LCA Flashcards
• Product Life Cycle
Consecutive stages of a product system, divided into unit processes.
Product System
A collection of unit processes connected by intermediate flows. The goal of the system is to make product(s) with defined function(s).
• System boundaries
Defines the processes that will be included in the product system
• Life Cycle Assessment (LCA)
Compilation and evaluation of the inputs, outputs and environmental impacts of a product system throughout its lifecycle.
• Cut off
Specification of the level of detail an LCA will go to - the magnitude of environmental impact that is deemed insignificant for the study.
Stages of an LCA
Goal and Scope - Inventory Analysis - Impact Assessment - Interpretation
Reason for/purpose of Goal and Scope.
Needed to make the objectives, motivation, methods and assumptions of the LCA clear.
Difference between LCA and Risk Assessment
LCA assesses potential damage, risk assessments assess actual damage.
Types of AoP’s
Intrinsic (things we enjoy having) - Human wellbeing, Ecosystem Wellbeing, Natural and cultural heritage.
Instrumental (things we enjoy using) - Human productivity, Ecosystem productivity, Natural resources/man made capital.
AoP definition
Broad categories of areas of environmental concern.
Potential aims of LCA.
Explore - To identify areas of a product system where environmental impact can be reduced.
Compare - To compare the environmental impact of product systems.
Communicate - To make EPD’s (Environmental product declarations) or legislation i.e informing public or government.
What does the goal of LCA effect?
The scope - the method and area of protection.
Attributional LCA
Assessment of the environmental impact directly associated with a product. Based on average consumption of the product i.e. does not account for change in demand. Is useful for identifying hotspots in a product system.
Contributional LCA
Assessment of the environmental impact due to change in demand of reference flow. Burden is placed with whoever is responsible for the change in demand. Is useful for decision making guidance of different systems.
An LCA goal consists of
What - What is the purpose.
What for - What is the motivation.
Who for - Who is the audience.
An LCA scope consist of
Function(s) of product(s).
Functional unit - a quantitative representation of the products function.
Reference flow - what the product system needs to product to fulfil the functional unit.
Key parameters - Data needed to establish reference flow from functional unit.
System Boundaries - Cradle to Gate/Grave, Cut off point
Other - Assumptions, method of reporting
Necessary properties of chosen Functional Unit
Must not be biased in a comparative LCA, as it is the basis of comparison.
Must be clear on location, quantity and quality where appropriate.
Life cycle inventory definition
A list of the product systems elementary flows as the result of the production of 1 functional unit.
Elementary Flow
Material or energy crossing the system boundary that has not or will not be further processed by humans.
Intermediate flow
Flows between processes.
Method of producing LCI
Write the Product matrix (P=A/B) - rows consist of a substance/ product/ reference flow and columns consist of unit processes. A = technology matrix, B = intervention matrix.
Write the reference flow vector (f) - all entries will be empty bar the reference flow.
Find the scaling vector (s) from As = f -> A^(-1) f = s (Note, can check solution by As=f)
Find the elementary flows vector (g) using Bs = g.
Where can background and foreground data be found for an LCA?
Foreground - questionnaires, interviews.
Background - Ecoinvent.
Impact
A direct relationship between an elementary flow and an area of environmental concern. A significant externality of a product system.
Impact Category
A category representing several areas of environmental concern to which elementary flows can be assigned.
Impact category Classification
The assignment of environmantal issues to impact categories.
Impact Pathway Definition
Maps out the relationship between elementary flows and an area of environmental concern.
Characterisation Model
Quantitative model describing the impact pathway.
Characterisation Factors
Factors indicating the environmental impact associated with different elementary flows.
Category Indicator
Quantifiable representation of an impact category.
Midpoint Indicator
Have less uncertainty and objectivity because they are higher up the impact pathway, based more on scientific fact, but harder to interpret. Less appropriate for public.
Stages of Impact Pathway
Pressure - Fate - Exposure - Effect
End Point Indicator
Have greater uncertainty - more value based judgments have been made as it is lower down the impact pathway. Easy to interpret so more appropriate for public.
Aim of LCIA
To provide additional information so as to better understand the effect of the LCI on the environment.
Important qualities of Category Indicator.
Must represent all of the flows in an impact category. Must be easy to interpret, widely used, be clear about incidence, severity, duration.
Purpose of interpretation.
To summarise and evaluate LCA results in recommendations/conclusions. The iterative process begins here.
Aspects of LCA interpretation.
Consistency - are the goal/scope consistent?
Completeness - are the goal/scope met, are all indended data used?
Contribution - is one aspect of the result more significant than the rest.
Uncertainty
Sensitivity - to changes in functional unit, reference flows.
Conclusions and recommendations.
Normalisation
The referral of impact cores to a reference point to enable their comparison.
Should be done externally (e.g. per persons consumption/ average of that product) because internal normalisation can skew comparison between different units.
Grouping
The collation of impact categories into areas of the same units (inevitably AoP’s).
Weighting
Using weighting factors to emphasise certain impact categories/ results. Is not allowed to be applied if the report is for the public.
Difference between LCA and footprint
Footprint is based on one impact category, while LCA discusses all impact categories relative with the product (avoids burden shifting).
Functional Flow
A flow in a unit process that constitutes its function.
Multifunctional Processes
Unit process with more than one functional flow.
Allocation
Partitioning the inputs and outputs of a process between the product systems under study i.e. fairly allocating environmental burdens to different products.
Co-Production
The proportion of functional outputs from the system is variable. Partitioning can be applied based on physical relationships (using allocation factors). The system needs to be separated into subsystems with only one functional flow.
Joint Production
The proportion of functional outputs from the system is fixed. Partitioning can be applied based on value or mass of each product (using allocation factors). The system needs to be separated into subsystems with only one functional flow.
Describe the options that should be taken instead of allocation if a system has more than one product.
Divide the system into areas with only one functional flow - disaggregation.
Expand the systems functional unit to include other co-products - Expansion.
