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When the rebound just gets harder and harder

Improving energy efficiency is often cited as the key to a more sustainable society. But this equation has a crucial snag: a paradox phenomenon known as ‘rebound’.

In his 1865 book, “The Coal Question”, British economist and philosopher William Stanley Jevons made a remarkable observation. Although the steam engine introduced by James Watt had functioned far more efficiently with coal than its predecessor model by Thomas Newcomen had done, coal consumption in England had actually increased sharply upon the introduction of Watt’s steam engine. Jevons’ brilliant final conclusion: coal consumption was not increasing despite the fact that the new steam engines worked more efficiently, but because they did so. This phenomenon is best known as the ‘rebound effect’.

“If you can produce something more economically and using fewer resources thanks to more efficient production, then it also becomes cheaper,” explains Marina Fischer-Kowalski, founder and head of the Institute of Social Ecology in Vienna. “That means people have money left over either to buy more of that product or something else, which then consumes just as many resources. In the end, therefore, you make absolutely no saving at all. Instead, you get the same level of consumption if you’re lucky, and if you’re unlucky you get an even higher level.”

One example: if someone decides to replace their old light bulbs with modern low-energy bulbs, it initially looks like an enormous amount of energy is being saved. But efficiency is not the same thing as economy. Since the new lamps consume much less electricity, the temptation increases to buy oneself chic outdoor lighting or even more elegant recessed lighting. And because the new low-energy light bulbs are so efficient, of course, you can leave them on for longer, even if you may not be in the room at the time – the net result being that electricity consumption is suddenly no lower than it was before. In this case, we talk about a ‘direct rebound’.

In an indirect rebound, energy is saved thanks to the increase in efficiency, but the money saved as a result is immediately expended again on another energy-guzzler. “When people fly to the Caribbean because their household energy consumption has gone down so much, they have found a new way of spending their money that is particularly damaging to the environment,” Marina Fischer-Kowalski explains.

In general, though, we can’t yet say what the actual impact of these rebound effects is. Depending on the technology and device involved, rebound effects immediately guzzle 10-80 percent of any savings made, according to the result of a survey carried out on behalf of the European Commission.

There are also some areas where rebound effects hardly apply at all. A survey of 98 volunteers showed that energy-efficient washing machines do indeed increase the need to wash your clothes more, but that that increase is minimal. Which should be of no surprise to anyone