Friday, 4 January 2008
Lies, Damn Lies and Life Cycle Assessment...
For some time, I've been vaguely aware of some 'research' that purported to show that a GM Hummer was more eco-friendly than a hybrid Toyota Prius over its entire lifecycle. This puzzled me greatly so I decided to have a look myself.
In March 2007, a market research company called CNWMR published a report called 'Dust To Dust' which appeared to show that, taking into consideration energy over the whole lifecycle, the energy cost of a Prius was $3.25 per mile whereas the Hummer H3 was only $1.949 per mile (dig the precision). This caused jubilation amongst the reactionary press and blogosphere and outrage amongst their progressive counterparts.
While many of the latter produced long lists and reports of what was wrong with the CNWMR analysis, I personally believe there is one big fatal flaw.
CNWMR factored in the different driver behaviour of the two vehicles - an average of 100 000 miles across its lifetime for the Prius and 400 000 ish for the Hummer. The Prius does have a higher energy cost to build (partly due to the battery, partly because it is unique so cannot share facilities with other models), so this skews the analysis heavily against the Prius as the smaller build energy for the Hummer is spread more thinly against all those miles.
To put it in layman's terms the argument is: the Prius is more damaging because its drivers drive less.
Or conversely: if you drive more then your vehicle is more eco-friendly!
Ludicrous!
This clearly demonstrates the WYGIWYN (what you get is what you need) effect associated with life cycle assessments. If LCA is to be used to make clear judgements between products then standardised methods are required (as with fuel efficiency or energy labelling) to ensure that this sort of idiocy is not given the oxygen of publicity that I've just given it!
In March 2007, a market research company called CNWMR published a report called 'Dust To Dust' which appeared to show that, taking into consideration energy over the whole lifecycle, the energy cost of a Prius was $3.25 per mile whereas the Hummer H3 was only $1.949 per mile (dig the precision). This caused jubilation amongst the reactionary press and blogosphere and outrage amongst their progressive counterparts.
While many of the latter produced long lists and reports of what was wrong with the CNWMR analysis, I personally believe there is one big fatal flaw.
CNWMR factored in the different driver behaviour of the two vehicles - an average of 100 000 miles across its lifetime for the Prius and 400 000 ish for the Hummer. The Prius does have a higher energy cost to build (partly due to the battery, partly because it is unique so cannot share facilities with other models), so this skews the analysis heavily against the Prius as the smaller build energy for the Hummer is spread more thinly against all those miles.
To put it in layman's terms the argument is: the Prius is more damaging because its drivers drive less.
Or conversely: if you drive more then your vehicle is more eco-friendly!
Ludicrous!
This clearly demonstrates the WYGIWYN (what you get is what you need) effect associated with life cycle assessments. If LCA is to be used to make clear judgements between products then standardised methods are required (as with fuel efficiency or energy labelling) to ensure that this sort of idiocy is not given the oxygen of publicity that I've just given it!
Labels: dust to dust, hummer, lca, prius
Thursday, 23 August 2007
Is life too short for life cycle assessment?
One phrase that immediately makes me suspicious is "A Life Cycle Assessment has shown that...".
If you haven't come across Life Cycle Assessment (LCA) before, it is a structured method of collating all the inputs and outputs over a product's life cycle and combining them into a single score. The results can be used either to identify the key environmental impacts over the life cycle, or to decide which of a number of products are most eco-friendly.
This sounds great until you actually try it. I've done two to a greater or lesser extent and reviewed many case studies. The reasons why I don't particularly want to do any more are:
1. Time, cost & effort - it takes ages to hunt down information and usable generic data is hard to come by. One major electronics manufacturer told me that they budget £10 000 per component for LCA.
2. Assumptions on the life cycle - so-called durable products tend to get binned when their owner decides to rather than when they actually break down and die. A mobile phone will happily last 10 years with a battery upgrade, but I replaced my last one after 4 years when I needed a new battery and I was fed up with younger colleagues laughing at it. So all those questions on how long the product will last, how often it will be used etc are very hard to predict and, as I discovered in my MPhil on the subject, it is these factors that often have most influence on LCA results.
3. WYGIWYN - What You Get Is What You Need - the tendency for LCAs to mysteriously back the product of the company sponsoring the LCA over its rivals...
4. The tendency for independent LCAs to find no statistical difference between completely different product systems, for example the paper/plastic bag and real/disposable nappy debates.
5. LCAs can't do some impacts very well - like losing the last tiger, or waste to landfill.
6. They only give you information about the current product - the time and money might have been better spent on finding a breakthrough solution.
Don't get me wrong, I'm not against whole life cycle thinking, but I think practitioners are kidding themselves if they honestly believe LCA gives them the answer. An answer maybe...
If you haven't come across Life Cycle Assessment (LCA) before, it is a structured method of collating all the inputs and outputs over a product's life cycle and combining them into a single score. The results can be used either to identify the key environmental impacts over the life cycle, or to decide which of a number of products are most eco-friendly.
This sounds great until you actually try it. I've done two to a greater or lesser extent and reviewed many case studies. The reasons why I don't particularly want to do any more are:
1. Time, cost & effort - it takes ages to hunt down information and usable generic data is hard to come by. One major electronics manufacturer told me that they budget £10 000 per component for LCA.
2. Assumptions on the life cycle - so-called durable products tend to get binned when their owner decides to rather than when they actually break down and die. A mobile phone will happily last 10 years with a battery upgrade, but I replaced my last one after 4 years when I needed a new battery and I was fed up with younger colleagues laughing at it. So all those questions on how long the product will last, how often it will be used etc are very hard to predict and, as I discovered in my MPhil on the subject, it is these factors that often have most influence on LCA results.
3. WYGIWYN - What You Get Is What You Need - the tendency for LCAs to mysteriously back the product of the company sponsoring the LCA over its rivals...
4. The tendency for independent LCAs to find no statistical difference between completely different product systems, for example the paper/plastic bag and real/disposable nappy debates.
5. LCAs can't do some impacts very well - like losing the last tiger, or waste to landfill.
6. They only give you information about the current product - the time and money might have been better spent on finding a breakthrough solution.
Don't get me wrong, I'm not against whole life cycle thinking, but I think practitioners are kidding themselves if they honestly believe LCA gives them the answer. An answer maybe...
Labels: lca, life cycle assessment, product design
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