classes or ty p es of inputs, s u ch as capital equipm ent replacement.

The advantage of the first option is that no assum p tio ns are m a de i n defining and drawing the sy stem
boun dar y . T h e analy s t d o es not have to explain or defend what has been include d or excluded

. The disadvantage is that application of t h is approach could be an endless exercise. The num ber of inputs

could be ver y large and could inclu d e some sy stem s onl y distantl y related to the product s y ste m of



### 29interest. Besi des the co m putational complexity , inte rpretation of the results wit h respect to the single desired produ ct, package, or activity co ul d be difficult.

The second o p tion, if im plem ented with full explanati on of what t h e threshold is and wh y it w as selected,

would have t h e advantages of consistency and lower cost and time investm e nts. Two subopti o ns can be identified, de pending on t h e nature of th e thres hold. One suboptio n is to specif y a percentage
contributi on below which the material will be excluded, for example, one percent of the i nput to a given subsy s tem or to the entire sy stem . The one percent rule historically has been usef ul in lim iting the extent of the analy s is in inventories where the environm en tal consequences of quantitatively m i nor materi als ar e not considered. The disadvantage of the one pe rcent rule is that the possible presence of an

environm entally dam a ging activity associated with these materials could be overl ooked. Also, when used

with m i xed percentages (e.g., percent of sy stem ener gy, percent of subsy s tem input), the resul t may be confusing or i n consistent. The sc oping analy s is shou ld pro v ide a rationale for choosing to ap pl y such a

rule.

The second subopti on is t o set a threshold based on t h e num ber of steps that the raw/inter m ediate m a t e rial

is re m oved from the main process seque nce. Consider the bar soap exa m ple disc ussed earlier. Caustic

manufacture f r om brine ele c troly s is is pa rt of the m a in process sequ e nce and would clearly be included.

Sodium carbonate is an input m a t e rial fo r the prod uction of caustic is therefore a secondary input. Appl y i ng a “one-step back” decision rule would in clu d e the steps associated with sodium carbonate productio n. Amm oniu m chloride is an i nput m a teri al for the pro d u c tion of sodi u m carbonate using the

Solva y process. Relative t o caustic, a m m oniu m chlo ri de is a tertia ry input and would be exc l uded if a “one-step back” decision rule were a pplied. As in the first option, t h e “one-step back” decisio n rule has the advantages of clarity an d consistent application. F o r some input s that are analy zable in exa c t
mathematical term s, the “o ne-step b ack” rule may be j u stifiable. If the inputs t o a given proce ss bear a fixed relationship to the next-tier process, one step is all that may be neces sary to obtain a sufficiently

accurate valu e (Boustead and Hancock 1979).

Consider the exa m ple of a refinery . Most of the re finery’s out put i s sold for pro duction of pet r oleum

based m a t e ria l s. However, a s m all portion, say eight pe rcent, is use d to run the refinery . This portion,

term ed the parasitic fraction, is m a thema tically related to the refinery out put as:

M(1+f)

where: M is the outp u t pro duct an d f is the parasi tic fraction (0.08)

For a life-cy cle inventory on a petroleum-based plas tic , the prima r y output of the refinery clearly would

be included within the s y stem boundar y

. Sup pose t h e data qualit y in dicators showed that t h e data were

accurate to + 5 percent. Be cause of the f i rst-tier use o f the m a teri al represents an eight percent difference, a “one-step back” rule would inclu d e the refinery m a t e rial (f uel) output used to run the refinery

. However, to produce the materi al (fuel) to run the r e finery requir es a further fraction of the output two steps back for the plastic raw m a te rial. This is calcul a ted as:

M(1+f+f 2 ).

Thus, the incr em ental contr i bution of t h e second step b ack is 0.6 pe rcent, which is less than the data

accura cy . That is, there is no significant difference in the sy stem da ta after the fir s t step. Disa dvantages of this approa ch include th e lack of simple geom et ric relationships for m a ny inp u ts and the in creased effort to analy ze m o re tier s as data qual ity increases.



### 30The third opti on, drawing boundaries based on sens itivity anal y s is, adds the advantage of being

sy stematic rat h er than arbitrary in assigning the thr eshold. The disadvantages of a sensitivity a n aly s isbased approach are that the analy s t needs to be very clear in descr ibi ng how the analy s is was used and, unless a large existing database is available to supply pr eli m inary values that can be used in the sensitivity analy s is, the r e quired analysis effort m a y not be lim ited b y a ver y large am ount. A m o re in-depth

discussion of sensitivity analy s is is provi d ed later in this chapter.

The final opti on, excludi ng certain classes or types of input, also h as been found throu gh expe rience to apply to m a ny sy stem s. F o r exa m ple, in the bar soap inventor y, a decision may be made to exclude the equipm ent used to cut the bars of soap. The justif ication is that the allocation of i nputs and out puts from

the manufacture of the m a chine is m i nuscule when the m illions of bars of soap produced by the m a chine

are considere d . The advantage of this option is that many com p lex subs y s tems can often be excluded. The disadvantages are the sa me as those for the first op tion, namely, that a highl y significant activit y m a y be elim inated . Capital equipment is the m o st co mm o n l y excluded input t ype. T h e analy s t sh ould perform a pre lim inary analy s is to characterize the basi c activities in each cla ss or type of input to ensure that a significant contributi on is not left out.

Energy Energy represents a co m b ination of energy requireme nts for the subsy s tem

. Three categories of energy are quantifiable: process, tr ansportation, and energy of material r eso urces (inhere nt energy ).

Process energ y is the energy required to operate and r un the subs y s te m proces s(e s ), including such ite m s

as rea c tors, heat exchanger s , stirrers, pum p s , blowers

, and boilers. Transportation energy is the energy required to power various m ode s of transportation suc h as trucks, rail carriers, bar g es, ocean vessels, and pipelines. Co nve y o rs, fork lifts, and othe r equipm ent that could be c onsidered with transportati on or process are l a beled according to t h eir rol e in the subs ystem

. For exam ple, power supplied t o a conve y o r used to carry materi al fro m one point in the subsy s tem would be labeled process energy . On the other hand, the po wer supplied to a conve y o r used to tran s port m a terial from one subsy s tem to a different subsy s tem would be considered transportation energy.

Two alternatives exist for incorporating energy i npu ts in a subs y s tem module. One is to report the actual

energy f o rm s of the inp u ts, e.g., kilowatt- hours (kWh) of electricity or cubic feet of natural gas. The

other is to inc l ude the specific quantities of fuels u sed to generate the produced energy form s in the

m odule.

The advantage of the first approach is that the speci fic energy m i x is available for each subsy s te m

. For

exam ple, a co m p any m a y want to evaluate the desi rabilit y of installing a natural gas-fired boi ler to produce steam co m p ar ed to using its electrically h eated boiler pow ered by a com b ination of purchased and on-site generated ele c t r icity

. A specific fuel m i x could be app lied to com pute the energy and fuel

resource use. The second approach, incorporating spe c ific fuel quantities, allows a subsy s tem co m p arison of prim ary energy fuels. For exa m ple, “ x ” kilowatt- hours of electricity would be specified as “y ” cubic feet of natural gas and “z” pounds of ura n ium

.

Within each subs y s tem

, the energy input data shoul d be given as specific quantities of fuel and t h en converted int o energy equi valents accor d ing t o th e conversion factors discussed in the foll owing two

sections. For exa m ple, the energy require m e nts attribut ed to a polyethy lene resin plant m a y be specified as 500 po und s of eth y lene for feedstock, 500 cu bic feet of natural g as, 50 kilowat t -hours of ele c tricity to run the process equipment, and 50 gallons of diesel fuel to transport the resin to consumers. I n this case,

the 50 ki lowatt-hours woul d be converte d to 1 80 m e gajoules.



### 31Co m bustion and Preco m bustion Values To report all energy usage associat ed wi th the subs y s te m of concer n, the analy s t may need to c onsider

energy data bey o nd the primary process associat ed wi th com bustion of the fuel. The energy used in fuel

co m bustion i s onl y part of the total energy associated with the use of fuel. The am ount of energy expended to a c quire the fuel also m a y be significant in co m p arison to other energy expenditures. Energy to acquire fuel raw m a t e rial s (e.g., m i ning coal or dr illing for oil), process thes e r a w materials into usable fuels, and transport them is term ed by various prac titioners as “preco m bustion energy ” or “energy of fuel acquisition.” Preco m bustion energy is de fined as the total am ount of energy necessary to deliver a usable

fuel to the consumer of the fuel.

Including preco m bustion energ y is analogous t o extending the s y st em boundaries for fuels to raw material inputs. F o r exam ple, suppose the co m bustion of f u el o il in an i ndu strial boiler results in the release of about 150,000 Btu per gall on. However, crude oil dr i lling and production, refining, and transporting the fuel oil requir e an additional 20,000 Btu per gallon. This additional energy is t h e preco m bustion energy

. Thus, the tota l energy expe nded (precombustion energ y plus com bustion energ y ) when a gallon of fuel o il is consumed would be 170,000 Btu. Generally , a co m p lete inventor y will include preco m bustion energy

contributions because they represent the true energy de m a nd of the sy stem . Inclusion or exclus ion of this

contributi on s hould be clearly stated.

Energy Sourc e s Energy is obt ained from a variety of sources, including coal, nuclear power, hy dr opower, natur a l gas, petroleum

, wind, solar energ y , solid waste, and w ood biom ass. Fuels are interch a ngeable, to a high degree, based on their energy content. For exam ple, an electric utility decides which fuel or other energy

source to use based on the cost per ener gy unit. U tilities can and do use m u ltiple for m s of energy sources, making possible an economic decision based on the energy cost per kilowatt-hour of electricity generated. Manufacturing com p anies also choose am ong energy sour ces on the same basis. However, reasons other than cost, such as scar city or e m issions to the envir onment, also aff ect the energy source decision. For

exam ple, during perio d s of petroleum sh ortages, findi ng pro ducts t h at use predo m inantly non -petroleum

energy sources m a y be desirable. For that reason, th e inventory should characteri ze energy require m ents according to basic sources of energy . Thus, it would consider not only electricity, but also the basic sources (such as coal, nuclear power, hydropower, na t u ral gas, and petroleum ) th at produce the electricity

.

Electricity : C onsiderations associat ed wi th electricity incl ude the source of fuel used to generate the electricity and the efficiency of the generating sy st e m . Power utilities ty pically use coal, nuclear power, hy dropower, natural gas, or oil to generate elect ricity . Non-utility genera tion sources can include wind
power, waste-to-energ y , and geot hermal energy. Accurately determining electrical energy us e and

associat ed e m issions raises several co m p l i cations, such as relating the actual ele c tr icity use of a single

user to the actual fuel used.

Although a gi ven com p any pay s its bills to a partic ular utilit y , the com p any is not sim p ly purchasing power from t h e nearest pla n t. Once elec tricity is generated and fed into power lines, it is indistinguishable fro m electricity from any other source. Individu al generating st ations owned b y a g i ven utility m a y us e different fuels. The elect ricity genera ted by these stations is “m ixed” in the transm ission

lines of that utilit y

. T h e uti lit y is interconnected with neighbori ng utilities (als o using various t ypes of fuel), to form regional grids, which th en interconnect to form a nati onal grid.

Co m putational m odels currently used to perform life- cy cle inventories of electri city in the United States

are based on the fuel m i x in regional grids or on a na ti onal average. In m a ny cases where an industr y is scattered througho ut the U n ited States, the fuel m i x for the nationa l grid (available from the U.S.



### 32Depart ment of Energy ) can be used, m a k i ng calculations easier with out sacrificing accuracy

. Data for

2004 are shown in Table 3

- 1.

Table 3-1. U

. S. National Electrical Grid Fuel Mix f o r 2004

Fuel Gigawatt-hours (GWh) Percent

C o a l 1

, 9 7 6,33 3 5 0

N u c l e a r 7 8 8

, 556 19.9 Hy dr o 2 6 1

, 545 6.6

Natural Gas 714, 600 18.1

O i l 1 1 7

, 591 3

B i o m a s s 6 0

, 0 4 2 1 .5

O t h e r * 3 4

, 7 4 1 0 .9

T o t a l 3

, 9 5 3,40 8 100

Sou r ce: Ed iso n Electric In stitu te,
h ttp :// www.eei .org/industry_i ssues/industry _o v e rv iew_ and

_ s tatistics/in du stry_ s tatis

t i c s/ i ndex. ht m # f

u el m i x * Incl udes ge ot herm al , sol a r a n d wi nd p o w er

.

One exception to the national grid assum p tion is the electroprocess industries which use vast am ounts of electricity . Alum inu m s m e lting is the pri m ary exam pl e. It and the other electroprocessing industries are

not distrib u ted nationall y, so a national electricity gri d does not gi ve a reasonab l e approxim a tion of t h eir electricity use. The y are usually located in regions of i n expensive electric power. Som e plants have purchased their own electric utilities. In recognition of this fact, specific regional grids or data fromonsite facilities are co mmonly used for life

- cy cle inventories of the electroprocessi ng industries.

The energy efficiency of the electri city -generating a nd delivery s y ste m m u st also be considered. The

theoretical conversion fro m the co mm o n energ y u n it of kilowatt-h our to common fuel u n its ( m egajoules) is 3.61 MJ pe r kWh. Ideally, the analy s t would co m pute a specific e fficiency based on the electrical generation fu el m i x actually used. This value is de rived by com p ar ing the actual fuels consumed by the electricity -generating ind u s try i n the ap propriate regi onal or natio n a l grid to t h e actual kilowatt-hours of electricity delivered for useful work . The value includes boiler ineffici encies and transm i ssio n line losses. However, a conversion of 11.3 MJ per kWh m a y be used in m o st cases to reflect the actual use of fuel to

deliver electri city to the consumer fro m the national grid.

Nuclear Power: Nuclear power substitutes for fossil fuels in the ge neration of el ectricity . The r e is no measurement of nuclear po wer directly equivalent to t h e joules of f o ssil fuel, so nuclear power t y picall y is

mea s ured as i t s fossil fuel equivalenc y

. The preco m bustion energ y of nuclear po wer is usually added to the fuel equivalency value. The precom b ustion ener gy includes that for m i ning and processing, as well a s the increased energy require m en t for power plant shielding.

Hydropower: Most resear chers traditionally have counte d hydropower at its theoretical energ y equivalence of 3.61 MJ per kWh, with n o precom bus tion im pacts included. No preco m bustion factors are used for hydropower because wat e r does not have an i nherent energy value from which line transm ission losses, etc., can be subtracted. The contr i bution of t h e capital equipment is small in light of t h e am ount of

h y droelectric energy generated using the equipm ent. Disruption to ecosy stem s typically has no t been

considered in the inventor y. However, quantita tive inventor y m e asures that m a y be suitable for

characte r izing related issues, such as ha bitat loss due to land use co nversion, p o t e ntially co uld be

included. Fa ctors addressi ng area dam a ge, recovery t i m e , and ecosy stem function are under consideration

for inclusion in the im pact analy s is.



### 33Water Water volume requirem e nts should be i n cluded in a lif e-cy cle inven t or y anal y s is. In som e locations, water is plent i ful. Along the coasts, se a w ater is usabl e for cooling or other m a n u facturing purposes. However, in other places water is in short suppl y and m u st be all o cated for specific uses. Some areas

have abundan t water in some y ears and lim ited suppli es in other y ears. Some industrial appli cations reuse water with little new or makeup water required. In ot her applications, howev er, trem endous am ounts of

new water in puts are required.

How should water be incorporated in an inventor y? The goal of t h e inventor y i s to measure, per unit of product, t h e gallons of water required that represen t water unavail able for beneficial uses (su c h as navigation, a quatic habitat, and drinking water). Wat e r withdrawn from a strea m , used in a process, treated, and replaced in essentially the same quality and in the sam e location should not be included in the

water-use inventor y data. I d eally , water withdraw n from groundwater and subsequentl y discharged to a

surface water body shoul d be included, because the groundwat er is not replaced to m a intain it s beneficial purposes. Data to make this distinction may be diffi c u lt to obtain in a generic study where site-specific

inform ation is not available.

In practice, the water quantity to be estimated is net consum ptive usage. Consum ptive usage as a lifecy cle invent ory input is the fraction of total wate r with drawal fro m surface or groundwater sources that either is incorporated into t h e product, c o -prod u cts (if any ) , or wastes, or is evaporated. As in the general case of renewable versus nonrenewable resources, val u ati on of t h e degree to which the water i s or is not replenishable is best left to the im pa ct as sess ment.

Outputs of t h e Product Lif e -Cycle Inven tory Analysis

A traditional inventor y qua lifies three categories of environm ental r e leas es or e m issions: at m o spheric

em issions, waterborne waste, and solid waste. Produc ts and co-products also are quantified. Each of

these are as is discussed in m o r e deta il in the following sections. Most inventories consider environm enta l

releas es to be actual discha r ges (after co ntrol devices) of pollutants or other m a te rials fro m a p r ocess or operation under evaluation. Inventor y practice historic ally has include d only regulated e m is sions for each process becau se of data availability lim itations. It is reco mmended that analy s ts collect and report all available data in the detailed tabulation of subsy s tem outputs. I n a stud y not i n ten d ed for pr odu ct

co m p arisons, all of these pollutants should be included in the summary presentations.

A co m p arativ e study offers two options. The first is to include in the summary presentation only data

available for alternatives under consideration. The ad va ntage of thi s option is th at it gives a com p arable presentation of the loadings fro m all the alternatives. The disadvantage is that potentially consequential

inform ation, which is available only for so m e of the a lternatives, may not be used. The second option is to report all d a ta whether uniform ly available or not. In using t h is option, the analy s t should c a ution the

user not to dr aw any concl u sions about relative e ffects for pollutan t s where co mparable data are not

available. “C om par a ble” is used here to mean the sa me pollutant. F o r exam ple, in a summary of data on a bleached paper versus plastic packaging alternatives, data on dioxin em i ssions may be available only for the paper pro duct. The second optio n is reco mmended for internal studies and fo r external studies where
proper contex t can be provi ded.

At m o spheric E m issions

At m o spheric e m is sions are reported in units of wei ght and include a ll substance c l assified as p o llutants per unit weight of pr oduct output . Thes e em issions generally have included onl y those subst a nces required by r e gulator y agencies to be monitored but s hould be expanded where feasible. The am ounts reported represent actual d i scharges into the at m o sphe re after pas s i ng through existing em i ssion control

devices. Some em issions, such as fugitive em issions from valves or storage areas, may not pass through

control devic es before release to the environm en t. At m o spheric emissions from the production and



### 34co m bustion of fuel for proc ess or transportation en ergy (fuel-related e m is sions), as well as the process

e m is sions, are included in the life-cy cle inventory.

Typical atm o spheric em issions are particulates, nitrogen oxi des, volatile organi c co m pounds (VOCs),

sulfur oxi des, carbon m onoxide, aldeh y d es, ammonia, and l ead. Thi s list is neither all-inclusive nor is it a standard listing of which e m issions should be incl u d e d in the life- cy cle invent o r y

. Recommended practice is to obtain and re port em is sions data in the m o st speciat e d form possible. Som e air e m is sions, such as particulates and VOCs, are co mposites of m u ltiple material s whose speci fic m a keup can vary

from process to process. All em issions f o r which th er e are obtainable data shoul d be included in the

inventor y. T h erefore, the specific emissions reporte d for any s y st em , subsy s tem

, or process will vary depending on the range of regulated and nonregu l ated chem icals.

Certain m a t e r i als, such as carbon di oxide and water va por losses due to evaporation (neither of which is a regulated at mospheric e m is sion for m o st processe s), ha ve not been included in m o st inventory studies in the past. Regulations for c a rbon di oxide are cha nging as the debate surroundi ng the greenhous e effect and global climate ch ange continues and the m odels u sed for its prediction are modified. I n clusion of

these e m erging em i ssions of concern is reco mmended.

Waterborne Wastes

Waterborne waste s are r e ported in units of weight and include all substances generally regarded as pollutants per unit of product output. These w aste s t ypically have included only those ite m s re quired by regulator y ag encies, but th e list should be expanded as data are available. The effluent values include

those am ounts still present in the waste stream after wastewater treat m e nt, and represent actual discharges into receiving waters. For so m e rel eases, such as spills directly into receiving waters, treat men t devices

do n o t pla y a role in what i s reported. F o r some m a t e rials, such as brine water e x tracted with crude oil and reinjected into the for m ation, current U.S. re gula tions do not d e fine such m a terials as waterborne wastes, although t h e y m a y be considered in soli d waste regulations under the Resource Conservation and Recovery Act (RCRA). Ot her liquid wa stes may also be deep well injected and should be incl uded. In general, the broader definition of em issions in a life- cy cle in ventor y, in co ntrast to regulations , would

favor inclusion of such strea m s. It can b e argued, from a sy ste m s a n aly s is standpoint, that m a terials such

as brine shoul d count as releases fro m the subsy s te m because they cross the subsy s tem bounda ry . If wastes and spills that occur are discharged to the ocean or som e other body of water, these values are alway s reported as wa stes.

As with at m o spheric wast e s , waterborne waste s fro m the prod uctio n and com bustion of f u els (fuel-related

e m is sions), as well as proc ess e m issions , are included in the life-c y cle inventory

.

Some of the m o st co mm o n l y reported waterborne wastes are biological ox ygen dem a nd (BOD), chem ical

oxy g en dema nd (COD), suspended solids, dissolved so lids, oil and grease, sulfides, iron, chromiu m , tin, metal ions, cyanide, fluorid es, phenol, p h o sphates, and amm onia. Again, this listi ng of em issio n s is not

meant to be a standard for what should be included i n an invent or y. Som e waterborne wastes, such as BOD and COD, consist of m u ltiple materials who se com position can vary from process to process.
Actual wat e r borne wastes will vary f o r each sy stem de pending on the range of regulated and nonregulated

che m ic als.

Solid Waste

Solid waste includes all solid m a t e rial t h at is di sposed from all sources within the sy stem . U. S. regulations include certain liquids and gases in the de finition as well. Solid wastes ty pically a r e reported

b y weight. A distinction is made in data summa ries b e tween industrial solid wastes and post-consum er solid wastes, as they are generally dispos ed of in differe nt way s and, in som e cases, at different facilities.

Industrial sol i d waste refers to the solid waste generated durin g the productio n of a product an d its



### 35packaging and is ty pically divided into two categorie s : process solid waste and fuel-related so lid waste.

Post-consumer solid waste refers to the product/pack aging o n ce it has m e t its in tended use and is

discarded into the m unicipal solid waste strea m

.

Process solid waste is the waste gener a t e d in the actual process, su ch as tri m or waste mat e ria l s that are
not recy cled, as well a s sludges and solids from e m is sions control devices. Fuel-related waste is solid waste produced from the p r oduction and com bustion of fu els for tr ansportation and operating the process.

Fuel com bust i on residues, mineral extraction wast es, and solids from utility air control devices are

exa m ples of f u el-related w astes.

In the United States, m i ne tailings and o v erburden ge ne rally are not regulated as solid waste. However, the regulations require overburden to be replaced in the general area from which it was re m oved

. Furtherm ore, environm ental consequences associated with the rem oval of m i ne tailings and overburden

should be included. T h e regulations d o not require in dustrial solid waste to be handled off sit e

. Therefore, research ers try to report all s o lid waste fro m industrial processes desti n ed for disposal, whether

off site or local. Historical ly, no distinct ions have been m a de bet w een h azardous and nonhazardous solid waste, nor have individual waste s been s p ecifically ch aracte r ized. However, in view of the potentially

different environm ental ef f ects, analy s ts will find it us eful to account for these wastes separat ely, especially if an im pact assessment is to b e conducted.

Products The products are defined by the subs y s t e m and/or sy s t em under evaluation. In other words, each subsy s tem will have a resulting pr oduct, with respect to the entire sy stem . This subs y s tem product m a y be considered either a raw materi al or inter m ediat e material with re spect to another sy stem , or the finished product of the s y ste m

.

Again using the bar soap exa m ple, whe n exam ining th e meat pack aging subs y s te m
, meat, tall ow, hides,

and blo od wo uld all be con s idered produ ct outputs. Ho wever, because onl y tallo w is used in the bar soap

sy stem , tallo w is considered the onl y pr oduct from th at subsy s tem

. All other m a terial outputs (not

releas ed as w astes or e m iss i ons) are considered co-pro ducts. If the life-cy c le asse ss ment were performed

on a pro duct such as a leather purse, hid es would be considered the product fr om the meat packaging subsy s tem

, and all ot her o u tputs woul d be considered co-products.

Although for bar soap the tallow is considered the pro duct from the meat packaging subs y s tem, it is

si m u ltaneously an interm ed iate m a t e rial within the bar soap sy stem

. Thus, from these exa m pl e s one can see that classi fy i ng a m a ter i al as a product in a life- cycle study depends, in part, on the extent of the

sy stem being exa m ined, i.e., the position from which t h e ma terial i s viewed or the analy s t’ s point of view.

Transportation The life-cy cle inventory inc l udes the energy requirem e nts and em issions generate d b y t h e transportation requirem e nts am ong subs ystems for bot h distributi o n a nd disposal of wastes. Transportation data are reported in miles or kilom e ters shipped. This distan ce is then conve rted into u n its of ton-m iles or ton n ekilom e ters, which is an expression invol ving t h e wei ght of the shi p ment and the distance shipped. Materials ty pically are transported by rail, truck, barg e
, pipeline, and ocean transport. The efficiency of

each m ode of transport is used to conver t the units of t on-m iles into fuel units (e.g., gallons of diesel fuel).

The fuel units are then converted to energ y u n its, and calculations are m a de to determ ine the emissions generated from the co m bustion of the f u els.

Exhibit 3-2 s hows that transportation is evaluated fo r the product l eaving each subs y s tem

. This method of evaluating transportation avoids an y i n advertent dou ble-counting of transportation energ y or em issions. Transportation is reported onl y f o r the p r oduct of i n te rest fro m a su bsy s tem and not for an y co -products



### 36of the subs y s te m
, becaus e t h e destina tion of the co-products is not a n i ssue. The raw material s for the bar soap producti on s y stem , fo r exam ple, include salt from salt m i ning and trees from natural for est harvesting. Apply i ng the te m p late to these two s ubsyste ms shows t h at the transport of salt from the mining operat i on and t h e tr ansport of tre es fro m the logging operati on m u st be included in the data collected for these subsy s tems.

The salt is transported to c h lorine /sodium hy droxide plants , and the trees are transported to pulp m ills. Appl y i ng the tem p late to these subsy s tems shows th at the transport of chlorine a nd sodi um hydroxide

from those plants to pul p mills is part of the ch lorine production and sodium hydroxide subs y s tem s

. Likewise, the transport of pulp t o paper mills is part of the pulp m i l l subs y s tem

. The transport of raw

materi als, salt

, and trees into the subs y s t e m s ( c hl orine producti on, s odium hydroxide producti on, and pul p mills) now being evaluated has already been accounted for in the evaluation of t h e salt m i ning and natural forest harvesting subs y s te ms. Apply i n g the tem p late throug hout the bar soap sy stem shows the

evaluation of transportation ending with t h e post-c onsumer w aste ma nage m e nt subsy s tem

, wher e wast es

may be transported to a fi nal disposal site.

Backhauling may be a situation where there is so m e overlap between the transportation associated with product distribution and t h e transportation associated with recy cling of the produc t or a different product

after consu m er use. A bac khaul has been describ ed as occurring when a truck or rail carrier h as a profitable loa d in one direction and is willing to accep t a reduced rate for a m ove in the return direction. Backhaul opp ortunities occur when the d e m a nd for frei ght transport a tion in one area is relatively low and

carrier s have a financial incentive to m o ve their vehi cles, loaded or e m pty

, to a place wher e the de m a nd for freight tra n sportation is higher. Due to the lowere d transportation rates, recycled m a teri als

, especially paper and alu m inum , are often transpor ted b y backha uling. Thus, a carri er may take a load of new paper

from a m ill to customers in a m e tropolitan area and pick up l o ads of scrap paper in the sam e area to bring

them back to the m ill. In this scenario, backhauli ng may reduce the energy and em i ssions associated wit h distribution of a product ( m ade fro m new paper) by assigning ener gy and em issi ons associated with an

e m pty return trip to the recy cled scrap paper.

Co-Product Allocation

Most industri a l processes are phy s ical and/or chem ical processes. T h e fundam e nt als of life-cy cle inventory are based on m odeling a sy ste m in such a w a y that calculated values re asonably represent actual ( m easurable) occurrences. Some pr ocesses generate multiple output streams in additi on to waste streams. In attributional LCAs, only certain of these output strea m s are of i n terest with respect to the primary product being evaluated (see the text box in Chap ter 2 on the disti n ction between attributional a nd consequential LCAs). The term co-product is used to define all out put stream s o t her than the primary product t h at are not waste streams and that are not used as raw materials el sewhere in the s y stem

exam ined in the inventor y. Co-products are of inter est onl y t o the p o int where th ey n o lo nger affect the primary pro d u ct, i.e. the pr oduct that is part of the lif e cy cle sy ste m being studied. Subseque nt refining of co-products i s bey o nd t h e scope of the analy s is, as is t r ansport of co-products to f acilities for further refining. A b asis for co-product allocation needs to b e selected with careful attention paid to the specific

ite m s c a lculat ed. Each industrial sy stem m u st be handled on a case- by -case basis since no allocation basis exists that is alway s a pplicable.



### 37Exhibit 3-3. Allocating Resource s and Environm e n tal Burdens on a Mass Basis for a Product and Co-Product (Source: EPA 1993)

Co-Product Allocation for Product “A” and Product “B”

Co-Product Allocation for Product “A”

Co-Product Allocation for Product “B”



### 38In effect, the boun dar y for the analy s is i s drawn be tween the primary prod uct an d co-prod u cts, with all

materials and environm ental loadings attributed to co -products bei ng o u tside th e scope of the analy s is.

For exam ple, the prod uctio n of fatt y acid s fro m ta llow for soap m a n u facture generates gly cerine, a secondary str e am that is co llected and sold. Gl y cerin e, therefore, is considered a co-product, a nd its processing and use would be outside the scope of the bar soap analy s is.

Basis for Co-Product Alloc a tion The first step is to investiga t e any com p lex process in detail and atte m p t to identify unit subprocesse s that produce the product of i n terest. If sufficient detail can be found, no co-product allocation will be

necessary

. T h e series of subprocesses t h at produce the product ca n sim p ly be summed. Many m e t a l manufacturing plants illust rate this approach. In steel product m a nufacture, all products are made by melting the raw m a terials, producing iron, and t h en pr oducing raw steel. These steps are foll owed by a series of finishing operations that are unique to each pr oduct line. I t is generally possible to identify the particular subprocesses in the finishing s e quence of each product and to collect sufficient data to carry out the life-cy cle inventor y without co- p roduct allocation. In m a ny cases, a car eful analy s is of uni t sy stem s will avoid the need to m a ke co-product al locations. Sti ll, in som e cases, such as a single chem ical reaction vessel that produc es several different pr oduc ts, there is no analy tical m e thod f o r cleanly separating the subprocesses. In this exa m pl e, co-product allocation is necessary

.

The analy s t needs to determine the spec ific resource and environm ental categories requiring stud y

. For a given pr oduct

, different co-product alloc a tions may be made for diffe rent resource and environ m ental categories. To find t h e raw materials needed to pr oduc e a product, a sim p le m a ss balance will help track

the various in put m a terials into the outp u t materials. For instance, if a certain amount of wood is needed to produce several paper products, and t h e analy s is concerns onl y one of the products, then a mass

allocation schem e, as dem o nstrated in Ex hibit 3- 3, w ill be used to de term ine the am ount of wood required for the target product.

If a process produces sever al different chem ical products, care m u st be taken in the analy s is. It will be

necess ary to write balance d chem i cal eq uations and trace the che m i cal stoichio metry from the raw

materi als into the products. A si m p le mass alloca tion method frequentl y gi ves reasonable results, but not alway s . In calculating energy , heat of re action may be the appropriate basis for a llocating energy to the various co-pr oducts.

If the various co-product ch em icals are quite different in nature, so me other allocation method m a y be

needed. For exam ple, an electroly tic cell can pr oduce h y dro g en an d ox ygen fro m water. Each water

m o lecule req u ires two electrons to pr od uce two h y dr ogen atom s and o n e ox ygen atom . On a macroscopic basis, electri c ity that produces one m o le (or two gr ams) of hy drogen only pro duc es one-half mole (or 16

gram s) of oxygen. T hus, t h e input electrical energy would be allo cated between the h ydroge n and o x y gen co-products o n a m o lar basis. That is, t w o-thirds of t h e energy would be allocated to the h ydr ogen and

one-third t o t h e oxy g en, resulting in an energy per unit mass for hydrogen t h at is 16 tim es that of oxygen.
However, co nservation of mass is used to determ ine the material requirements. Each m o le of water (18

gram s) contains two grams of h ydr ogen ato m s and 16 gram s of ox ygen atom s, an d the dissociation of t h e water results in two gram s of h y dr ogen a nd 1 6 gr am s of ox ygen. T hus, a m a ss allocation woul d be appropriate for raw m a terial calculations in this example.

For environm ental em issions from a m u l tiple-product pr ocess, allocation to different co-produc ts m a y not be possible. For exam ple, in a brine cell that pr oduces sodium , chl o rine, and hydrogen as co-products, it

may be tem p t i ng to associate any em issi ons containing chlorine wit h the chlorine co-product al one. However, because the sodium and hy dr o g en are also produced b y th e same cell and cannot be produced

from this cell without also producin g chl o rine, all em issions should be considered as joint wastes. The question arises as to how to allocate chlorine em ission s (as well as other em i ssio n s) to all thre e products.



### 39It has been suggested that the selling pri ce of the co-p roducts could be used as a basis for this allocation. Because the selling prices of the various co-products can vary greatly with tim e and with inde pendent

co m p etitive markets for each co-p roduct, a m a rket-b ased approach would have to acco mm o d ate such variations, b y using an aver age value range d over several y ears, or sim ilar method.

Further, it has been suggested that the no tion of ‘ d ema nd pro duct ’ c ould be used t o avoid alloc a tion. The idea is to recognize when a process was created with the intent of pr oducing a single main product of interest, i.e. the one in demand. By

- p r oducts and w astes that are created as a result of manufacturing this

dem a nd prod uct are considered to be incidental, incl u d ing t hose th at m a y have found a market over the

y ears. Therefore, all of the environm enta l burdens are allocated to the demand product.

One final issue is the distinction between marginal wa stes and co-products. In so me cases it is not clear

whether a m a terial is a wa s t e or a co-product. A h ypo thetical example m i ght be a valuable m i neral that occurs as 0.1 percent of an ore. For each pound of m i neral product, 999 pounds of unneeded materi al is produced. This discarded materi al m i ght find use as a ro ad aggregate. As such, it has value and displaces other commercial aggregates and appears to be a co-p r oduct alon g with the valu able m i neral. However,

its value is so low that in s o me ca ses it may sim p ly be dum ped bac k on the ground because of lim it ed

markets. Wh ether this m a t e rial is considered a wa st e or a co-product m a y have a significant effect on the results of a product life-c y cle inventor y

. It does not se em reasonable to use a si mple mass allocation

sche m e here. It is m o re r e a s onable to assume that all of the energy and other resources and e m i ssions

associat ed wi th this process are incu rred because of the desire for the valuable product m i neral

. However,

there are so me cas es wher e the “waste ” has m a rginal, but greater value than the exa m ple used here.

It becomes di fficult in some instances to deter m ine precisely which of the co-product allocation methodologie s discussed above is m o st “correct.” One im portant role of an inventor y is to pr ovide

inform ation upon which im pact assessment and im provem e nt analysis can be based. In cases where there

is no clear m e thodol ogical solution, the i nventor y shou ld include reasonable alter n ative calculations or appl y sensitivity anal y s is to determ ine the effect of al l o cation on t h e final results. It remains at some later

time to m a ke the judgm ents as to which of several reas onable alternatives is the correct one. In an y event,
it should be made cl ear what assu m p tions were made and what procedures wer e used.

Industrial Scrap One co-product strea m of particular interest is industrial scrap . This ter m is used to specificall y identify process wastes of value (trim scr aps and off-spec m a t e ri als) that are produced as an integral par t of a manufacturing process. Further, the wastes have been collected and used as input material s for additional manufacturing processes. The last criter i on is that the se scr ap m a te rials have never been used as originall y i n t e nded when manufactured . For exam pl e, a co mm on pol y u rethane foam product is seat

cushions for autom obiles. The trim fro m cutting the cu shions is never incorporated into seat cushions. Likewise, off-spec seat cushions sold as industrial scr ap are never used as seat cushions, but a r e used as input m a terial for another process.

A careful distinction m u st be made between i ndustrial scrap and po st-consu m er waste for proper

allocation in t h e inventor y. If the ind u strial scrap is to be collected and used as a material input to a productio n s y stem or process, it is credited in the life- cy cle invent o r y as a co-pro duct at the po int where it was produced. Unfortunate ly, s y stem s that use m a t e rial m o re efficientl y , i.e., that produce lesser am ounts of salable co-products, assume a higher percentage of the upstream energy and r e leases using the

criterion.

When the con s u m ption of a co-product f a lls within th e boundaries of the anal y s is, it m u st no longer be considered as a co-product, but as a primary pr oduc t c a rry in g with i t all the energy requirements and



### 40environm ental releases involved with pr oducing it, be ginning with raw materials acquisition. For

exam ple, a stud y of carpet underla y m e nt made fro m p o l y urethane scrap would in clude the manufacturing steps for prod ucing the p o l yurethane scrap. Its prod u c tion m u st be handled, as i s any other su bsy s tem of a life-cy cle inventory

. Industrial scrap does not di splace virgin raw m a te rials, because the c onsum ption

of the ind u strial scrap redefines the sy st em to incl ude the virgin m a terials for its productio n (is o cy anates and poly a lcohols in the case of poly u rethane foa m ). Ta llow is another exa m ple of a material t h at would

be defined as an industrial scrap/co-product. Historica lly

, the thin k i ng has been t h at once a material shifts

from the waste category to being a u tiliz ed material, o r a co-produc t, then it should bear some of the burden (energ y, raw/interm ediate m a terial input, an d environm en tal releases) for its own pro d u ction.

Data Ti me Period The time peri od that data r e presents sho u ld be long e nough to sm ooth out any deviations or variations in

the norm a l operations of a facility . These variati ons might include plant shutdowns for routine maintenance, startup activities, and fluctuation in leve ls of prod uction. Often dat a are available for a fiscal y ear of production, w h ich is usuall y a su fficient time period to cover such variations.

Specific Data versus Co m posite Data When the pur pose of the in ventor y is to f i nd way s t o i m prove internal operations, it is best to use data specific to the sy stem that is bei ng examined. These types of data are usually the m o st accurat e and also

the m o st help ful in anal y z i ng potential i m provements to the environmental profile of a sy stem. However, private data typically are guarded by a c onfidentialit y agreement, and m u st be protected from public use

b y som e means. Com posite, industr y

- av erage data ar e preferable when the inven t or y results are to be

used for broa d application across the industry, particul arly i n studie s perform ed for pub lic use. Althoug h

co m posite data m a y be less specific to a particular co m p any
, the y are generally m o r e repres e n tative of an

industr y as a whole. Such co m posite data can also be made publicly available, are m o re widely usable,

and are m o re general in nature. Com posite data can be generated from facility -specific data in a

sy stematic fashion and validated using a peer revi ew process. Vari ability

, representativeness, and other data qualit y i ndicators can still be specified for com p osite data.

Geographic Specificity

Natural resou r ce and environm ental con sequences oc cur at specifi c sites, but there are broad e r i m plications. It is im portant to de fine t h e scope of interest (regional vs . national vs. international) in an inventory. A local co mm u n ity m a y be m o r e interest ed in direct consequences to itself than in global

concerns.

In general, most inventorie s done dom estically relate onl y t o that c ountr y . However, if the analy s is

considers im ported oil, t h e oilfield brines generated in the Middle E ast should be considered. It has been suggested that the results of life-cy cle inventories indicate which en ergy requirements and environm ental releases (of the total envir onm ental profile of a prod uct) are local. However, due to the fact that

industries are not evenl y di stributed, this seg m e n ting can be done o n l y after an acceptable level of

accura cy is agreed on. The United States, Canada, Western Europe, and Japan have the m o s t accurate
and m o st re a d ily available inform ation on resource use and environmental relea ses. Global a s pects
should be con s idered when perform ing a stud y o n a s y stem that includes foreign countries or p r oducts, or

when the diff erent geographic locations are a key diff erence among products or processes being

co m p ared. A s a co m p ro m i se, when no specific geogra phical data e x ist, practices that occur in other

countries t y pi cally are assumed to be the same as fo r their dom esti c counterparts. These assu m p tions and

the inherent li mitations associated with their application should be docum ented within the inventor y report. In view of the m o re stringent environm enta l re gulations in developed countries, this assu m p tion,

while neces sa ry , often is not correct. Energy u se and other consequences a ssocia t ed with im porting

materials should also be in cluded.



### 41Technolog y Mixes/Energy T y pes For invent or y studies of pr ocesses using various technology m i xes, market shar e distribution of the technologies may be necessary to accurately portra y c onditi ons for the industr y a s a whole. The same is true of energy sources. Most inventorie s can be base d on data involving the fue l m i x in the national grid for electricity. There are exceptions, such as th e aluminum electr oprocessing i ndustr y previ ousl y discussed. Variations of this kind m u st be taken into account when appl y i ng the life-cy cle inventor y methodolog y. Also, as previousl y m e ntioned, con d iti ons can differ greatly acros s international borders.

Data Categories

Environm ental em ission d a tabases usually cover onl y those items or pollutants re quired b y reg u lator y agencies to be reported. For exa m ple, a s previously mentioned, th e question of whether to report o n l y regulated e m i ssions or all emissions is c o m p lic ated by the difficult y in o b tainin g data for unre gulated

e m is sions. In some ca ses, e m is sions that are suspecte d health hazards may not be required to be reported by a regulatory agency because the process of adding the m to the list is slow. A specific exa m ple of an unregulated emission is carbon dioxi de, which is a gr eenhouse gas suspected as a pr imary agent in glo b al

warm ing. There is no current requirement for repor ti ng carbon dio x ide em issions, and it is dif f icult to

obtain m e asured data on the am ounts rel eased fro m v a rious processes. Thus, results for em issions reported in a l i fe-cy c le inventor y m a y no t be viewed as co m p rehensive, but t h e y can cover a wide range of poll u tants. As a rule, it is reco mmend ed that data b e obtained on as broad a range as possible. Calculated or qualitative informati on, although less desirable and less consistent with the quantitative

nature of an i nventor y, m a y still be useful.

Routine/Fugit i ve/Accidental Releases Whenever possible, routine, fugitive, and accidental emissions data should be considered in developing data for a subsy s tem

. If da ta on fugitive and accide nta l e m issions ar e not available, and quantitative

estimates cannot be o b tain ed, this deficiency sho u ld b e noted in t h e report on the inventor y results. Often

esti m ates c a n be made for accidental e m issions based on historical data pertaining to frequenc y and

concentrations of accidental em issions experienced at a facility

.

When deciding whether to include accide nts, the y should be divided into two categories based on frequency

. For the low-frequenc y and high-m a gnitude ev ents, e.g., major oil spills, tools othe r than lifecy cle inventory m a y be appropriate . Unusual circu m s t ances ar e difficult to associate with a particular product or activit y

. M o re frequent, lower magnitude events should be included, with perhaps so m e justification for keeping t h eir contributi on separate from routine operations.

Special Case Boundar y Issues In all studies, boundary conditions lim it ing the sc ope m u st be estab lished. The areas of capital equipm ent, personnel issues, and im pro p er waste dispo sal t y pically are not incl uded in i nven t or y studies, because they have been shown to have little effect on the results. Earlier studies did consider them in the analy s is; later studies have verified their mini m a l cont ribution to t h e total sy stem profile. Thus, exclusion

of contrib u tio ns from capital equipm ent ma nufacture, for exam ple, is not exclude d a priori

. The decision

to include or not to include them should be clearly not ed b y the anal y s t.

Capital Equi pment - The energy and resources that are required to construct buildings and to build process equipment should be considered. However, fo r m o st sy stems, capital ex penditures are allocated to a large nu m b er of prod ucts m a nufactured durin g t h e lifeti m e of the equipm e n t. Therefore, the resource

use and envir onm ental effluents produce d are usually sm a ll when attributed to th e sy stem of interest. The

energy an d emissions involved with capital equipm en t can be excluded when the manufacture of the item

itself account s for a m i nor fraction of th e total produc t outp u t o v er the life of the equipm ent.



### 42Personnel Issues - Inventor y studies focu s on the com p rehens ive results of pro duc t consum ption,

includin g m a nufacturing. At any given site, there are personnel-related efflue nts from the manufacturing

process as well as wast es fr om lunchroom tr ash, ener gy use, air conditioning e m issions, wat e r pollution

from sanitary facilities, an d others. In a ddition, input s and outputs during tr ansportation of personnel

from their re s i dence to the workplace ca n be signi ficant, depending on the purpose and scope of the inventory. In many s ituations, the personnel consequences ar e ver y small and would probably occur

whether or no t the prod uct was manufactured. Therefor e, exclusion from the inventor y m a y be justified. The analy s t s hould be expl icit about incl uding or excl uding this categor y

. For these issues, the goals of the study should be considered. If the study is com p arative, and on e option is significantl y di fferent in personnel or capital equipment requirements, then at least a screen ing-level evaluation should be performed to support an i n clusion or ex clusion decision.

Improper W a ste Disposal - For m o st stu d ies it is assu med that wast es are properl y disposed into the

m unicipal sol i d waste stream or wastewater treat ment sy stem . Illeg a l dum ping, littering, and other

im proper waste disposal methods t y pical ly are not con s idered in life-cy cle invent ories as a means of solid waste disposal. Where im p r oper disposal is known t o occur and where environmental effects are known or suspected, a case m a y be ma de to include these acti v ities.

Economic In put/Output Approac h to Life Cycle Inventory

Econom ic In put/Outpu t of fers an altern ative way to c r eate life cy cle inventor y

. The input/ out put

m odel divides an entire econom y int o distinct sectors and represents them in table, or m a trix, form

so that each s ector is repre sented by one row a nd one colum n . The matrix repres ents sales fro m one sector to another. Most nat i ons have created input/out put tables although few are as detailed as the

U.S. m odel which provides 480 sectors. The econom i c input-output m odel is linear so that the effects of purchasing $1,000 from one sector will be ten tim es great er than the effects of purchasing $100 from that sector.

In order to create life cy cle inventory, the econo m i c output for each sector is first calculated, then

the environm ental outputs are cal culated by m u ltip ly ing the economic output at each stage by the

environm ental im pact per dollar of out pu t. The a dvant age of the econom ic input/output approa ch is that it quickly covers an entire econo m y , including all the material a nd energy inputs, thereby

si m p lify i ng the inventory creation process. Its main disadvantage is that the data are cr eated at high aggregate levels for an entire industr y , s u ch as st eel mills, rather than particular products, suc h as the ty pe of steel used to make autom obi les.

“Hy b rid” m odels which com b ine the econom ic inpu t/output m odel with process m odels have also been propose d in or der to utilize the a dvantages offered by both a pproaches. (Hendrickson et al 20 06)



### 43Step 4: Evaluate and Document the LCI Results When writing a report to present the final results of the life-cy cle inventory

, it is im portant to thoroughly describe the methodology used in the analy s is. The r e port shoul d explicitl y defi ne the sy stems analy zed

and the boundaries that we re set. All as su m p tions made in performing the inve ntor y sh ould be clearly explained. T h e basis for com p arison am ong sy stems shoul d be gi ven, and an y equivalent us age ratios that

were used sh ould be explained.

Life-cy c le inventor y stu d i es generate a great deal of inform ation, often of a disparate nature. The analy s t
needs to selec t a presentati on form at an d content that ar e consisten t with the purpose of the study and that do not arbitrarily sim p lify t h e inform atio n solel y fo r the sake of pres enting it. In th in k i ng ab ou t presentation of the results, it is useful to identif y t h e various perspectives em bodied in life-cy cl e inventor y inform ation. These di m e ns ions include, but m a y not be li m ited to, the following:

• Overall product sy stem

• Relative contribution of stages to the overall sy ste m

• Relative contribution of pr oduct com ponents to the o v erall sy stem

• Data c a tegories within and across st ages, e.g., resource use, energy consum ption, and

environm enta l releas es

• Data parameter groups wit h in a category, e.g ., air emissions, waterborne wastes, and solid
waste ty pes

• Data parameters within a group, e.g ., su l f ur oxides, carbon d i oxi de, chlorine, etc.

• Geographic regionalization if relevant t o the stud y, e. g., natio nal v e rsus global

• Te m poral cha nges.

The life-cy cle analy s t m u st select am ong these di m e nsi ons and devel op a presentation form at that

increases co m p r e hension of the findi ngs without ove rsi m plify i ng t h em . Two main t y pes of f o rmat for presenting results are tabular and graphical.

Someti m e s it is useful to report total ene r gy results while also breaking out t h e contribut ions t o the total

from proce ss energy and energy of m a te rial resources . Solid waste s can be separ ated into postconsumer

solid waste and in dustrial solid waste. Individ u al atmospheric and water po llutants should be reported separately

. At m o spheric e m issions, wat e rborne waste s , and industrial solid wastes can also be categorized by process e m i ssions/wast es and fuel-rela ted e m issions /waste s . Such item i zed presentations

can assi st in identify i ng and subsequently contro lling certain energ y consum ption and environmental

releas es.

The results from the inventory can be presented m o st co m p rehensi b ly in tabular form . The ch oice of how the tables should be created varies, based on t h e pur p o se and scope of the stud y. If the invent or y has been performed to help decide which t y pe of p ackage to use for a particular product, sh owing the o v e rall

sy stem results will be the m o st useful way to present the data. On the other hand, when an a n aly s is is performed to deter m ine how a package can be change d to reduce its relea ses to the environm ent, it is

i m portant to present not onl y the overall results, but also the contributions made by each com ponent of the packaging sy stem . For exam ple, in analy z ing a liquid delivery s y stem that uses plastic bottles, it m a y be necessary to show how the bottle, the cap, the label, the corrugated shipping box, and the stretch wrap

around t h e bo xes all contribute to t h e tot a l results. Th e user can thus concentrate im provem e nt efforts on

the com ponents that m a k e a substantial cont ributi on when evaluating pro posed changes.

Graphical presentation of i n form ation helps to augm ent tabular dat a and can aid in interpretation. Bot h bar charts (either indivi dual bars or stacked bars) and pie charts are valuable in helping the reader

visualize and assi milate the inform ation from the pers p ective of “gaining owners hip or participation in life-cy cle assessment” (Werner 1991). However, the analy s t sho u l d not ag gregate or sum dissim ilar data

when creatin g or sim p lify i ng a graph.



### 44For internal i ndustrial use b y pro duct manufacturers, pie charts showing a breakout b y raw materials, process, and use/disposal have been found useful in identif y i ng waste reduction opportunities

.

For external studies, the dat a m u st be presented in a form at that m eets one funda mental criterion - clarit y

. Ensuring clarity requires that the analy s t ask and answ er questions about what each graph is i n t e nded to

conve y

. It m a y be necessary to present a larger num b e r of graphs and incor porate fewer dat a in each one.

Each reader should un derstand the desired response after viewing th e information.

Now that the data has been collected and organized into one form at or another, the accura cy of the results

m u st be verified. The accuracy m u st be suffici ent to support the purposes for perform ing the LCA as

defined in the goal and scope (see Chap t e r 2 for a discussion on goa l definition).

Steps 1 and 2 of Chapter 5, Life Cy cle Interpretati on, describe how to efficiently asse ss the ac c u racy of

the LCI results. As illustrated in Exhibit 1-2, Ph ases of an LCA, in Chapter 1, LCA is an iterative process. Det e r m ining the sensitivity of the LCI data co llection efforts in regard to data accuracy prior to conducting the saves ti me and resources. Otherwise, t h e life cy cle i m p act assessment effort may have t o be repeated if it is later deter m ined that the accur acy of the data is insufficient to draw conclusions.

When documenting the results of the life cy cle invent or y , it is im portant to t hor oughl y describe the methodolog y used in the an aly s is, define the sy stem s analy zed and t h e boun daries that were set, and all

assu m p tions made in perfor m ing the inventor y anal y s is . Use of the worksheet (see Step 2) supports a clear process for docum enting this i n for m ation.

The outcom e of the inventory analy s is is a list cont aining the quantities of polluta nts releas ed to the

environm ent and the am ou nt of energ y a nd m a terial s consumed. The inform atio n can be orga nized b y life cy cle stage, m e dia (air, water, and la nd), speci fic process, or any com b ination thereof that is consistent with the gro und rules defined in Chap ter 2, Goal Definition and Sco p i ng, for rep o rti ng requirem e nts.



### 45Chapter 4 Life Cycle I m pact As ses sment

What is a Life Cycle I m p a ct Asse ss me nt (LCIA)? The Life Cy c l e I m pact A s s ess ment (LCI A) phase of an LCA is the evaluation of potential hum an health

and environm ental i m pacts of the environmental reso urces and rele ases identifie d during the LCI. Im pa ct assessment should address ecological and hum an heal th e ffects; it should also address resource depletion. A life cy cle im p act assessment a ttem p t s to establish a linkage between the product or pr ocess and its potential envi ronm ental impacts. For exam ple, what are the im pacts of 9,00 0 to n s of carbon di oxide or 5,000 tons of methane e m is sions releas ed into the at m o sphere? Which is worse? What are their potential

im pacts on sm og? On glo b al warm ing?

LCA ver s us Risk As ses s m ent

An im portant distinction e x ists between life cy cl e impact ass ess me nt (LCIA) and other types of

i m pact analy s is. LCIA does not necessar ily atte m p t to quantify any specific a c tua l im pa cts
associat ed wi th a product, process, or ac tivity

. Instead, it seeks to establish a linkage between a

sy stem and potential im pa cts. The m odels used within LCIA are often derived and sim p lified versions of more sophisticated m odels within each of t h e various impact categories. These si mplified

m odel s are su itable for relative com p ari s ons of the pot e ntial to cause hum an or environm ental

dam a ge, but are not indicat ors of absolut e risk or act ual dam a ge to hum an health or the enviro nment.
For exam ple, risk asse ss me nts are often very narrowl y focused on a single che m ical at a very specific

location. In t h e case of a tr aditional risk assessme nt, it is possible to conduct ver y detailed m o d e ling of the predict e d im pacts of the chem ical on the p opula tion exposed and even to predict the probabilit y of the populat ion being im pacted by t h e emission. In t h e case of LCIA, hundreds of chem ical

e m is sions (and resource str essors) which are occurri ng at various locations are ev aluated for their potential im pacts in m u ltiple i m pact categories. Th e sheer num ber of stressors being evaluated, the variety of loc a tions, and th e diversity of im p act categories m a k es it im possible to conduct the

assessment at the sam e lev e l of rigor as a traditi onal risk assessment. Instead, LCIA m odels are

based on the accepted m o d e ls within eac h of the im pact categories using assum p tions and default values as necessary

. The resulting m odels that ar e used within LC IA are suitabl e for relative

co m p arisons, but not sufficient for absolute predictions of risk.

The key conc ept in this com ponent is that of stressors . A stressor i s a set of conditions that m a y lead to

an im pact. For exam ple, if a product or pro cess is emitting greenhouse gases, the increase of greenhouse gases in the a t m o sphere may contribute to global warming. Processes that result in the discha r ge of

excess nutrients into bodie s of water ma y lead to eutrophication. An LCIA provides a sy stematic procedure for classify ing a nd characteri z i ng these types of environmental eff ect s.

Why Conduct an LCIA?

Although m u ch can be lear ned about a process by cons idering the li fe cy cle inve ntor y data, an LCIA provides a more m eaningful basis to m a ke com p ariso n s. For example, althoug h we know that 9,00 0 to ns of carbon di o x ide and 5

, 00 0 tons of m e thane released into t h e atm o sphere are both harm ful, an LCIA can

deter m ine wh ich could have a greater potential im p act . Using science-bas e d characteriz ation factors, an

LCIA can c a lculate the i m pacts ea ch environm ental r e leas e has on problem s suc h as s m og or global

warm ing.



### 46Midpoint ve rsus Endpoi n t Modeling

Midpoin t im pact assessment m odels reflect the relative potenc y of th e stressors at a co mm on midpoint wit h in the cause-effect chain. Analy s is at a midpoint m i ni m i zes the amount of forecasting

and effect m o deling incorporated into the LCIA, thereb y reducing t h e com p lexity of the m odeling and often simplif y i ng comm unication. Midpoin t m o deling can m i nim i ze assu mptions and value choices, refle c t a higher level of societal consensus, and be m o re c o m p rehens iv e than m odel coverage for endpoi nt estimation. ( B are et al 2003)

What Do the Results of an LCIA Mea n ?

The results of an LCIA show the relative differences i n potential environm ental i m p acts for ea ch option.

For exam ple, an LCIA could determ ine which pr oduc t/process causes m o re global war m ing potential.

Key Steps of a Life Cycle Impact As se ssment The following steps co m p rise a lif e cy cle i m pact a sse ss ment.

1. Selection and Definition of Impact Categories - identif y i ng relevant environm ental i m p act categories (e.g., gl obal warming, acidification, terrestrial toxicit y ).

2. Classification - assigning LCI results t o the i m pact categories ( e

. g ., classify ing carbon dioxide

em issions to global warm ing).

3. Characterization - m odel i ng LCI im pacts within im pa ct cat egories using science-ba sed conversion factors (e.g., modeling t h e p o tential im pact of carbon dioxide an d methane on global

warm ing).

4. Normalization - expressing potential im p acts in w a y s that can be co m p ared ( e .g. com p arin g the global warm ing im pact of carbon diox id e and methane for the two options).



### 475. Grouping
- sorting or ra nking t h e in dicators (e.g. sorting the indicators b y location: lo cal, regional, and global).

6. Weighting - em pha sizing the m o st i m po rtant potential im pa cts.

7. Evaluatin g and Reporting LCIA Results - gaining a better understandi ng of the reliability of th e LCIA results.

ISO developed a standard for conducting an im pact assessment entitled ISO 14042, Life Cycle Impact

Asses sment (I SO 1998) , w h ich states that the first three steps – im p act cat egory selection, classifi cation,

and charact er ization – are mandatory steps for an L C IA. Exc e pt for data eval uation (Step 7), the other steps are optional dependi ng o n the g o al and scope of the stud y

.

Step 1: Select and Define Im p act Categories The first step in an LCIA is to select the im p act ca tegories that will be considered as part of the overall LCA. This step should be co m p leted as part of th e ini tial goal and s c ope definition phase to gui d e the LCI data collection process and requires reconsiderati on following the data collection phase. The ite m s identified in t h e LCI have potential hum an health and environm enta l im pa cts. For exa m ple, an

environm ental release identified in the L C I m a y harm hum an health by causing c a ncer or steril ity, or affect workplace s a fety . Likewise, a rel ease identifie d in the LCI c ould also affect the environment by causing acid rain, global w a rm ing, or endangering spe c ies of anim als.

For an LCIA, im pacts are defined as the consequences that could be caused by t h e input and o u tput streams of a sy stem on human health, plants, and animal s, or the future availability of natural resources. Typically, LCIAs focus on the potential im pa cts to three m a in cat egories: human health, ecological health, and resource depletion. E xhibit 4

- 1 shows some of the m o re co mm only us ed im pa ct cat egories.

Step 2: Classification The purpose of classific a tion is to organize and possibly com b ine the LCI results into im pact categories. For LCI items that contribute to only one i m pact c a te gory
, the proc edure is a stra ightforward assign m e nt.
For exam ple, carbon dioxide em issions can be classifi ed into t h e gl obal war m ing category

. For LCI items that contribute to two or m o re differe n t im pa ct cat e gories, a rule m u st be estab lished for

classifi cation. There are tw o way s of assigning LCI results to m u lti ple im pa ct ca tegories (ISO 1998):

• Partition a representative portion of the LCI results to the im pact categories to which the y contribute. This is ty pically allowed in case s when the effects are dependent on each other.

• Assign all LCI results to all im pa ct cat egories to which the y contri bute. This is t ypically allowed

when the effe cts are indepe ndent of each other.

For exam ple, since nitrogen dio x ide cou l d potentia ll y affect both gr ound level ozone form atio n and acidification (at the sa me time), the entire quantity of nitrogen dioxide would be assigned to both im pact categories (e.g., 1 00 percent to gr oun d l e vel ozone and 10 0 percent to aci dification). Th is pro cedure m u st be clearly docu m e nted.



### 48Exhibit 4-1. Commonly Used Lif e Cycle I m pact C a tegories
Impac t
Ca te gor y Scale E xam pl es of L C I Da ta (i.e. cl assific a t i on) Co mmon Po ssible

Ch arac teri z a t i on Factor Descripti o n of

Ch arac teri z a t i on Factor

Glo b al

Warm ing Gl o b al C a rb on Di oxi d e (C O 2 ) Nitrog en Diox id e (NO 2 ) Methane (CH 4 )

Ch lo rof l uo ro car bon s ( C FCs) Hy dr oc hl o r o f l u o r ocar bo ns (HCFCs)

Meth yl Br o m i d e ( C H 3 Br) G l ob al W a r m i n g Po ten tial Co nv erts LCI d a ta to

car bon d i ox id e ( C O 2 ) equi val e nt s No te: g l ob al warm in g pot e n t i a l s can be 50

, 1 0 0

, or 50 0 year

p o t en tials.

Stratos phe ric

Ozo n e Depl et i o n G l ob a l C h lo rof l uo ro car bon s ( C FCs) Hy dr oc hl o r o f l u o r ocar bo ns (HCFCs)

Halo ns Meth yl Br o m i d e ( C H 3 Br) Ozo n e De pleting

Po ten tial Co nv erts LCI d a ta to

t r i c hl or o f l u or o m et hane (C FC

- 1 1 ) e q ui val e nt s.

Acid ification Reg i on al

Local Su lfu r Ox id es (SOx) Nitrog en Ox i d es (NOx ) Hy dr oc hl o r i c Aci d ( H C L ) Hyd r oflou r ic Acid (HF)

Am m oni a (N H 4 ) Acid ification

Po ten tial Co nv erts LCI d a ta to
h ydr og en (H +) io n equi val e nt s.

E u t r o p h i c a t i o n L o c a l Phosphate (PO 4 ) Nitrog en Ox i d e (NO) Nitrog en Diox id e (NO 2 )

Nitrates

Am m oni a (N H 4 ) Eut r op hi cat i o n Po ten tial Co nv erts LCI d a ta to ph os ph at e (P O 4 ) equi val e nt s.

Ph ot oc hem i cal

Sm og L o c a l N o n

- m e thane hydroca r b o n (NM H C) Ph ot oc hem i cal

Ox i d en t C r eatio n Po ten tial Co nv erts LCI d a ta to

et hane (C 2 H 6 ) equi val e nt s.
Terrest rial

Tox i city Local Toxic chem ica l s with a re port ed

leth al con cen tratio n to rod e n t s LC 50 C o nv e r t s LC 50 d a ta to

eq u i v a len t s; u s es m u ltim e di a m odel i n g,

ex po su r e p a t h w a ys. Aqu a tic

Tox i city Local Toxic chem ica l s with a re port ed

leth al con cen tratio n to fish LC 50 C o nv e r t s LC 50 d a ta to

eq u i v a len t s; u s es m u ltim e di a m odel i n g,

ex po su r e p a t h w a ys.
Hum a n Health Glo b al Reg i on al

Local To tal releases to air, water, and

so il. LC 50 C o nv e r t s LC 50 d a ta to

eq u i v a len t s; u s es m u ltim e di a m odel i n g,

ex po su r e p a t h w a ys.
Resource Depl et i o n Glo b al Reg i on al

Local Qu an tity o f m i n e rals u s ed Qu an tity o f fo ssil fu els u s ed R e sou r ce De pl et i on Po ten tial Co nv erts LCI d a ta to a ratio o f qu an tit y o f

reso u r ce used vers us

q u a n tity o f reso urce left

in reserv e.
Lan d Use Glo b al Reg i on al

Local Qu an tity d i sposed o f in a landfill

or

ot her l a nd m odi fi cat i ons Land Av ailab i l ity Co nv erts m a ss o f so lid

wast e i n t o vol u m e usi n g an estim ated density.

Water Use Regio n al

Local Water use d or con s um ed Water Sh orta g e Po ten tial Co nv erts LCI d a ta to a ratio o f qu an tit y o f

wat e r use d ver s us

q u a n tity o f reso urce left

in reserv e.



### 49Step 3: Characterization

I m pact char acterization uses sci ence-based conversion f actors, call e d characteri z ation factors, to convert

and com b ine the LCI results into representative indicat ors of im pact s to hum an and ecological health.

Characteri zat ion factors also are co mmonly referred to as equivalency factors. Characteri zat ion provides

a way to directly com p are the LCI results within each i m pact cat egory

. In other words, charac terization

factors translate different inventor y inp u t s into dir ectly com p ar able im pa ct indicators. For exa m ple,

characte r izati on would provide an esti m ate of the rela tive terrestrial toxicity between lead, chromiu m , and

zinc.

Impact Cate gories and Associated En dpoints

The followin g is a list of several im pact categor ies an d endpo ints t h at identif y t h e im pacts.

Global Impacts

Global W a rming

- polar m e lt, soil m o isture l o ss, longer seas ons, forest loss/change, and change in

wind and oce a n patterns. Ozone Depletion

- increased ultr aviolet radiation.

Resource D e pletion -decreased resource s for future generations.

Regional Im pacts Photochemical Smog

- “sm og,” decreased visibility

, e y e i rritation, respiratory tract and lung irritation, and vegetation d a m a ge. Acidification - buildi ng cor r osion, water bod y acidification, vegetation effects, a nd soil effects.

Local Impac t s Human Health - increased m o rbidity and m o rtality

. Terre strial Toxicity

- decreased production and biodiversit y and decreased wildlife for hunting or viewing. Aquatic Toxic ity
- decreased aq uatic plant and insect production and biodiversit y and decreased

co mmercial o r recreational fishing. Eutrophicati o n – nutrients (phosphor ou s and nitrogen) ente r water bodies, such as lakes, estuaries

and slow- m oving streams, causing exces sive plant gro w th and ox yg en depletion.

Land Use - loss of terrestr i al habitat for wildlife and decreased landfill space.

Water U s e - l o ss of available water fro m groundwater and surface w a ter sources.

I m pact indica tors are ty pic a lly characterized using the following equation:

Inventor y Dat a × Characterization Factor = Im pact Indicators

For exam ple, all greenhouse gases can be expressed i n terms of CO 2 equivalent s by m u ltiply i ng the relevant LCI results by a C O 2 characteri zation factor and then co mbining the resulting im pact indicators
to pro v ide an overall indicator of gl obal warm ing potential.

Characteri zat ion can put these different quantities of chem icals on an equal scal e to deter m ine the am ount
of im pact each one has on global warm ing. T h e calcu lations show that ten po un ds of m e than e have a larger im pact on gl obal warming than tw enty po unds of chloroform

.



### 50Characterization of Glo b al Warm ing Im pacts

The following calculations dem onstrat e how charact e r ization factors can be use d to estim at e the global warm i ng potential (GWP) of de fined quantities of greenhouse gases:

Chloroform GWP Factor Value* = 9 Quantity = 20 pounds

Methane GW P Factor Value* = 21 Quantity = 10 pounds

Chloroform GWP Im pact = 20 po unds x 9 = 1 80

Methane GWP Im pact = 10 pou nds x 21 = 21 0

*Intergovern mental Panel on Clim ate Change (IPCC) Model

The key to im pact charact er ization is using the appr opriate chara c ter i zation factor. For som e i m pact categories, su ch as global war m ing and ozone depletion, there is a consensus on acceptable

characterizati on factors. F o r other im pact categories, such as resou r ce depletion, a consensus is still being developed. Exhibit 4-1 describes possible charact eriz a tion factors for some of the co mm only used life

cy cle im pact categories.

A properly referenced LCI A will document the source of each characterization factor to ensure that the y are relevant t o the goal and scope of the study

. For e x a m ple, m a n y characteriz a tion factors are based on

studies condu cted in Europ e . Therefore, the relevanc y of the E u ro pean characterization factors m u st be investigated before they can be applied to Americ an data.

TRAC I

EPA’ s Tool for the Reduction and Assess m e nt of Che m ical and other environm e n tal Im pa cts (TRACI) is an im pact assessment tool t h at w ill support consistency in envir o nmental decisi on making. TRACI allows the exam ination of t h e pote n tial for im pa cts as sociated with the raw materi al usage and chem ical releases resulting from the proce sses involved in producing a product. It allows

the user to exa m ine the potential fo r im p acts for a single life cy cle stage, or the whole life cy cle, and

to com p ar e the results between products or pr ocesses. The purpose of TRACI is to allow a

determ ination or a prelim in ary com p arison of two or m o re options on the basis o f the followin g environm ental im pact categories: ozone depleti on, gl obal warm ing, acidification, eutrophicati on, photochem i cal sm og, human health cancer, human health noncancer, hum an health criteria,

ecotoxicit y , f o ssil fuel use, land use, and water use (EPA 2003).

Step 4: Normalization

Nor m aliz ation is an LCIA tool used to express i m p act indicator data in a way tha t can be com p ared

am ong im pact categories. This procedur e normalizes the indicator results by dividing by a selected

reference value.

There are numerous m e th ods of selecting a referenc e value, including:

• The total em i ssions or resource use for a given area that m a y be global, regional or local



### 51• The total em i ssions or resource use for a given area on a per capita basis

• The ratio of one alternative to another (i.e., the baseline)

• The highest v a lue am ong all optio ns.

The goal and scope of the LCA m a y influence the choice of an appropriate reference value. Note that

norm a li zed data can only be co m p ared within an im pact cat egory. For exam ple, the effects of

acidification cannot be dir ectly com p ar ed with tho se of aquatic toxicity because the characteri zation

factors were calculated using di fferent s c ientific m e th ods.

Step 5: Grou ping Grouping assigns im pact categories into one or m o re sets to better facilitate the i n terpretation of the results into specific ar eas o f concern. Typically, gr ouping i nvol ves sorting or ranking indicat ors. The following are two possible way s to gr ou p LCIA data (ISO 1998):

• Sort indicators by characte r istics such a s e m issions ( e .g., air and water e m i ssi ons) or location (e.g., local, regional, or gl obal).

• Sort indicators by a ranking s y ste m , s u ch as high, low, or medium priority

. Ranking is based on

value choices

.

Step 6: Weig hting The weightin g step (also referred to as valuation) of an LCIA assigns weights or relative values to the

different im p act categorie s based on their perceived im portance or relevance. Weighting is im portant
because the im p act categories should also reflect study goals and stakeholder values. As stated earlie r
, harm ful air emissions could be of re latively h i gher concern in an air non-attainment zone th an the same

e m is sion level in an area with better air quality

. Be cause w e ighting is not a scientific process, it is vital that the weighting m e thodolog y is cl early explained and docum en ted.

Although weighting is wi dely used i n LCAs, the wei ghting stage is the least developed of the im pact

asse ss ment st eps and also is the one most likely to be challenge d for integrity. In genera l, weighting includes the following activities:

• Identif y i ng th e underl y i n g values of stakeholders

• Deter m ining weights to place on i m pact s

• Appl y i ng weights to im pact indicators.

Weighted dat a could possi bl y be com b ined across imp act categorie s, but the weighting procedure m u st be explicitl y doc umented. Th e un-weighted data should be shown tog e ther with the weighted results to

ensure a clear understanding of the assigned weights.

Note that in some ca ses, th e presentation of the im p act asse ss ment results alone often provides sufficient

inform ation for decision-making, particu l arly when t h e results are straightforward or o bvio u s. For

exa m ple, whe n the best-perform ing alter n ative is signi ficantly and meaningfully better than the others in

at least one im p act c a tegory

, and equal to the alte rnatives in the remaining im pa ct categories, then one alternative is clearly better . Therefore, any relative weighting of the im pa ct as sess ment re sults would not change its rank as first preference. The deci sion can be made with out the weigh ting step.

Several issues exist that make weighting a challenge. The first issue is subjectivity

. According to ISO 14042, any judgm ent of preferability is a subjective judgm ent regarding t h e relative im portan ce of one

i m pact cat egory over anot her. Additiona lly, these valu e judgm ents may change with location or tim e of

y ear. For exam pl e, so m e o n e located in Los Ange les, CA, m a y place m o re i m por tance on the values for



### 52photochem i cal sm og than would a person located in Chey enne, Wyom ing. The second issue is derived

from the first: how shoul d users fairly and cons istentl y m a ke decisi ons based on environm ental preferability

, given the subjective nature of weightin g? Developing a trul y obje c tive (or universally agreeable) set of weights or weighting m e thods is not feasible. Ho wever, sever al approaches to weighting

do exist and a r e used succe ssfully for de cision- m a ki ng, such as the Analy tic Hierarchy Process, the Modified Delphi Technique, and Decisi on Anal y s is Using Multi- Attribute Theor y

.

Step 7: Evaluate and Document the LCI A Results

Now that the i m pact potential for each se lected cat egor y has been calculated, the accuracy of the results

m u st be verified. The accuracy m u st be suffici ent to support t h e pur poses for perform ing the LCA as

defined in the goal and scope. When docu m enting the results of the life cy cle im p act as se ss ment,
thorou ghl y de scribe the m e thodol og y us ed in the anal y s is, define t h e sy stems analy zed and the boun daries that were set, and all assu mptions m a de i n perform ing the inventory analy s is.

The LCIA, like all other assessment tools, has inherent lim itations. Although the LCIA process follows a

sy stematic procedure, there are many underly i ng assum p tions and si m p lifications, as well su bjective

value choices

.

Depending on the LCIA methodology se lected, and/or the inventor y data on which it is based, so m e of

the ke y lim itations m a y include:

• Lack of spatial resolution – e.g., a 4,000-gallon a mmonia release i s worse in a s m all stre a m t h an in a large river.

• Lack of te m poral resolution – e.g., a five-ton re lease of particulate matter during a one m onth period

is worse than the sam e r e lease spread through the whole y ear.

• Inventor y spe c iation – e.g., broad in vent or y lis ting such as “V OC” or “ m etals ” do not provide enough infor m ation to accurately assess environm ental i m pacts.

• Threshold and non-threshold im pact – e. g., ten tons of contam inatio n is not neces sarily ten tim es worse than one ton of cont am ination.

The selection of m o re co mplex or site-specific i m pa ct m odels can help reduce the lim it ations of the

i m pact as ses s m ent’ s accura cy . It is im portant to document these li mitations and to include a

co m p rehensi v e description of the LCI A m e thodology , as well as a discussion of the underly i ng

assu m p tions, value choices , and known uncertainties in th e im pact m odel s with the num eri cal results of

the LCIA to be used in inte rp reting the r esults of the LCA.



### 53Chapter 5 Life Cycle In terpre tation

What is Life Cycle Inte rp retation? Life cy cle interpretation is a sy stematic t echnique to identify

, quantify, check, and evaluate information

from the re sults of the LCI and the LCIA, and communicat e the m effectively

. Life cy cle interpretation is the last phase of the LCA process.

ISO has defined the followi ng two o b j ectives of life cycle interpretat i on:

1. Analy ze results, reach conclusions, explain lim itatio ns, and provide reco mmendations based on the findings of the preceding phases of the LCA, and to report the results of the life cy cle interpretation in a transparent manner.

2. Provide a readily unde rstandable, com p lete, and consistent presentation of the results of an LC A study

, in accordance with the goal and s c ope of the study

. (ISO 1998b)

Comparing Alternatives Using Life C y cle Interp re tation Interpreting the results of an LCA is not as si m p le as t w o is better then three, therefore Altern ative A is the best choice! While conducting t h e LCI and LCIA it is necessar y to m a ke assum p tions, engineering

esti m ates, an d decisions based on y our values and th e values of involved stakeholders. Each of these

decisions m u st be included and comm un icated within the final results to clearly a nd com p rehe nsively explain concl u sions drawn from the data. In som e c a s es, it m a y not be possible to state that one

alternative is better than the others beca use of the unc er tainty i n the final results. This does not im ply that

efforts have been wast ed. The LCA process will still provide decision-m a ker s w ith a better understanding

of the environmental and health im pa ct s associ ated with each alte rnative, wh ere they occur (locally

, regionally

, or globally ) , an d the relative magnitude of each ty pe of im p act in co mparison to each of the proposed alternatives included in the study . This infor m ation m o re fully reveals the pros and c ons of each

alternative.

Can I Select an Alternative Based On ly on the Results of the LCA? The purpose of conducti ng an LCA is to better inform decision-makers by pro v i d ing a particu l ar type of

inform ation (often unconsidered), with a life cy cl e perspective of environm ental and h u m a n health

i m pacts associated with each product or process. However, LCA does not take into account t echnical performance, cost, or political and social acceptance. Therefore, it is reco mmend ed that LCA be used in conjunction with these other para m e t e r s

.

Key Steps to Interpr e ting the Results of the LCA The guidance provi ded in t h is chapter is a su mma ry of the inform ati on provided on life cy cle interpretation from the ISO standard entitled “ Environmental Management - Life Cycle As se ss ment - Life Cycle Inte rpr e tation ,” ISO 1404 3 (ISO 1 998b). Withi n the ISO standard, the fol l owing steps t o conducting a life cy cle interpretation are identified and discussed:

1. Identification of the Significant Issues B ased on the LCI and LCIA.

2. Evaluation w h ich Consider s Co m p leteness, Sensitivity, and Consist e ncy Checks.

3. Conclusions, Reco mmendations, and rep o rting.



### 54Exhibit 5-1 illustrates the s t eps of the life cy cle inte rpretation process in relation to the other phases of the LCA process. Each step is su mmarized below.

Step 1: Identify Significant Issues The first step of the life c y cle interpretation phase involves reviewin g inform ation from the first three phases of the LCA process in order to identify the data el e m ents that contribute m o st to the results of both

the LCI and LCIA for each product, pr ocess, or serv i ce, otherwise known as “significant issues.”

The results of this effort are used to evaluate th e co mpleteness, sen sitivity

, and c onsistency of the LCA study (Step 2). The identification of significan t issues guides the evaluation step. Because of the

extensive amount of data collected, it is onl y feasibl e within reasonable ti m e and resources to assess the

data elements that contribu te signifi cantly to the outcome of the results.

Before deter m ining which parts of the LCI and LCIA have the greatest influence on the results for each alternative, the previous phases of the L C A should be reviewed in a co m p rehensive manner (e.g., study goals, grou nd rules, im pact category wei ght s, results, external invol vem e nt, etc.).

Review the information collected and the presentations of results developed to deter m ine if the goal and scope of the LCA study h a ve been m e t. If the y have, the significance of the results can then be

determ ined.



### 55Deter m ining significant issues of a product sy stem may be sim p le or com p lex. For assistanc e in

identif y i ng environm ental i ssues and determ ining their significance , the following approaches are

reco mmended:

• Contributio n Analysis - the contribution of the life cycle stages or groups of pr ocesses are co m p ared

to the total re sult and examined for relevance.

• Dominance Analysis - stati s tical tools or other techniques, such as quantitative or qualitative ranking (e.g., ABC A n aly s is), are used to identify significan t contributi ons to be exam in ed for relevance.

• Anomaly Ass essm ent - based on previou s experience, unusual or su rprising deviations from expected

or norm a l res u lts are observed and examined for relevance.

Significant issues can incl ude:

• Inventory para m e t e rs like e n ergy use, emissions, waste

, etc.

• I m pact c a teg o ry indicators like res ource use, e m issio n s, waste, etc.

• Essential contributions for life cy cle sta g es to LCI or LCIA results such a s individual unit processe s or groups of processes (e. g ., transportat i on, energy pr oduction)

.

Step 2: Evaluate the Co m p leteness, Se nsitivity

, and C onsistency of the Data The evaluation step of the interpretation phase establis hes the confidence in and reliability of the results

of the LCA. This is acco mplished by com p l e ting the following tas k s to ensure that products/processe s are fairly com p ar ed:

1. Co m p leteness Check - examini ng the co m p leteness of the stud y

.

2. Sensitivity Check - assessi ng the sens itivity of the significant data elem ents that influence the results

m o st greatly

.

3. Consistency Check - evaluating the co nsistency use d to set s y stem boundaries, collect data, make

assu m p tions, and allocate data to im pa ct categories for each alternat ive.

Each technique is su mmar i zed below.

Completeness Check - The co m p letenes s check ensure s that all relevant inform ation and data needed for the interpretation are available and com p lete. A ch eck list should be developed to indicate each significant

area repre sent e d in the results. Data can be orga nized by life c y cle stage, different processes or unit operations, or ty pe of data represented (r aw materials, energy , transportation, environm ental re lease to air, land, or water). Using the established c h ecklist, it is possible to ve rify that the data co m p risin g each area

of the results are consistent with the s y stem boundari es (e.g., all life cy cle stages are included) and that the data is representative of the specified area (e.g., accounting for 90 percent of all raw m a t e rials and

environm ental releases). The result of this effort will be a checklist indicating that the results for each product/pr o cess are co m p lete and reflecti v e of the stated goals and s c ope of the L C A study . If

deficiencies are noted, then a fair co m p arison cannot b e perform ed and additi onal efforts are required to fill the gaps. In some cases, data may not be ava ilable to fill the data gaps; under t h ese circu m st ances, it

is neces sary to report the difference s in the data w ith the final results and esti m at e the i m pact t o the

co m p arison either quantitat i vely (percent uncertain t y ) or qualitativel y (Alternative A’s reported result

may be higher because “ X ” is not included in its assess ment).

Sensitivity Check - The objective of the sensitivit y check is to evaluate the reliabi lit y of t h e results by

deter m ining whether the uncertainty in the significan t issues identified in Step 1 affect the dec i sion

### 56maker’s ability to confi d ent l y draw com p arative c oncl u sions. A sensitivit y check can be performed on the significant issues using the following three common techniq u es for data quali ty anal y s is:

1. Contributi on Analy s is – Id entifies the data that has the greatest con t ribution on the im pa ct indicator

results.

2. Uncertainty Analy s is – D escribes the v a riability of the LCIA data to determ ine the significance of

the im pa ct indicator results.

3. Sensitivit y Analy s is – Mea s ures the extent that changes in the LCI results and characterization

m odel s affe ct the im pa ct indicator results.

Additional guidance on how to conduct a contribution, un certaint y , or sensitivit y analy s is can be found in

the EPA document entitled “Guidelines f o r Assessing the Quality of Life Cy cle Inventory Analy s is,” April 1995, E P A 530-R-95-010. As part of the LC I and LCIA pha ses, a sensitivity, uncertaint y , and/or

contributi on a n aly s is m a y have been conducted. Th ese results can be used as the sensitivity check. As part of the goal, scope, and definition phase of the LC A process, the data quality and accuracy goals were defined. Verify that these goals have been met with the sensitivity check. If de ficiencies exist, then the

accuracy of the results m a y not be sufficient to suppor t the decisions to be m a de and additional efforts are required to i m prove the accuracy of th e LCI data co ll ected and/or im pa ct m ode ls used in the LCIA. In

so m e c ase s, better data or im p act m odels may not be available. Under these circ umstance s, re port the

deficiencies f o r each relev a nt significant issue a nd esti m ate the i m p act to the com p arison either quantitativel y or qualitative l y.

Consistency Check - The consistency check deter m in es whethe r the assu m p tions, m e thods, and data used throughout the LCA process are consistent with the goal and scope of the study, and for each product/pr o cess evaluated. Verify ing and docum enting that the study was co m p leted as intended at the

conclusion increas es confi d ence in the final results.

A form al checklist should be devel oped to comm unicate the results of the consist e ncy check. Exhibit 5-2 provides exam ples of the types of infor m ation to be i n cluded in t h e checklist. The goal and scope of the

LCA determ ines which categories shoul d be used.

Depending upon t h e goal and scope of t h e LCA, so me inconsistency m a y be acceptable. If any inconsistency is detected, document the role it pla y ed i n the overall consistency evaluation.

After co m p let i ng steps 1 and 2, it has been determ ined that the results of the im pa ct ass ess ment and the

underl y i ng inventor y data are co m p let e , com p arab le, and acceptabl e to draw conclusions and make

reco mmendat i ons. If this i s not true, stop! Repeat st eps 1 and 2 until the results will be able to support the original goals for perfor m ing the LCA.



### 57Exhibit 5-2. Examples of Checklist Categories and Potential Inconsistencies Category Example of Inconsistency

Data Source Alternative A is based on literature and Alternative B is based on mea s ured data.

Data A ccurac y For Alternative A, a detail ed pro cess fl ow diagra m is used to develop the LCI data. For Alternative B, li m ite d process in formation w as avail a ble and the LCI data developed was for a process that was not described or analy zed in detail.

Data Age Alternative A uses 1980' s era raw mat e ri als manufact uring data. Alternative B used a

one y ear-old stud y

. Technological Representatio n Alternative A is bench-scale l a boratory m odel. Alternative B is a full-scal e productio n pl ant operation.

Tem poral Representatio n Data for Alt e rnative A d escribe a recently developed technology . Alternate B describes a technology m i x, includi ng re cently built a nd ol d plants. Geographical Representatio n Data for Alternative A were data from technolo g y em ploy ed under Eur o pean environm ental standards. Alternative B uses the data fro m technology em ploy ed

under U.S. en vironm ental standards. Sy stem Boundaries,

Assu m p tions,

& Models Alternative A uses a Global War m ing Poten tial m o del based on 500 y ear pot ential.

Alternative B uses a Globa l War m ing Poten tial m ode l based on 100 y ear potential.

Step 3: Draw Conclusions and Reco mmendations The objective of this step is to interpret t h e results of the life cy cle im p act as se ss ment (not the LCI) to

deter m ine wh ich product/process has the overall least i m pact to human health a nd the environment,

and/or to one or m o re specific areas of concer n as defined b y t h e g o al and scope of the stud y.

Depending upon t h e scope of the LCA, t h e results of th e im pact assessment will return either a list of unnorm a li zed and un-weight ed im pact indicators for each im pact cat egor y for t h e alternatives, or it will return a singl e grouped, nor m alized, and weighted sco re for each alt e rnative, or something in between,

e.g., norm a lized but n o t weighted.

In the case where a score i s calculated, t h e reco mme n d ation m a y be to accept the product/process with the

lowest score. Or, it could be to investigate the r easons how the proc ess could be m odified to lower the

score. Howev e r, do not for g et the underl y i ng assum p t i ons that went into t h e analy s is.

If an LCIA st ops at the characteriz ation stage, the LC IA interpretat i on is less cle a r-cut. The conclusions

and reco mmendations rest on balancing the potential hum an health and environmental i m pacts in the light

of stud y goal s and stakeholder concerns.

A few words of caution sh ould be noted . It is im portant to draw conclusions an d prov ide

reco mmendat i ons based only on the facts. Unde rstanding and comm unic a ting the uncertainties and

lim it ations in the results is equally as i m portant as the final reco mmendations. In some insta n ces, it m a y not be clear which produc t or process is better because of the under l y i ng uncertainties and lim i t ations in

the methods used to conduct the LCA or the availability of good dat a , time, or resources. In thi s situation,

the results of the LCA are still valu able. They can be used to help i n form deci sion-makers abo u t the

hum an health and environmental pr os a nd cons, unde rstanding the significant impacts of each, where they are occurring (locally , regionally

, or globally ), and the relative ma gnitude of each ty pe of im pact in

co m p arison to each of the proposed a lternatives included in the study

.



### 58Reporting the Result s Now that the LCA has bee n com p leted, the material s m u st be ass e m bl ed into a co m p rehensi v e report
docum enting the study i n a clear and organized m a nner. This will help communicate the result s of the

asse ss ment fa irly, com p lete ly, and accurately to others interested in the results. The report presents the results, data, methods, assum ptions, a nd lim itations in sufficient d e tail to allow the reader to co m p rehend

the com p lexit i es and trade-offs inherent in the LCA study

.

If the results will be reported to som e on e who was not invol ved in the LCA study, i.e., third-party stakeholders, this report will serve as a reference document and should be pr ovided to them to help
prevent any misrepre senta tion of the results.

The reference docum ent sh ould co nsist o f the followin g elem ents (ISO 1997):

1. Ad m i nistrative Information

a. Name and address of LCA practitione r (who conducte d the LCA study )

b. Date of report

c. Other contact inform ation or release inf o rmation

2. Definition of Goal and Scope

3. Life Cy cle Inventory Analy s is (data coll ection and calculation proc edures)

4. Life Cy cle Im p act Assessm ent ( m eth odology and results of t h e i m pact assessment that was performed)

5. Life Cy cle Interpretation

a. Results

b. Assu m p tions and lim itations

c. Data quality assessment

6. Critical Revie w (internal and external)

a. Name and affiliation of reviewers

b. Critical review reports

c. Responses to reco mmendat i ons

Critical Revi ew The desirability of a peer review process has been a major focus of di scussion in many life-c y cle analy s is

forum s . The discussion stems fro m concerns in f our a r eas; lack of understanding regarding t h e methodolog y used or the scope of the stu d y , desire to verify data and the anal y s t’s co m p ilations of data, questioning key assum p tions and the overall results, a nd comm unic a tion of results. For these reasons, it

is reco mmen d ed that a peer review process be est ablis hed and im p l em ented early in any study that will be used in a public forum

.

The followin g discussion i s not inten d ed to be a bl uepr int of a spe c ific approach. Instead, it is m eant to point out issues that the practitioner or sponsor shou ld keep in m i nd when establishing a peer review procedure. Overall, a peer review process s hould addr ess the four areas previously identified:

• Scope/boun d a ries methodolog y

• Data acquisition/com p ilation

• Validity of ke y assu m p tions and results

• Co mm unication of results.



### 59The peer review panel should participat e in all ph ases of the study: (1) reviewing the pur pose, sy stem boundaries, assu m p tions, and data collection appr o ach; (2) reviewing the com p iled data and the

associat ed quality m easures; and, (3) reviewing the draft inventory report, including the intended

co mm unicati on strategy

.

A spreadshee t, such as the one presented in Appendix A would be useful in addressing many of the issues

surroundi ng s c ope/boundaries m e thodology

, data/com pilation of data, a nd vali dit y of assumptions and

results. Crite ria m a y need to be established for co mm unic a tion of results. These criteria coul d include showing how changes in key assum p tions could affect the study r esults, and guidance on how to publish

and comm unicate results without disclosing pr oprietary data.

It is generally believed that the peer review panel should consist of a diverse group of t h ree to five

indivi duals representing various sectors, such as feder a l, state, and local governments, academi a , industr y , environm ental or consum er groups, and LCA practitioners. Not all sectors need be represented on ever y panel. The credentials or background of indivi duals should include a reputation f o r objectivit y, experience wi th the technical framework or conduct of life-cy cle analy s is studies, and a willingness to work as part of a team . Issues for which guidelin es are still under development include panel selection,

num ber of reviews, using t h e same reviewers for a ll li fe-cy c le studies or vary ing the me m b er s between studies, and having the revi ew open to the public prior to its release. The issue of how the revi ews should be performed raises a nu mber of questions, such as these: Should a standard spreadsheet be required?

Should oral as well as written comments from the review ers be accepted? How m u ch tim e sh ould be

allotted for review? Who pay s for the review process ?

The peer review process should be flexible to acco mmoda te variations in the appl ication or scope of lifecy cle studies. Peer review should im prove the conduc t of these studies, increase t h e understanding of t h e results, and aid in further identif y i ng and subsequently reducing an y environm enta l consequences of products or m a terials. EPA supports the use of p eer reviews as a mechanism to increase the quality and consistency of life-cy cle inventories.

Conclusion Adding life c y cle assessment to t h e decision-m a king process provides an understanding of the hum an health and environm ental i m p acts that tr aditionally is not considered when select ing a product or process. This valuable inform ation provides a way to account f o r the full im pacts of decisions, especially those

that occur outside of the site that are dire ctly influenced by the selec tion of a product or process.

Remem b er, LCA is a tool to better infor m decision- makers and should be inclu d e d with other decision criteria, such as cost and performance, to make a w e ll- balanced deci sion.



### 60

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. 1986. EPA Quality Assurance Managem e nt Staff. Development of Data Quality Objectives: Description of Stages I and II.

Hendrickson, C.T., Lave L., and Matthe w s, H.S. 200 6. Environmental Life Cycle Assessment of Goods

and Services: An Input-Out put Approach. Resources f o r the Future, Washington, DC, ISBN 1- 933115-

23-8.

International Standards Organization. 1 997. Environmental Management - Life Cycle As se ss ment - Principles and Framework ISO 140 40.

International Standards Organization. 1 998. Li fe Cycle Assessment - Impact Assessment ISO 14042.

International Standards Organization. 1 998b

. Environmental Management - Life Cycl e Asse s s ment - Life Cycle Interpretation ISO 1 4043

.

Jensen, A.A. and Remmen, A. 200 4. “Background Re port for a UNEP Guide to Life Cy cle Managem e nt - A Bridge to Sustainable Products.” Final draft 30 Decem b er 2004. UNEP/SETAC Life Cy cle Initiative.

Available from: http:// www.u n eptie.org/pc/ sustain/reports/lcini/Bac kground%20docu m e nt%20G uide%20LIFE%20CYCL

E% 20MANAGEMENT% 2 0rev% 20final% 20draft.pdf . Accessed 08 June 2005.



### 61Meadows, D. H. et al. 1972. The Limits to Growth: A Report for th e Club of Ro me’s Project on the Predicament of M ankind. Universe Books, New York. P. 20 5.

Society of En vironm ental Toxicolog y a nd Chem istry

. 199 1. A Tec hnical Framework for Life Cycle

Asses sment

. Fava, J., Denison, R., Jones

, B., Curran, M.A., Vigon, B., Selk e, S., and Barnum , J. (eds).

Society of En vironm ental Toxicolog y a nd Chem istry

. 19 93. Guidelines for Life Cycle As ses s m ent: A ‘Code of Pra c tice.’ Consoli, F., Allen, D., Boustead, I., Fa va, J., F r anklin, W., Jensen, A.A., Oude, N., Parrish, R., Perrim a n, R., Postlethwaite, D., Quay , B., Seguin, J., an d Vigon, B. ( e ds).

Society of En vironm ental Toxicolog y a nd Chem istry

. 199 7. Life Cycle Impact A sses sm ent: The State-ofthe-Art . Barnthouse, L., Fa va, J., Hum p hrey s, K., Hunt , R., Laibson, L., Noessen, S., Owens, J.W., Todd, J.A., Vigon, B., Wietz, K., and Youn g, J

. (eds).

Society of En vironm ental Toxicolog y a nd Chem istry

. 200 4. Life-C ycle M anagement . Hunkeler, D., Rebitzer, G., Finkbeiner, M., Schm idt W-P., Jensen , A.A., Stranddorf, H., and Christiansen, K.



### Werner, A.F. 1991. Product Lifecycle Assessment: A Strategic Approach . Proceedings of the Global Pollution Prevention ’91 Conference, W a shington, D.C.

62Appendix A Sample Inventory Spreadsheet

(This is a fictitious example of the life cycle inventory for a gasoline system and does not represent real data).



### 63PROCESS NAME:Fictitious Gasoline Life Cycle InventoryPROCESS ID:GasolineREFERENCEFLOW:1000Units:gallonsof:GasolinePROCESS DESCRIPTION:Summary of LCI to extract, produce, anddistribute 1,000 gallons of gasoline usedto fuel a typical passenger automobile in the US.BASIS OF CALCULATIONSSummerWinterAverageUnitsReferenceOxygen Content2.11.90.02percentEPA, OTAQ; MOBILE 6MolecularWeight88g/molwww.chemfinder.comOxygenate Content by Volume11.05percent by volumeOxygenate Content by Weight11.15percent by weightFuel Economy Estimated for Average Car ByFuel Type20.22miles/galMOBILE 6Petroleum Refining Process Efficiency(mass outputs/mass inputs)Petroleum Refinery Process Efficiency (mass basis)92percentEIAGREET v1.6 Published Petroleum Refinery Efficiency85percentGreet1.6Process Efficiency Used in Calculations85percentProcess InputsMaterialCoal9.88E+01lbCrudeOil5.64E+02galNaturalGas3.23E+02SCFUranium6.69E-02lbWood3.99E+00lbDrillingFluidsUnknownProcess OutputsProductGasoline594galCalculatedCo-ProductN/AAir Emissions64Mat. P&DFuel P&DFuel UseProcessTotalUnitsVolatile Organic Compounds (VOC)1.86E-011.49E-012.98E-011.36E+011.42E+01lbCarbon Monoxide (CO)4.69E-014.78E-012.32E+003.00E+023.03E+02lbNitrogen Oxides (NOx)1.51E+001.64E+008.33E+002.26E+013.41E+01lbPM106.16E-022.06E-012.45E-016.79E-011.19E+00lbSulfur Oxides (SOx)6.41E-012.17E+002.52E+001.44E+006.77E+00lbMethane5.60E-011.26E+003.18E-011.70E+003.84E+00lbNitrous Oxide (N2O)3.91E-034.38E-032.85E-023.68E-02lbCarbon Dioxide (CO2)2.20E+023.75E+021.56E+031.20E+041.41E+04lbVOC loss: evaporation1.39E+011.39E+01lbVOC loss: spillage2.70E-042.36E-032.62E-03lb1 1 1-Trichloroethane2.19E-052.19E-05lb1 2 3-Trichloropropane9.67E-069.67E-06lb1 2 4-Trichlorobenzene5.8E-075.8E-07lb1 2 4-Trimethylbenzene1.07E-041.02E-041.23E-011.23E-01lb1 2-Dibromoethane1.24E-061.19E-061.61E-051.86E-05lb1 2-Dichloroethane3.2E-063.06E-064.15E-054.78E-05lb1 3-Butadiene2.9E-052.77E-058.39E-028.40E-02lb2 2 4-TM-Pentane1.20E+001.20E+00lb2 2 5-TM-Hexane1.39E-011.39E-01lb2 3 3-TM-Pentane2.22E-012.22E-01lb2 3 4-TM-Pentane2.21E-012.21E-01lb23-Dimethylbutane1.39E-011.39E-01lb24-Dimethylphenol1.01E-071.01E-07lb2-Methyl-2-butene9.19E-029.19E-02lb2-Methylhexane1.57E-011.57E-01lb2-Methylpentane2.84E-012.84E-01lb3-Methylhexane1.64E-011.64E-01lb3-Methylpentane1.82E-011.82E-01lbAcenaphthene9.23E-059.23E-05lbAcenaphthylene5.20E-045.20E-04lbAcetonitrile4.29E-064.29E-06lbAcetophenone2.75E-062.75E-06lbAcreolin4.29E-073.2E-061.57E+038.21E-038.21E-03lbAluminum (fume or dust)2.36E-082.36E-08lb65Ammonia1.32E-032.43E-032.68E+002.68E+00lbAnthracene5.88E-075.62E-071.14E-041.16E-04lbAntimony2.17E-071.62E-061.85E-063.69E-06lbAntimony Compounds5.9E-075.64E-077.65E-068.80E-06lbArsenic9.85E-077.34E-067.60E-058.43E-05lbAsbestos(friable)0.00E+00lbBarium8.80E-088.80E-08lbBariumCompounds1.05E-061.05E-06lbBenzene1.60E-032.26E-036.38E-016.42E-01lbBenzo(a)anthracene1.30E-051.30E-05lbBenzo(a)pyrene1.30E-051.30E-05lbBenzo(b)fluoranthene1.54E-051.54E-05lbBenzo(g,h,i)perylene3.24E-053.24E-05lbBenzo(k)fluoranthene1.54E-051.54E-05lbBeryllium1.12E-078.35E-079.47E-07lbBiphenyl2.31E-051.05E-053.73E-044.06E-04lbButraldehyde5.58E-065.58E-06lbCadmium2.14E-071.6E-062.79E-081.84E-06lbCarbon Disulfide1.89E-061.81E-062.45E-052.83E-05lbCarbon Tetrachloride2.43E-067.29E-062.16E-053.13E-05lbCarbonyl Sulfide5.23E-055.01E-057.58E-051.78E-04lbCertain Glycol Ethers3.11E-053.11E-05lbChlorine4.06E-053.97E-055.25E-046.05E-04lbChlorineDioxide4.29E-094.29E-09lbChlorobenzene0.00E+00lbChlorodifluoromethane8.34E-067.99E-061.08E-041.25E-04lbChloromethane2.97E-062.97E-06lbChromium1.28E-069.52E-067.51E-081.09E-05lbChromium Compounds9.85E-089.42E-081.28E-061.47E-06lbChromiumIII7.85E-057.85E-05lbChromiumVI5.23E-055.23E-05lbChrysene1.30E-051.30E-05lbCobalt7.22E-074.86E-063.22E-085.62E-06lbCobalt Compounds2.48E-092.38E-091.02E-061.03E-06lbCopper3.01E-083.01E-08lb66Copper Compounds3.2E-073.07E-074.16E-064.78E-06lbCresol (mixed Isomers)3.87E-063.7E-065.02E-055.78E-05lbCumene1.42E-033.36E-035.10E-039.88E-03lbCumeneHydroperoxide1.09E-051.09E-05lbCyanideCompounds8.07E-058.07E-05lbCyclohexane2.54E-042.43E-043.30E-033.79E-03lbDibenz(a,h)anthracene0.00E+00lbDicyclopentadiene3.94E-063.94E-06lbDiethanolamine2.94E-052.82E-053.82E-044.40E-04lbDioxins2.36E-121.76E-111.99E-11lbEthylbenzene7.00E-041.11E-033.44E-013.46E-01lbEthylene3.62E-043.46E-044.69E-035.40E-03lbEthylene Glycol1.89E-051.81E-052.45E-042.82E-04lbEthyleneOxide4.29E-064.29E-06lbFormaldehyde2.93E-053.95E-052.32E-012.32E-01lbFluoranthene1.15E-041.15E-04lbFluorene1.91E-041.91E-04lbHydrazine1.63E-061.63E-06lbHydocarbons (non CH4)2.49E-021.86E-012.11E-01lbHydrochloric Acid2.27E-031.63E-021.26E-031.98E-02lbHydrogenCyanide4.21E-054.21E-05lbHydrogen Fluoride3.50E-042.28E-036.52E-043.28E-03lbIndeno(123cd)pyrene9.71E-069.71E-06lbIsopentane4.1E-074.55E-014.55E-01lbIsopropylAlcohol3.59E-063.59E-06lbKerosene1.09E-058.09E-059.18E-05lbLead1.73E-061.29E-051.29E-081.46E-05lbLead Compounds2.08E-071.99E-072.69E-063.10E-06lbm-Xylene9.61E-041.66E-034.01E-036.63E-03lbManganese2.97E-062.21E-054.43E-056.94E-05lbManganeseCompounds2.23E-062.23E-06lbMercury8.13E-076.06E-062.31E-053.00E-05lbMercuryCompounds1.29E-071.29E-07lbMetals4.5E-063.35E-053.80E-05lbMethanol1.05E-031.00E-031.36E-021.57E-02lb67Methyl Ethyl Ketone4.91E-044.70E-046.37E-037.33E-03lbMethyl Isobutyl Ketone3.37E-053.22E-054.37E-045.03E-04lbMethyl Tert-Butyl Ether3.42E-043.27E-042.30E+002.30E+00lbMethylene Chloride1.85E-061.38E-050.00E+001.56E-05lbMolybdenum Trioxide4.50E-074.31E-075.84E-066.72E-06lbn-Butane1.10E-011.10E-01lbn-ButylAlcohol2.45E-052.45E-05lbn-Pentane7.21E-045.29E-041.91E-011.92E-01lbn-Hexane7.21E-046.90E-044.13E-014.14E-01lbn-Heptane1.90E-011.90E-01lbn-Octane4.12E-034.12E-03lbn-nonane3.19E-033.19E-03lbn-Decane3.07E-033.07E-03lbn-Undecane1.75E-031.75E-03lbn-Dodecane2.31E-032.31E-03lbn-Tridecane2.74E-032.74E-03lbn-Tetradecane2.97E-032.97E-03lbn-Pentadecane2.83E-032.83E-03lbn-Hexadecane2.67E-032.67E-03lbn-Heptadecane2.62E-032.62E-03lbn-Octadecane1.60E-031.60E-03lbn-Nonadecane1.95E-031.95E-03lbn-Icosane1.79E-031.79E-03lbn-Henicosane1.66E-031.66E-03lbn-Docosane1.62E-031.62E-03lbn-Methyl-2-Pyrrolidone3.8E-053.64E-054.93E-045.67E-04lbn-Nitrodimethylamine9.06E-086.75E-077.66E-07lbNaphthalene7.36E-055.09E-051.76E-021.77E-02lbNickel6.68E-064.83E-059.81E-051.53E-04lbNickel Compounds5.81E-065.56E-067.53E-058.67E-05lbNitrateCompounds0.00E+00lbo-Xylene9.39E-041.64E-033.73E-036.31E-03lbOther Aldehydes8.17E-056.08E-046.90E-04lbOther Organics1.24E-049.27E-041.05E-03lbp-Xylene9.94E-041.69E-031.61E-034.30E-03lb68Particulates (total)3.61E-022.69E-010.00E+003.05E-01lbPerchloroethylene4.10E-073.05E-060.00E+003.46E-06lbPhenanthrene3.00E-051.31E-054.81E-045.24E-04lbPhenols2.52E-053.15E-053.12E-043.69E-04lbPolycyclic Aromatic Compounds7.74E-067.41E-061.00E-041.16E-04lbPropionaldehyde8.97E-038.97E-03lbPropylene6.65E-046.36E-048.63E-039.93E-03lbPyrene1.57E-041.57E-04lbQuinoline1.01E-051.01E-05lbRadionuclides (Ci)8.90E-066.63E-057.52E-05lbSelenium3.09E-062.30E-052.61E-05lbSeleniumCompounds1.07E-071.07E-07lbStyrene1.23E-061.18E-064.10E-024.10E-02lbSulfuric Acid1.36E-031.30E-031.76E-022.03E-02lbTert-Butyl Alcohol9.20E-078.81E-071.19E-051.37E-05lbTetrachloroethylene1.03E-059.81E-061.33E-041.53E-04lbToluene3.36E-034.36E-032.00E+002.00E+00lbToluene-2 6-Diisocyanate4.14E-064.14E-06lbTrichloroethylene1.08E-051.30E-051.35E-041.59E-04lbVanadium5.93E-065.93E-06lbVinylAcetate1.51E-051.51E-05lbXylene (mixed isomers)5.52E-045.28E-041.31E+001.31E+00lbZinc (fume or dust)1.09E-061.05E-061.42E-051.63E-05lbZinc Compounds8.05E-067.71E-061.04E-041.20E-04lbAcetaldehyde0.00E+000.00E+006.72E-026.72E-02lbTotal2.24E+023.85E+021.57E+031.24E+041.45E+04lbWater EmissionsMat. P&DFuel P&DFuel UseProcessTotalUnits111-Trichloroethane0.00E+00lb123-Trichloropropane0.00E+00lb124-Trichlorobenzene0.00E+00lb1 2 4-Trimethylbenzene3.99E-071.6E-062.17E-012.17E-01lb1 2-Dibromoethane9.6E-109.41E-101.29E-081.48E-08lb12-Dichloroethane2.15E-092.15E-09lb1 3-Butadiene1.27E-071.25E-071.70E-061.96E-06lb692 2 4-TM-Pentane7.97E-017.97E-01lb2 2 5-TM-Hexane2.49E-012.49E-01lb2 3 3-TM-Pentane3.96E-013.96E-01lb2 3 4-TM-Pentane3.95E-013.95E-01lb23-Dimethylbutane2.49E-012.49E-01lb24-Dimethylphenol2.25E-072.25E-07lb2-Methyl-2-Butene1.64E-011.64E-01lb2-Methylhexane2.80E-012.80E-01lb2-Methylpentane5.07E-015.07E-01lb3-Methylhexane2.93E-012.93E-01lb3-Methylpentane3.25E-013.25E-01lbAcetaldehyde5.25E-075.25E-07lbAcetonitrile0.00E+00lbAcetophenone0.00E+00lbAcid4.96E-103.7E-094.19E-09lbAluminum (fume or dust)0.00E+00lbAmmonia1.02E-042.25E-041.11E-031.44E-03lbAnthracene8.07E-078.07E-07lbAntimony9.17E-079.17E-07lbAntimony Compounds1.51E-071.48E-072.03E-062.33E-06lbArsenic8.37E-088.37E-08lbBarium3.99E-063.99E-06lbBariumCompounds1.37E-051.37E-05lbBenzene4.25E-041.16E-038.58E-028.73E-02lbBeryllium4.94E-084.94E-08lbBiphenyl0.00E+001.15E-067.19E-071.87E-06lbBiological Oxygen Demand (BOD)1.11E-038.31E-039.42E-03lbBoron5.46E-064.07E-054.62E-05lbCadmium3.60E-042.83E-041.63E-032.27E-03lbCarbonDisulfide8.59E-098.59E-09lbCertain Glycol Ethers3.33E-063.33E-06lbChlorine2.56E-062.51E-063.43E-053.94E-05lbChromates5.46E-064.07E-054.62E-05lbChromium5.65E-075.65E-07lbChromium Compounds9.24E-079.05E-071.24E-051.42E-05lb70Cobalt4.81E-064.81E-06lbCobaltCompounds3.18E-063.18E-06lbCopper1.07E-081.07E-08lbCopper Compounds3.42E-073.35E-074.59E-065.27E-06lbCresol (mixed isomers)3.43E-073.36E-074.60E-065.28E-06lbCumene7.80E-044.13E-031.92E-036.83E-03lbCyclohexane3.15E-073.09E-074.23E-064.85E-06lbDiethanolamine1.21E-019.00E-012.55E-051.02E+00lbEthylbenzene2.26E-047.83E-041.40E-011.41E-01lbEthylene1.42E-061.42E-06lbEthylene Glycol4.48E-053.24E-042.02E-053.89E-04lbFluorine5.71E-055.71E-05lbHydrogenFluoride1.52E-071.52E-07lbIron6.62E-014.03E-013.08E+004.14E+00lbIsopentane9.86E-019.86E-01lbLead1.42E-071.42E-07lbLead Compounds1.40E-071.37E-071.87E-062.15E-06lbm-Xylene1.41E-031.41E-03lbManganese2.64E-021.61E-021.23E-011.65E-01lbManganeseCompounds3.41E-063.41E-06lbMercury4.65E-059.99E-051.68E-043.14E-04lbMethanol3.15E-041.95E-041.55E-032.06E-03lbMethyl Ethyl Ketone1.32E-061.29E-061.77E-052.03E-05lbMethyl Isobutyl Ketone4.96E-094.86E-096.65E-087.64E-08lbMethyl Tert-Butyl Ether1.88E-052.57E-051.32E+001.32E+00lbMolybdenum Trioxide5.99E-075.87E-078.03E-069.22E-06lbn-Butane1.96E-011.96E-01lbn-ButylAlcohol2.58E-082.58E-08lbn-Pentane3.75E-013.75E-01lbn-Hexane3.38E-072.07E-063.14E-013.14E-01lbn-Heptane1.74E-011.74E-01lbn-Methyl-2-Pyrrolidone6.72E-056.72E-05lbn-Octane1.65E-021.65E-02lbn-Nonane1.28E-021.28E-02lbn-Decane1.23E-021.23E-02lb71n-undecane7.00E-037.00E-03lbn-Dodecane9.24E-039.24E-03lbn-Tridecane1.10E-021.10E-02lbn-Tetradecane1.19E-021.19E-02lbn-Pentadecane1.13E-021.13E-02lbn-Hexadecane1.07E-021.07E-02lbn-Heptadecane1.05E-021.05E-02lbn-Octadecane6.39E-036.39E-03lbn-Nonadecane7.80E-037.80E-03lbn-Icosane7.16E-037.16E-03lbn-Henicosane6.63E-036.63E-03lbn-Docosane6.46E-036.46E-03lbNaphthalene1.47E-044.13E-046.59E-041.22E-03lbNickel4.06E-074.06E-07lbNickel Compounds5.53E-063.18E-051.95E-055.69E-05lbNitrates2.73E-032.68E-033.67E-024.21E-02lbo-Xylene1.41E-031.41E-03lbOil5.58E-044.16E-030.00E+004.72E-03lbp-Cresol7.83E-077.83E-07lbp-Xylene1.41E-031.41E-03lbPhenanthrene9.23E-089.23E-08lbPhenol1.35E-041.00E-032.07E-051.16E-03lbPolycyclic Aromatic Compounds4.98E-084.88E-086.68E-077.66E-07lbPropylene1.43E-061.43E-06lbSelenium6.12E-076.12E-07lbSeleniumCompounds4.94E-064.94E-06lbSodiumNitrite6.01E-056.01E-05lbStyrene1.01E-071.01E-07lbSulfates2.68E-042.00E-030.00E+002.27E-03lbSulfuric Acid2.04E-021.52E-010.00E+001.73E-01lbTert-ButylAlcohol1.76E-051.76E-05lbTetrachloroethylene1.07E-061.07E-06lbToluene9.15E-042.65E-036.30E-016.33E-01lbVanadium7.08E-087.08E-08lbXylene (mixed Isomers)3.84E-061.94E-056.22E-016.22E-01lb72Zinc Compounds1.32E-018.05E-026.15E-018.27E-01lbVolatile Organic Compounds (VOC)5.05E-079.08E-029.09E-02lbTotal9.70E-011.58E+001.28E+011.54E+01lbSolid WasteMat. P&DFuel P&DFuel UseProcessTotalUnitsSludge2.52E+011.54E+011.17E+021.58E+02lbSolid Waste #15.50E+004.08E+014.63E+01lbDisposal Off-site, Subtitle DLandfill7.73E-035.78E-031.70E-023.05E-02lbDisposal Off-site, Subtitle CLandfill3.04E-032.27E-036.68E-031.20E-02lbDisposal On-site, Subtitle DLandfill1.34E-031.00E-032.94E-035.28E-03lbDisposal On-site, Subtitle Clandfill3.41E-042.55E-047.50E-041.35E-03lbTotal:3.08E+015.61E+011.17E+022.04E+02lbRaw Materials ExtractedFossil FuelMat. P&DFuel P&DFuel UseProcessTotalUnitsCoal1.08E+058.06E+059.14E+05BtuCrudeOil1.19E+074.73E+065.67E+077.33E+07BtuNaturalGas3.54E+042.64E+053.00E+05BtuNon-FossilFuelUranium4.72E-056.69E-026.69E-02lbWood3.79E-013.61E+003.99E+00lbWater ConsumptionMat. P&DFuel P&DFuel UseProcessTotalUnitsPublicSupply0.00E+00galRiver/Canal0.00E+00galSea0.00E+00galUnspecified2.27E+022.27E+02galWell0.00E+00galTotal:2.27E+022.27E+02galLand UseMat. P&DFuel P&DFuel UseProcessTotalUnitsUnknownacres73

### Appendix B

LCA and LCI Software Tools

Tool Vendor URL

BEES 3.0 NIST Building and Fire http://www.bfrl.nist.gov/oae/software/bees.html Research Laboratory

Boustead Model Boustead Consulting http://www.boustead-consulting.co.uk/products.htm

5.0

CMLCA 4.2 Centre of Environmental http://www.leidenuniv.nl/cml/ssp/software/cmlca/index.ht

Science ml

Dubo-Calc Netherlands Ministry of http://www.rws.nl/rws/bwd/home/www/cgiTransport, Public Works and bin/index.cgi?site=1&doc=1785 Water Management

Ecoinvent 1.2 Swiss Centre for Life Cycle http://www.ecoinvent.ch

Inventories Eco-Quantum IVAM http://www.ivam.uva.nl/uk/producten/product7.htm

EDIP PC-Tool Danish LCA Center http://www.lca-center.dk

eiolca.net Carnegie Mellon University http://www.eiolca.net

Environmental ATHENA TM Sustainable http://www.athenaSMI.ca Impact Indicator Materials Institute EPS 2000 Design Assess Ecostrategy Scandinavia http://www.assess.se/ System AB

GaBi 4 PE Europe GmbH and IKP http://www.gabi-software.com/software.html University of Stuttgart

GEMIS Öko-Institut http://www.oeko.de/service/gemis/en/index.htm

GREET 1.7 DOE’s Office of Transportation http://www.transportation.anl.gov/software/GREET/index.

html

IDEMAT 2005 Delft University of Technology http://www.io.tudelft.nl/research/dfs/idemat/index.htm

KCL-ECO 4.0 KCL http://www1.kcl.fi/eco/softw.html

LCAIT 4.1 CIT Ekologik http://www.lcait.com/01_1.html

LCAPIX v1.1 KM Limited http://www.kmlmtd.com/pas/index.html

MIET 3.0 Centre of Environmental http://www.leidenuniv.nl/cml/ssp/software/miet/index.htm

Science l

REGIS Sinum AG http://www.sinum.com/htdocs/e_software_regis.shtml

SimaPro 6.0 PRé Consultants http://www.pre.nl/simapro.html

SPINE@CPM Chalmers http://www.globalspine.com

SPOLD The Society for Promotion of http://lca-net.com/spold/ Life-Cycle Assessment

TEAM TM 4.0 Ecobalance http://www.ecobalance.com/uk_lcatool.php

Umberto ifu Hamburg GmbH http://www.ifu.com/en/products/umberto

US LCI Data National Renewable Energy http://www.nrel.gov/lci

Lab

BEES 3.0. Created by the National Institute for Standards and Technology (NIST) Building and Fire Research Laboratory, the BEES (Building for Enviro nmental and Economic Sustainability) software can be used for balancing the environmental and econom ic performance of building products. Version 3.0 of the WindowsTM-based decision support software, aimed at designers, builders, and product



### 74manufacturers, includes actual environmental and ec onomic performance data fo r 200 building products. BEES 3.0 can be downloaded free of charge from the NIST website.

Boustead Model 5.0. Created by Boustead Consulting, the B oustead Model is an extensive database in which data such as fuels and energy use, raw mate rials requirements, and solid, liquid, and gaseous emissions are stored. It also includes software which enables the user to manipulate data in the database and to select a suitable data presentation method from a host of options.

CMLCA 4.2. Created by the Centre of Environmental Science (CML) at Leiden University, Chain Management by Life Cycle Assessment (CMLCA) is a software tool that is intended to support the technical steps of the LCA procedure. The pr ogram can be downloaded from the CML website.

Dubo-Calc. The Netherlands Ministry of Transport, Pub lic Works, and Water Management has created a database containing LCI data of construction materials which are used in civil works. Data included are secondary data, derived from other databases, brought toge ther in a set to use with their software for designers.

Ecoinvent Database v1.2. The ecoinvent data v1.2 comprises more than 2700 datasets with global/European/Swiss coverage. About 1000 elementary flows are reported for each dataset, including emissions to air, water, and soil, mineral and fossil resources, and land use. Several actual and widespread impact assessment methods, namely th e cumulative energy demand, climate change, CML 2001, Eco-indicator 99, the ecological scarcity me thod 1997, EDIP 1997, EPS 2000, and Impact 2002+ are implemented. The ecoinvent data are availabl e through EMIS, GaBi, Regis, SimaPro, and Umberto and are importable into CMLCA, KCL-eco, and TEAM.

Eco-Quantum. Eco-Quantum is a calculating tool on the basis of LCA which serves actors in the building sector with quantitative info rmation on the environmental impact of buildings as a whole. The added value of Eco-Quantum in this context is the database with composition data of about 1000 building components. Eco-Quantum is available only in Dutch.

EDIP PC-Tool. Developed for the Danish EPA, the EDIP PC-Tool is a user friendly Windows application and database that supports the LCA process carried out according to the EDIP method. To carry out an LCA, detailed informa tion on all the processes and materials included in the life cycle of the product is needed. Therefore, the tool has been equi pped with a relational database, close in structure to the internationally recognized SPOLD format.

eiolca.net. Created by the Green Design Institute of Carnegie Mellon, this web site allows users to estimate the overall environmental impacts from producing a certain dollar amount of a commodity or

service in the United States. The database first was made publicly available in 1999; since then two major and several minor updates have been conducte d. The web-based model provides rough guidance on the relative impacts of different types of products , materials, services, or industries with respect to

resource use and emissions. The latest version is based on the 1997 industry benchmark input-output accounts compiled by the Bureau of Economic Analysis of the U.S. Department of Commerce. It incorporates emissions and resource use factors estim ated for all 491 sectors of the U.S economy, using publicly available electricity and fuel consumption data compiled by the U.S. Census Bureau, the U.S. Departments of Energy and Transportation, and environmental databases created by the U.S. EPA.

Environmental Impact Indicator. Developed by the Athena Institu te, the Estimator was prepared for architects, engineers, and researchers to get LCA answ ers about conceptual designs of new buildings or renovations to existing buildings. The Estimator ass esses the environmental implications of industrial, institutional, office, or both multi-unit and single-fam ily residential designs. The Estimator incorporates



### 75the Institute’s inventory databases that cover more than 90 structural and envelope materials. Released in 2002, it simulates over 1,000 different assembly combin ations and is capable of modeling 95 percent of the building stock in North America. Athena has al so developed databases for energy use and related air emissions for on-site construction of building assembli es; maintenance, repair and replacement effects though the operating life; and, demolition and disposal.

EPS 2000 Design System. Created by Assess Ecostrategy Scandinavia AB, EPS (Environmental Priority Strategies) is a life cycle impact assessment software for sustainable product development. A demo

version can be ordered from the website.

GaBi 4 Software System and Database . GaBi is supported jointly by PE Europe GmbH and IKP University of Stuttgart. Different versions are available from educational to professional use of Life Cycle Analysis to evaluate life cycle environmental, co st, and social profiles of products, processes and technologies. GaBi offers databases with worldwide coverage as well as Ecoinvent data. A demo version

is available for download.

GEMIS (Global Emission Model for Integrated Systems) . The Öko-Institut’s GEMIS is a life cycle analysis program and database for energy, material, and transport systems. The GEMIS database offers information on fossil fuels, renewables, processes for el ectricity and heat, raw materials, and transports.

The GEMIS database can be downloaded for free from the website.

GREET 1.7. The U.S. Department of Energy's Office of Transportation Technologies fuel-cycle model called GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) allows researchers to evaluate various engine and fuel combinations on a consistent fuel-cycle basis.

IDEMAT 2005. Created by Delft University of Technology, IDEMAT is a tool for material selections in the design process. It provides a database with technical information about materials, processes and components and allows the user to compare informat ion. A demo version can be downloaded from the

DTU website.

KCL-ECO 4.0. KCL-ECO can be used to apply LCA to complicated systems with many modules and flows. It includes allocation, impact assessment (characterization, normaliza tion, and weighting), and graphing features. A demo version can be downloaded from the KCL website.

LCAIT 4.1 . Offered by CIT Ekologik since 1992, LCAit has been used for the environmental assessment of products and processes. It includ es an impact assessment database, including characterization factors and weighting factors. A demo version can be downloaded from the CIT

website.

LCAPIX . Offered by KM Limited, the LCAPIX v1. 1 software combines LCA and Activity Based Costing (ABC) to help businesses assure environmental compliance while assuring sustained profitability. It allows for a quantitative measurement which can indicate the potential burden of any product. A licensing fee is required, but a demo version can be downloaded from the KM Ltd. website.

MIET 3.0. – Missing Inventory Estimation Tool. Created by the Centre of Environmental Science (CML), MIET is a Microsoft Excel spreadsheet that enables LCA practitioners to estimate LCI of missing flows that were truncated. MIET is based on the most up-to-date U.S. input-output table and

environmental data. MIET covers a bout 1,200 different environmental in terventions including air, water, industrial and agricultural soil emissions, and resour ce use by various industrial sectors. MIET can be

downloaded for free from the CML website after filling out a short questionnaire.



### 76REGIS. Developed by Sinum AG, REGIS is a software tool for creating corporate ecobalances and improving corporate environmental performance a ccording to ISO14031. A demo version can be

downloaded from the Sinum website.

SimaPro 6.0. Created by PRé Consultants, SimaPro is a professional LCA software tool that contains several impact assessment methods and several inve ntory databases, which can be edited and expanded without limitation. It can compare and analyze complex products with complex life cycles. A demo

version can be downloaded from th e web site link provided above.

SPINE@CPM. Maintained by IMI, Industrial Environmental Informatics at Chalmers University of Technology, LCI@CPM is a web portal for LCI information . T he portal provides the possibility to: search for specific LCI-data in the database; purchase LCI-data sets; and convert SPINE data sets into ISO/TS 14048 automatically. The database c ontains more than 500 data sets. SPINE@CPM is the ISO/TS

14048 version of the Swed ish national database. Some of the data sets in the database are reported as full flow-charts where each included process or transport is separately stored in the database. The data published in LCI@CPM are reviewed in order to en sure that the quality requirements according to

ISO/TS 14048 have been fulfilled.

SPOLD Data Exchange Software. The Society for Promotion of Life Cycle Development, a now defunct group, lives on in memory through this software that can be used to create, edit, import, and export data in the SPOLD '99 format. It can be downloaded from the 2.-0 LCA consultants website.

TEAM TM 4.0 . Offered by Pricewaterhouse Coopers Ec obilan Group (also known as Ecobalance), TEAMTM 3.0 is a professional tool for evaluating the life cycle environmental and cost profiles of products and technologies. It contains comprehe nsive database of over 600 modules with worldwide coverage. An online demo is available from the website.

Umberto. Created by the Institute for Environmental In formatics (ifeu) in Hamburg, Germany, Umberto serves to visualize material and energy flow systems. Data are taken from external information systems or are newly modeled and calculated.

US LCI Data. In May 2001, NREL and its partners created the U.S. Life-Cycle Inventory (LCI) Database to provide suppor t to public, private, and non-profit sect or efforts in developing product life cycle assessments and environmentally-oriented decision support systems and tools. The objective of the

U.S. LCI Database Project is to provide LCI data for commonly used materials, products and processes following a single data development protocol consistent with in ternational standards. Since the goal is to make the creation of LCIs easier, rather than to carry out full product LCIs, database modules provide data on many of the processes needed by others fo r conducting LCIs. However, the modules do not contain data characterizing the full life cycles of specific products. The data protocol is based on ISO 14048 and is compatible with the EcoSpold format. The LCI data are available in several formats: a streamlined spreadsheet, an EcoSpold format sp readsheet, an EcoSpold XML file, and a detailed spreadsheet with all the calculation details.



### 77

### Glossary

Accidental Emission An unintended environmental release.

Allocation Partitioning the input or output flows of a unit process to the product of

interest.

Attributional LCA An LCA that accounts for flows/impacts of pollutants, resources, and exchanges among processes within a chosen temporal window.

Background Data The background data include energy and materials that are delivered to the foreground system as aggregated data sets in which individual plants and operations are not identified.

Brines (oilfield) Wastewater produced along with crude oil and natural gas from oilfield operations.

By-Products an incidental product deriving from a manufacturing process or chemicalreaction, and not the primary product or service being produced. A byproduct can be useful and marketable, or it can have negative ecological

consequences.

Characterization Characterization is the second st ep of an impact assessment and characterizes the magnitude of the potential impacts of each inventory flow to its corresponding environmental impact.

Characterization Factor Factor derived from a characterization model which is applied to convert the assigned LCI results to the common unit of the category indicator.

Classification Classification if the first step of an impact assessment and is the process of assigning inventory out puts into specific environmental impact categories.

Composite Data Data from multiple facilities performing the same operation that have been combined or averaged in some manner.

Consequential LCA An LCA that attempts to account for flows/impacts that are caused beyond the immediate system in res ponse to a change to the system.

Co-Product A product produced together with another product.

Environmental Aspects Elements of a business’ products, actions, or activities that may interact

with the environment.

Environmental Loadings Releases of pollutants to the environment, such as atmospheric and

waterborne emissions and solid wastes.



### 78Equivalency Factor An indicator of the potential of each chemical to impact the given environmental impact category in comparison to the reference chemical

used.



### Equivalent Usage Ratio A basis for comparing two or more products that fulfill the same function. For example, comparing two containers based on a set volume of beverage to be de livered to the customer.

Facility-Specific Data Data from a particular operation within a given facility that are not combined in any way.

Foreground Data Data from the foreground system that is the system of primary concern to the analyst.

Fuel P&D Activities involved in the processing and delivery of fuel used to run a

process ; also called Precombustion Energy.

Functional Unit The unit of comparison that assures that the products being compared provide an equivalent level of function or service.

Green Technology A 

### technology that offers a more environmentally benign approach compared to an existing technology.

Impact Assessment The assessment of the environmental consequences of energy and natural resource consumption and waste releases associated with an actual or proposed action.

Impact Categories Classifications of human health and environmental effects caused by a product throughout its life cycle.

Impact Indicators Impact indicators measure the potential for an impact to occur rather than directly quantifying the actual impact.

Industrial System A collection of operations that t ogether perform some defined function.

Inventory Analysis The identification and quantifica tion of energy, resource usage, and environmental emissions for a particular product, process, or activity.

Interpretation The evaluation of the results of the inventory analysis and impact

assessment to reduce environmental releases and resource use with a clear understanding of the uncertainty and the assumptions used to generate the results.

Life Cycle Assessment A cradle-to-grave approach fo r assessing industrial systems that evaluates all stages of a product’s life. It provides a comprehensive view of the environmental aspects of the product or process.

Material P&D Activities involved in the processing and delivery of materials to a

process.



### 79Normalization Normalization is a technique for changing impact indicator values with differing units into a common, unitless format by dividing the value(s) by a selected reference quantity. This process increases the comparability of data among various impact categories.

Precombustion Energy The extraction, transportation, and processing of fuels used for power generation, including adjusting for in efficiencies in power generation and

transmission losses.

Product Life Cycle The life cycle of a product system begins with the acquisition of raw materials and includes bulk material processing, engineered materials production, manufacture and assembly, u se, retirement, and disposal of residuals produced in each stage.

Routine emissions Those releases that normally occur from a process, as opposed to accidental releases that proceed from abnormal process conditions.

Sensitivity Analysis A systematic evaluation process for de scribing the effect of variations of inputs to a system on the output.

Specific data Data that are characteristic of a particular subsystem, or process.

Stressors A set of conditions that may lead to an environmental impact. For example, an increase in greenhouse gases may lead to global warming.

System Flow Diagram A depiction of the inputs and outputs of a system and how they are

connected.

Weighting The act of assigning subjective, va lue-based weighting factors to the different impact categories based on their perceived importance or

relevance.



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