ASQ ISO 14041-1998 Environmental management - Life cycle assessment - Goal and scope definition and inventory analysis.pdf

1、ANSI/ISO 14041-1998AMERICAN NATIONAL STANDARDEnvironmental management Life cycle assessment Goal and scope definition and inventory analysisAMERICAN SOCIETY FOR QUALITYP.O. BOX 3005MILWAUKEE, WI 53201-3005ANSI/ISO 14041-1998AMERICAN NATIONAL STANDARDEnvironmental managementLife cycle assessment Goal

2、 and scope definition and inventory analysisApproved as an American National Standard by:NSF International (NSF)American Society for Testing formulate the goal and scope of the study, define and model the systems to be analysed, collect the data andreport the results of an LCI; establish a baseline

3、of environmental performance for a given product1)system by quantifying the use ofenergy flows and raw materials and emissions to air, water and land (environmental input and output data)associated with that system both for the whole system but also broken down by unit process; identify those unit p

4、rocesses within a product system where the greatest use of energy flows, raw materials andemissions occur with a view to making targeted improvements; provide data for subsequent use to help define ecolabelling criteria; help to set policy options, e.g. concerning procurement.This list is not exclus

5、ive, although it does summarize the primary reasons why LCI studies are carried out.Complementary International Standards ISO 14042 and ISO 14043 concerning further phases of LCA are underpreparation (see Bibliography). A Technical Report providing examples of practice in carrying out an LCI as amea

6、ns of satisfying certain provisions of ISO 14041 is also under preparation.1) In this International Standard, the term “product“ used alone is synonymous to “product or service“.(This page intentionally left blank)ANSI/ISO 14041-19981Environmental management Life cycle assessment Goal and scope defi

7、nition and inventory analysis1 ScopeThis International Standard in addition to ISO 14040 specifies the requirements and the procedures necessary forthe compilation and preparation of the definition of goal and scope for a Life Cycle Assessment (LCA), and forperforming, interpreting and reporting a L

8、ife Cycle Inventory analysis (LCI).2 Normative referenceThe following normative document contains provisions which, through reference in this text, constitute provisions ofthis International Standard. For dated references, subsequent amendments to, or revisions of, this publication donot apply. Howe

9、ver, parties to agreements based on this International Standard are encouraged to investigate thepossibility of applying the most recent edition of the normative document indicated below. For undated references,the latest edition of the normative document referred to applies. Members of ISO and IEC

10、maintain registers ofcurrently valid International Standards.ISO 14040:1997, Environmental management Life cycle assessment Principles and framework.3 Terms and definitionsFor the purposes of this International Standard, the terms and definitions given in ISO 14040 and the followingapply.3.1ancillar

11、y inputmaterial input that is used by the unit process producing the product, but does not constitute a part of the productEXAMPLE A catalyst.3.2coproductany of two or more products from the same unit process3.3data qualitycharacteristic of data that bears on their ability to satisfy stated requirem

12、ents3.4energy flowinput to or output from a unit process or product system, quantified in energy unitsNOTE Energy flow that is input may be called energy input; energy flow that is output may be called energy output.ANSI/ISO 14041-199823.5feedstock energyheat of combustion of raw material inputs, wh

13、ich are not used as an energy source, to a product systemNOTE It is expressed in terms of higher heating value or lower heating value.3.6final productproduct which requires no additional transformation prior to its use3.7fugitive emissionuncontrolled emission to air, water or landEXAMPLE Material re

14、leased from a pipeline coupling.3.8intermediate productinput to or output from a unit process which requires further transformation3.9process energyenergy input required for a unit process to operate the process or equipment within the process excluding energyinputs for production and delivery of th

15、is energy3.10reference flowmeasure of the needed outputs from processes in a given product system required to fulfill the function expressedby the functional unit3.11sensitivity analysissystematic procedure for estimating the effects on the outcome of a study of the chosen methods and data3.12uncert

16、ainty analysissystematic procedure to ascertain and quantify the uncertainty introduced into the results of a life cycle inventoryanalysis due to the cumulative effects of input uncertainty and data variabilityNOTE Either ranges or probability distributions are used to determine the uncertainty in t

17、he results.4 LCI components4.1 GeneralThis clause outlines the key terminology and components of a life cycle inventory analysis.4.2 Product systemA product system is a collection of unit processes connected by flows of intermediate products which perform oneor more defined functions. Figure 1 shows

18、 an example of a product system. A product system description includesunit processes, elementary flows, and product flows across the system boundaries (either into the system or out ofthe system), and intermediate product flows within the system.The essential property of a product system is characte

19、rized by its function, and cannot be defined solely in terms ofthe final products.ANSI/ISO 14041-19983Figure 1 Example of a product system for life cycle inventory analysis4.3 Unit processProduct systems are subdivided into a set of unit processes (see Figure 2). Unit processes are linked to oneanot

20、her by flows of intermediate products and/or waste for treatment, to other product systems by product flows,and to the environment by elementary flows.Examples of elementary flows entering the unit process are crude oil in ground and solar radiation. Examples ofelementary flows leaving the unit proc

21、ess are emissions to air, emissions to water and radiation. Examples ofintermediate product flows are basic materials and subassemblies.Figure 2 Example of a set of unit processes within a product systemANSI/ISO 14041-19984Dividing a product system into its component unit processes facilitates the i

22、dentification of the inputs and outputs ofthe product system. In many cases, some of the inputs are used as a component of the output product, while others(ancillary inputs) are used within a unit process but are not part of the output product. A unit process also generatesother outputs (elementary

23、flows and/or products) as a result of its activities. The boundary of a unit process isdetermined by the level of modelling detail that is required to satisfy the goal of the study.Because the system is a physical system, each unit process obeys the laws of conservation of mass and energy.Mass and e

24、nergy balances provide a useful check on the validity of a unit process description.4.4 Data categoriesCollected data, either measured, calculated or estimated, are utilised to quantify the inputs and outputs of a unitprocess. The major headings under which data can be classified include: energy inp

25、uts, raw material inputs, ancillary inputs, other physical inputs; products; emissions to air, emissions to water, emissions to land, other environmental aspects.Within these headings, individual data categories shall be further detailed to satisfy the goal of the study. Forexample, under emissions

26、to air, data categories such as carbon monoxide, carbon dioxide, sulfur oxides, nitrogenoxides, etc. can be separately identified. Further description of such data categories is provided in 5.3.4.4.5 Modelling product systemsLCA studies are conducted by developing models that describe the key elemen

27、ts of physical systems. It is often notpractical to study all the relationships between all the unit processes in a product system, or all the relationshipsbetween a product system and the system environment. The choice of elements of the physical system to bemodelled is dependent on the definition

28、of the goal and scope of the study. The models used should be describedand the assumptions underlying those choices should be identified. Further description is provided in 5.3.3 and5.3.5.5 Definition of goal and scope5.1 GeneralThe goal and scope of an LCA study shall be clearly defined and consist

29、ent with the intended application. Therequirements of ISO 14040:1997, 5.1 apply.5.2 Goal of the studyThe goal of an LCA study shall unambiguously state the intended application, the reasons for carrying out the studyand the intended audience, i.e. to whom the results of the study are intended to be

30、communicated.5.3 Scope of the study5.3.1 GeneralThe scope of the study shall consider all relevant items in accordance with ISO 14040:1997, 5.1.2It should be recognized that an LCA study is an iterative technique, and as data and information are collected,various aspects of the scope may require mod

31、ification in order to meet the original goal of the study. In some cases,the goal of the study itself may be revised due to unforeseen limitations, constraints or as a result of additionalinformation. Such modifications, together with their justification, should be duly documented.ANSI/ISO 14041-199

32、855.3.2 Function, functional unit and reference flowIn defining the scope of an LCA study, a clear statement on the specification of the functions (performancecharacteristics) of the product shall be made.The functional unit defines the quantification of these identified functions. The functional un

33、it shall be consistent withthe goal and scope of the study.One of the primary purposes of a functional unit is to provide a reference to which the input and output data arenormalized (in a mathematical sense). Therefore the functional unit shall be clearly defined and measurable.Having defined the f

34、unctional unit, the amount of product which is necessary to fulfill the function shall be quantified.The result of this quantification is the reference flow.The reference flow is then used to calculate the inputs and outputs of the system. Comparisons between systemsshall be made on the basis of the

35、 same function, quantified by the same functional unit in the form of their referenceflows.EXAMPLE In the function of drying hands, both a paper towel and an air-dryer system are studied. The selected functionalunit may be expressed in terms of the identical number of pairs of hands dried for both s

36、ystems. For each system, it is possibleto determine the reference flow, e.g. the average mass of paper or the average volume of hot air required for one hand-dry,respectively. For both systems, it is possible to compile an inventory of inputs and outputs on the basis of the reference flows.At its si

37、mplest level, in the case of paper towel, this would be related to the paper consumed. In the case of the air-dryer, thiswould be largely related to the energy input to the air dryer.If additional functions of any of the systems are not taken into account in the comparison of functional units, thent

38、hese omissions shall be documented. For example, systems A and B perform functions x and y which arerepresented by the selected functional unit, but system A also performs function z, which is not represented in thefunctional unit. It shall then be documented that function z is excluded from this fu

39、nctional unit. As an alternative,systems associated with the delivery of function z may be added to the boundary of system B to make the systemsmore comparable. In these cases, the processes selected shall be documented and justified.5.3.3 Initial system boundariesThe system boundaries define the un

40、it processes to be included in the system to be modelled. Ideally, the productsystem should be modelled in such a manner that inputs and outputs at its boundary are elementary flows. In manycases there will not be sufficient time, data, or resources to conduct such a comprehensive study. Decisions s

41、hallbe made regarding which unit processes shall be modelled by the study and the level of detail to which these unitprocesses shall be studied. Resources need not be expended on the quantification of such inputs and outputs thatwill not significantly change the overall conclusions of the study.Deci

42、sions shall also be made regarding which releases to the environment shall be evaluated and the level of detailof this evaluation. In many instances those system boundaries defined initially will subsequently be refined on thebasis of the outcome of the preliminary work (see 6.4.5). The criteria use

43、d to assist in the choice of inputs andoutputs should be clearly understood and described. Further guidance on this process is provided in 5.3.5.Any decisions to omit life cycle stages, processes or inputs/outputs shall be clearly stated and justified. The criteriaused in setting the system boundari

44、es dictate the degree of confidence in ensuring that the results of the study havenot been compromised and that the goal of a given study will be met.Several life cycle stages, unit processes and flows should be taken into consideration, e.g.: inputs and outputs in the main manufacturing/processing

45、sequence; distribution/transportation; production and use of fuels, electricity and heat; use and maintenance of products; disposal of process wastes and products; recovery of used products (including reuse, recycling and energy recovery);ANSI/ISO 14041-19986 manufacture of ancillary materials; manu

46、facture, maintenance and decommissioning of capital equipment; additional operations, such as lighting and heating; other considerations related to impact assessment (if any).It is helpful to describe the system using a process flow diagram showing the unit processes and theirinterrelationships. Eac

47、h of the unit processes should be initially described to define: where the unit process begins, in terms of the receipt of raw materials or intermediate products; the nature of the transformations and operations that occur as part of the unit process; and where the unit process ends, in terms of the

48、 destination of the intermediate or final products.It should be decided which input and output data should be traced to other product systems, including the decisionsabout allocation. The system should be described in sufficient detail and clarity to allow another practitioner toduplicate the invent

49、ory analysis.5.3.4 Description of data categoriesThe data required for an LCA study are dependent on the goal of the study. Such data may be collected from theproduction sites associated with the unit processes within the system boundaries, or they may be obtained orcalculated from published sources. In practice, all data categories may include a mixture of measured, calculated orestimated data. Subclause 4.4 outlines the major headings for the inputs and outputs that are quantified for eachunit process within the systems boundary. These data categories