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Step 7The life cycle analysis
SUMMARY:
This step gives an overview of the life cycle analysis (LCA) process.
It also shows how I used a software tool called ECO-it to performing "screening" LCA studies to compare the environmental impact of my choices for construction materials.
INTRO:
LCA is a method of evaluating the environmental impacts of the production, use, and disposal of products. While I will describe a linear process, in fact it is an iterative process. As information is revealed and the analysis progresses, more questions are raised, and opportunities for product improvement become apparent.
1. Goal definition and scope:
It is critical to develop a clear idea of the goals of your LCA study. This will guide every subsequent step, and keep you focused as you confront all of the questions and information.
I chose to perform an LCA study to help me understand the impact of my decisions, by:
-comparing between incandescent and compact fluorescent bulbs (energy consumption and perhaps packaging waste)
-comparing the relative impacts of production and disposal vs. use
-comparing the use of reclaimed vs. new materials
Determination of the functional unit is influenced by the goal. In my example, the functional unit that I chose was 3600 lumens (light output) for 10,000 hours (this is approximately equal to 3 hours per evening, 95% of the year or 347 days, for 10 years).
2. Constructing a process flow chart:
This task is the first step in what is called the inventory analysis.
The flow chart shows all of the phases in a product's life cycle: from resource extraction, through manufacturing and use, to disposal.
Theoretically, this can involve hundreds of steps for a single product. However, it is most useful if it provides an overview. As the analysis progresses, it will become clearer if particular process steps need to be detailed further.
In ECO-it, I created a bill-of-materials for the fixture. Each component was associated with its relevant manufacturing and use processes, as well as its likely methods of disposal.
3. Collecting the data:
For each process in the flow chart, all inflows and outflows must be quantified. These will describe raw materials, services, energy, in-process or finished products, waste, and emissions.
I measured the amount of each material that I used, estimated the amount of electricity I used with the power tools, and defined the power consumption of the different light bulb types. This data was an input into the project file in ECO-it.
4. Defining the system boundaries:
The boundaries that must be defined are:
-between the product system and the environment: i.e. the points at which materials become inputs and outputs
-between this product system and other systems: i.e. waste management systems
-between relevant and irrelevant processes: i. e. the production of tools
One of the decisions that I made was to exclude the consideration of light bulb production. Firstly, I was unable to get any data on the bulbs; secondly, the fact that 10 incandescent bulbs would be used for every CFL bulb was unlikely to improve the case for incandescent bulbs.
Another boundary decision was how to consider the PVC roofing material saved from landfill.
5. Processing data:
This is tabulation of the data, scaling the inputs and outputs to the functional unit, and grouping like impacts among different processes and materials.
It is also the last step in the inventory analysis.
In ECO-it, this is all done automatically.
6. Classification and characterization:
Different materials and processes create different types of impacts, such as global warming, ecotoxicity, acidification, and nutrification.
This step associates each item in the inventory analysis with these types of impacts.
Again, this creates quantitative data.
7. Valuation:
To enable comparisons between materials and processes with different impacts (like comparing apples to oranges), these impacts must be given relative weightings.
For example, in comparing the production of energy by coal or nuclear fission, one must value the relative harm created by global warming and that created by radioactive contamination. Otherwise, there is no way to decide which method of production is preferable.
The ECO-it software relies on the Eco-indicator 99 method to weight the various impacts. It boils down each material and process to a single number.
Other methods may be relevant, depending on your purpose.
8. Reporting and improvement assessment:
Reports are created to show the findings, according to your project's purpose.
Opportunities for improvement should be suggested by the reports, probably by first tackling the materials and processes having the largest impacts.
Notes about the LCA data
-All of the data comes from the database supplied with the software. This data is generic; it is based on European industry averages.
-The impact of electricity consumption is also based on the European average, and may be very different from your consumption. This depends completely upon how your electricity is generated: hydro-electric is very clean; coal-fired is very dirty.
References:
"Life Cycle Assessment: What It Is And How To Do It"
-United Nations Environment Programme, 1996
Software:
ECO-it (PRe Consultants B.V.)
their site
This step gives an overview of the life cycle analysis (LCA) process.
It also shows how I used a software tool called ECO-it to performing "screening" LCA studies to compare the environmental impact of my choices for construction materials.
INTRO:
LCA is a method of evaluating the environmental impacts of the production, use, and disposal of products. While I will describe a linear process, in fact it is an iterative process. As information is revealed and the analysis progresses, more questions are raised, and opportunities for product improvement become apparent.
1. Goal definition and scope:
It is critical to develop a clear idea of the goals of your LCA study. This will guide every subsequent step, and keep you focused as you confront all of the questions and information.
I chose to perform an LCA study to help me understand the impact of my decisions, by:
-comparing between incandescent and compact fluorescent bulbs (energy consumption and perhaps packaging waste)
-comparing the relative impacts of production and disposal vs. use
-comparing the use of reclaimed vs. new materials
Determination of the functional unit is influenced by the goal. In my example, the functional unit that I chose was 3600 lumens (light output) for 10,000 hours (this is approximately equal to 3 hours per evening, 95% of the year or 347 days, for 10 years).
2. Constructing a process flow chart:
This task is the first step in what is called the inventory analysis.
The flow chart shows all of the phases in a product's life cycle: from resource extraction, through manufacturing and use, to disposal.
Theoretically, this can involve hundreds of steps for a single product. However, it is most useful if it provides an overview. As the analysis progresses, it will become clearer if particular process steps need to be detailed further.
In ECO-it, I created a bill-of-materials for the fixture. Each component was associated with its relevant manufacturing and use processes, as well as its likely methods of disposal.
3. Collecting the data:
For each process in the flow chart, all inflows and outflows must be quantified. These will describe raw materials, services, energy, in-process or finished products, waste, and emissions.
I measured the amount of each material that I used, estimated the amount of electricity I used with the power tools, and defined the power consumption of the different light bulb types. This data was an input into the project file in ECO-it.
4. Defining the system boundaries:
The boundaries that must be defined are:
-between the product system and the environment: i.e. the points at which materials become inputs and outputs
-between this product system and other systems: i.e. waste management systems
-between relevant and irrelevant processes: i. e. the production of tools
One of the decisions that I made was to exclude the consideration of light bulb production. Firstly, I was unable to get any data on the bulbs; secondly, the fact that 10 incandescent bulbs would be used for every CFL bulb was unlikely to improve the case for incandescent bulbs.
Another boundary decision was how to consider the PVC roofing material saved from landfill.
5. Processing data:
This is tabulation of the data, scaling the inputs and outputs to the functional unit, and grouping like impacts among different processes and materials.
It is also the last step in the inventory analysis.
In ECO-it, this is all done automatically.
6. Classification and characterization:
Different materials and processes create different types of impacts, such as global warming, ecotoxicity, acidification, and nutrification.
This step associates each item in the inventory analysis with these types of impacts.
Again, this creates quantitative data.
7. Valuation:
To enable comparisons between materials and processes with different impacts (like comparing apples to oranges), these impacts must be given relative weightings.
For example, in comparing the production of energy by coal or nuclear fission, one must value the relative harm created by global warming and that created by radioactive contamination. Otherwise, there is no way to decide which method of production is preferable.
The ECO-it software relies on the Eco-indicator 99 method to weight the various impacts. It boils down each material and process to a single number.
Other methods may be relevant, depending on your purpose.
8. Reporting and improvement assessment:
Reports are created to show the findings, according to your project's purpose.
Opportunities for improvement should be suggested by the reports, probably by first tackling the materials and processes having the largest impacts.
Notes about the LCA data
-All of the data comes from the database supplied with the software. This data is generic; it is based on European industry averages.
-The impact of electricity consumption is also based on the European average, and may be very different from your consumption. This depends completely upon how your electricity is generated: hydro-electric is very clean; coal-fired is very dirty.
References:
"Life Cycle Assessment: What It Is And How To Do It"
-United Nations Environment Programme, 1996
Software:
ECO-it (PRe Consultants B.V.)
their site
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