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                            What's LCA ?


1. General idea of LCA

A systematic set of procedures for compiling and examining the inputs and outputs of materials and energy and the associated environmental impacts directly attributable to the functioning of a product or service system throughout its life cycle. this method will freely set the establishment of object broadly to simple product and complex system. this technique's objective is offer a material of judgement of decision-making which reduce environmental road by human's diverse activity. in this respect LCA is effectively control local and also Earth environmental problem.


2. structural elements of LCA

ISO committee continuously discuss about LCA's methodology, and the basic component are as followings.

1) goal and scope definition
2) inventory analysis
3) impact assessment
4) interpretation
5) reporting
6) critical review

Here are more detail,

1) stage 1 : goal and scope definition
In the stage, one must clearly represent LCA's goal, scope definition(content of survey) and object and then show diverse outcome in scope. Requirements of LCA's goal and definition are as followed.


Goal of LCA
  • reason of LCA
  • object of report
  • application of LCA's outcome

　

Scope of LCA
  • LCA object's clearly definition of product or service (system)
  • product name, function and functional unit, boundary(lca's analysis scope)
  • required data's scope, data quality
  • precondition, condition
  • setting of considered environmental effect assessment item and assessment method
  • distribution method of environmental road about product
  • by-product and recycling


2) stage 2 : inventory analysis
this stage plays key role in LCA. an inventory analysis identifies and quantifies inputs and outputs. in object's life cycle, this stage tracks material, energy, and product through system and construction of environmental burden item. in this stage, allocation problem is important but not yet installed united method.


3) stage 3 : impact assessment
from the inventory analysis, this stage is environmental analysis and assessment stage about each environmental category from environmental load item's outcome. sometimes, the total category is evaluated to determine the environmental effects. the followings include several aspects of assessment boundary mainly earth environmental problem.

  • resource/energy consumption quantity
  • acid rain
  • sea contamination
  • loss of wild animals
  • global warming
  • atmosphere/water pollution
  • deforestation
  • human health risks
  • stratospheric ozone depletion
  • hazardous wastes
  • desertification
  • land use


4) stage 4 : interpretation
this is evaluate or analysis stage using individually or synthetically outcome of inventory analysis and impact assessment. Interpretation is a conclusion of LCA object and scope.


5) reporting
LCA survey conclusion obtain from number 1) ~ 4) arrange report type and reporting.


6) critical review
review is guarantee about obey ISO regulation, scientifically reasonable or application method and data that is suitable to object and logical.

　

3. methodology of LCA

ISO adapt ISO 14000 series. in this ground , city element study like architecture and civil engineering move to product and material LCA. energy consumption include product or system impact and environmental load LCA has three parts ;

  • Process analysis
  • Input-output analysis
  • Combine process and input-output analysis

　
  Process analysis

this process concretely investigate each product. it divide product process or material from design-manual and an estimate and investigate each product how to product and deposit. this process mainly applied product. in order to use this process, oversea progress database like money-oriented information.
this process progressed concentrically SETAC and U. S. EPA (fava, 1991) now. this process was considered to apply ISO 14000s (ISO, 1998) process analysis which generally considered LCA methology has three parts - "assessment", "analysis", "improvement".
in process analysis, when inspect each product of process, it is important to determine scope of analysis. each step divide three part assessment, analysis, and improvement. summary of those method is following.
"assessment" stage is divide obviously both recycling stage's and environmental output of product or process, but certain product or process have too much total network or sub-use. it is difficult to qualified total process because therefore, this process generally focus on merely several process or material that thought to be important.
in "analysis" stage investigate environmental burden degree or condition which assessed. this stage draw conclusion from the "assessment" outcome.
"improvement" stage draw how to reduce environmental burden associated with product system or process.
process analysis clearly define entity and cause of environmental burden. it is possible quantitative analysis and assessment of environmental burden associated with each product's produce, distribution, and consumption. this process leave room for improvement when conduct LCA. LCA has been criticized for several problems.

  • This process has a limit and can not include all processes
  • There is lack of comprehensive data for LCA
  • Data reliability is questionable
  • This process is difficult and complicate in calculating the conversion factor of each Material and parts which produce complex industrial system
  • Problem defining boundaries for LCA is controversial and arbitrary. different boundary definition may lead to different results
  • It is unclear how reliable LCA outcome can be achieved with additional system boundary
  • LCA is too expensive and slow for application in the design process
  • There is no single LCA method that is universally agreed upon and acceptable
  • Conventional, SETAC-type LCA usually ignore generally indirect economic and environmental effect
  • process analysis LCA study has not immense environmental burden's outcome but describe merely several effect
  • Equally credible analyses can make qualitatively different results, consequently, the results of particular LCA cannot be defended scientifically
  • Modeling a new product or process is difficult and expensive
  • LCA can not capture the dynamics of changing markets and technologies
  • LCA results may be inappropriate for use in eco-labeling because of differences in interpretation of results
  • Institution and company has there own LCA method. therefore, reliable and transparent common LCA method is need


   Input-output analysis

Input-output model in its most basic form consists of a system of linear equations, each one of which describes the distribution of an industry's product through the economy. it also called input-output tables. input-output frameworks has been extended to deal more explicitly.
The advantages of input-output analysis are :

  • It is possible to enlarge system boundary
  • Analysis outcome is objective
  • Input-output analysis is a trusted model
  • Analysis and Calculating time is very short compared with process analysis
  • Efforts in analytic process are relatively effective
  • economic input-output analysis is a tried and flexible method

but this method is insufficient to analysis each product or technical analysis because this process makes simplification and generalization about industrial structure and process activity. production in this system operates under what is known as constant returns to scale. those items which didn't show in table like new technology and recycling is not analysis.
Reviewing environmental pollution burden should consider stages total earth size from domestic to international. but every country does not have input-output table.


   Combined process and input-output analysis

The benefits of this method are able to separate detailed part division and inclusive. On the other side, this method's defect, like process analysis, is deficient the reliability because of its specific process condition. this method also much amount of work draw precision associated with design information and an estimate.