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Friday, 25 July 2008
Lies, damn lies, but where do they get those statistics?
I was at an event the other week where a keynote speaker put up a picture of an ancient Landrover and said "This is my car. I'm eco-friendly as the emissions from vehicle production are much higher than those in use, so keeping it on the road is the right thing to do!""Rubbish" thought I (or words to that effect). But I gave him the benefit of the doubt and looked up some published stats, and as you can see the use phase comes to 80% and the manufacture 18%.
Toyota Gasoline Vehicle CO2 Emissions:
Driving 72%
Fuel production 8%
Vehicle production 6%
Material production 12%
Others 2%
But everybody knows this - who on earth told him the opposite?
Another one...
In May's ENDS Report, a Rosi Fieldson is quoted as saying "The more technologies that are put into a home, the higher the embodied carbon [ie that required to produce materials, components and build the house] becomes. Currently embodied energy is 15% of energy used over the building's life time .... In a zero carbon home this would rise to 80-90%."
Well either Dr Fieldson has been misquoted or she needs to go back to primary school to sort out her maths. It's a percentage! If you cut one part of the pie, the percentage taken by the other must go up because the two parts must add up to 100!
Strictly speaking the embodied energy of a zero carbon home should be 100% of lifetime energy, because the usage (non-renewable) energy is 0%. But it doesn't tell you whether the amount of embodied energy goes up or down...
I think I'm going to go and lie down in a darkened room...
Labels: energy, fun, life cycle assessment, rant
# posted by Gareth Kane : 09:30
0 Comments
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...
Labels: lca, life cycle assessment, product design
# posted by Gareth Kane : 09:56
1 Comments
A highly accessible, practical guide to those who want to introduce sustainability into their business or organization quickly and effectively.
