Vehicle Scrappage & Efficiency Curves
My Dad is thinking of trading in his ten year old Renault Scenic under the government’s car scrappage scheme which launches today, and gives you £2000 to spend on a new car when you trade in your ten year old banger. The aim is to aid the economy by getting people spending, and to get older, more polluting, cars off the road in favour of clean new ones.
The scheme reminds me of when I was a design student and signed up for a course in “Environmentally Sensitive Design“, taught by Prof. Billett, which was the only final year option that had three hour lectures that felt like they flashed past in 30 minutes. One lesson that stuck in my mind was that the most environmentally sensitive behaviour is not always to keep stuff as long as possible – sometimes there is an environmentally optimum lifespan for a product.
This is often the case when a product consumes resources (like energy or water), and successive iterations of that product result in decreasing energy consumption. Ann Chalkley’s paper uses data about energy consumption of building and running a dishwasher and fits exponential curves to them, showing that the optimum lifespan of a dishwasher built in 1990 was 6.97 years, and predicting that the optimum lifespan of a dishwasher bought in 2009 will be 8.67 years.
It’s an interesting idea, but I’m not sure how universally applicable it is. I tried to work out the curves for my Dad’s Renault Scenic, but the fuel consumption for 1.9 diesel Scenics doesn’t follow the same pattern: the ’97 to ’99 model was 40mpg, the ’99 to ’03 did improve to 49mpg, but then the ’03 model spoilt it by dropping to 47mpg.
Which technologies are gradual enough to fit curves to? Can we design products that drop apart after their environmentally optimum lifespans and would we want to own them? Which cars are the period of ten years chosen by the government based on?