Common sense sometimes lets us down. For instance, common sense tells us that, if we improve energy efficiency, we will use less energy. Sadly, this truism does not always hold. In its place, we have Jevons’ Paradox, first expounded in 1865 by Professor William Stanley Jevons:
‘It is wholly a confusion of ideas to suppose that the economical use of fuel is equivalent to a diminished consumption. The very contrary is the truth.’
As a young man, Jevons spent the years 1854 to 1859 as an assayer at the Royal Mint’s NSW branch. He purchased this telescope in Sydney. A neat symbol of Jevons as both scientist and observer of human behaviour, it is on display in our exhibition ‘The curious economist: William Stanley Jevons in Sydney’. It is made of brass, and its outer draw (the cylinder into which the other six draws fit telescopically) is covered with shiny black material originally described in the museum’s database as ‘moulded black plastic tape, presumably added in the early twentieth century’. It is more likely that the material is baleen and that it was an original feature of the telescope. I wonder how many whales died to provide tough, flexible baleen to decorate telescopes or to make ‘whalebone’ stays for corsets, boots or umbrellas – plus whale oil that was burned to provide light.
Today we don’t harvest these materials from whales, but there is an urgent need to burn less fossil fuel (coal, oil and gas). Improving energy efficiency seems an obvious first step: quick, easy and relatively cheap. Thus it is vital that we understand why improved energy efficiency can lead to higher, rather than lower, energy consumption. Through such an understanding, I hope that we can escape the Paradox and truly reduce our energy use – and our energy bills.
On returning to Britain, Jevons wrote a book titled ‘The coal question’ to promote his ideas on resource use, economics and social progress. That book includes the words quoted above, the result of his consideration of improvements to steam engine efficiency, which had led to higher sales of steam engines and hence to higher coal use across the economy.
Jevons was referring explicitly to industrial use of energy, rather than to domestic use, which he stated was ‘undoubtedly capable of being cut down without other harm than curtailing our home comforts, and somewhat altering our confirmed national habits.’ He could not have imagined how energy-hungry our domestic habits would grow, with reticulated electricity allowing us to desire much more from the burning of coal than ‘the enjoyment of a good fire’.
There are many measures that we can take to reduce domestic use of energy today. These include insulating roofs and walls, installing energy-efficient lights and appliances, designing homes with eaves or awnings to shade windows in summer, and fitting heavy curtains and pelmets for use in winter.
But behaviour is just as important as design, and it is through our behaviour that we give in to, or overcome, Jevons’ Paradox. We can take the benefit of home insulation by not bothering to don clothes appropriate for the season, or as reduced energy use for heating and cooling. We can leave energy-efficient lights burning, telling ourselves it doesn’t matter because they use so little power, or reduce our energy use by switching them off when we don’t need them. In summer we can lower awnings to shade our windows each day, or turn up the aircon and chew up extra energy. In winter, those curtains are no use unless they’re drawn across our windows each evening. And we can reward ourselves each day with the enjoyment of a long hot shower, or save both water and energy by showering just long enough to get clean.
Studies have shown that people with small cars tend to drive further than those with large cars. Chicken and egg, or Jevons’ Paradox? It’s hard to tell, but if you’ve switched from a large car to a small one, have you actually used less fuel? How many of your purchasing and behavioural decisions are informed by a desire to reduce your carbon footprint?
If you would like to take part in discussion of energy issues, hear some interesting talks, compare our early electric car with a visiting group of modern ones, see other amazing energy-related objects, and enjoy fun energy-related activities, come along to the Powerhouse Discovery Centre’s ‘Power and Energy’ Open Day on Saturday 14 May.