In my last semester in graduate school, I took a class on
LCA. My semester project was a comparison of two different products that use a
stream of gas for dusting purposes (a gas duster and bulb duster). Here is a
summary of my project. My goal in this blog post is to give an example of one
way to do LCA. I also hope to link some of the terminology to a separate blog
post for definitions and explanations.
Part one of this blog post includes the general information for
the study.
Overview of Materials
and Methods
Two products were analyzed in this assessment: 3M DustRemover (10 oz) and Giottos AA1900 Rocket Air Blaster (Large).
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Figure 1. Dusters analyzed in this assessment with their
retail packaging (“gas duster” on the left and “bulb duster” on the right.
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The tools used to conduct this analysis included a kitchen
scale, measuring tape, stopwatch, SimaPro 7.3 software, and Microsoft Excel
software. Each product was disassembled
and weights and/or dimensions were taken (including packaging) with the kitchen scale and measuring tape. For the gas
duster, the time to empty the canister was measured using a stopwatch. The guidelines in ISO
14040:2006 were used for conducting the LCA. SimaPro 7.3 software was used to
conduct the actual LCA: measurement data were entered into SimaPro, software-embedded environmental
data (process data) were chosen within SimaPro, and all the data were then analyzed
(normalization) by SimaPro. The results were then exported from SimaPro into Excel. Excel was used to make the functional unit adjustment to the
SimaPro results and to create the data tables and graphs.
Goal
The goal of this assessment is to compare the life cycle
impact of each duster. The intended audience for this assessment is Phillip
White’s Problem Solving with LCA class. The
results of this study have not been peer-reviewed and are not intended to be
used in decision-making processes.
Functional Unit and
Lifetime of Each Product
The functional unit in this study is product typical amount
of time spent dusting, which is arbitrarily set at two minutes. The chosen
frequency of a two-minute dusting-session is once per month.
Gas Duster
Through experimentation, I found that the gas duster lasted
for 25 minutes before running out of gas. This experiment was generally
conducted by using a stopwatch while using the duster to dust various things.
Because the gas in the duster “runs out”, its lifetime is
calculated from the number of minutes it lasts (25 minutes) and the expected
use pattern (two minutes per month):
Lifetimegas_duster = 25 min dusting x (1 dust session/2 min dusting) x (1 year/12 dust sessions) = 1.042 years.
The calculation for the service lifetime for the gas duster
is just the number of minutes it lasts (25 minutes)
adjusted for the functional unit of two minutes of dusting per dusting-session:
Service Lifetimegas_duster
= 25 min dusting x (1 dust session/2 min dusting) = 12.5 dusting-sessions in the lifetime of the gas
duster.
Bulb Duster
The bulb duster is a different case from the gas duster. The
air in the bulb duster does not “run out”, but the bulb duster will not last
forever. The rubber will wear out or the consumer will stop using it or replace
it with a different duster after a while.
In this study it is assumed that the bulb duster will be
discarded after eight years of use. Therefore, the lifetime of the bulb duster
is straightforward:
Lifetimebulb_duster = 8
years.
For the bulb duster, the expected use pattern (two minutes
per month) is needed to calculate the service lifetime along with the expected
lifetime of the product (eight years). Therefore, the service lifetime for the
bulb duster is as follows:
Service Lifetime bulb_duster = (2 min dusting/1 month) x (12 months/ 1 year) x 8 years x (1 dust session/2 min dusting) = 96 dusting-sessions in the lifetime of the bulb duster.
Data and Methods Used
in SimaPro
SimaPro 7.3 was used for this analysis. The impact
assessment method chosen was CML 2 Baseline 2000 v 2.04 (excluding marine ecotoxicity),
with 1995 Global normalization and no weighting. CML 2 was used because it uses
scientifically based midpoint values and does not have the complexity of
choosing cultural perspectives for characterization (Recipe method). The
following process data from SimaPro was used: ecoinvent system processes,
Industry data 2.0, and ELCD. The only case where the process data match up
geographically with the life cycle is in the case of the electricity data for
China (for manufacturing of the products).
Interpretation in this analysis includes contribution analysis
(normalized percent contributing elements and impact categories) and
sensitivity analysis.
Geography and Time
Period Used
The locations of manufacturing and distribution were chosen
based on information on the product label, company website, and general
knowledge about manufacturing. For example Guangdong Province was chosen as the
manufacturing location for manufacturing in China, because it is known as a
manufacturing hub for consumer goods. The chosen location for consumption and
disposal was the USA.
The earliest date of the impact assessment method used is
1995. The unit process data are assumed to be recent (within the last ten
years). The bulb duster has a lifetime of eight years. Therefore, the time
period of the study starts in 1995 with the date of the characterization method
and ends at the end of the lifetime of the bulb duster – eight years from the
present, which is 2020.
In the next section, Part II, all of the data used are given
and the LCA system boundary is described.
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