1

Rebound Effect


In this lecture I want to talk about the rebound
effect, a phenomenon in which while we have increased efficiency in a process or a technology,
there is still a net gain in the energy used. We’ll quickly define efficiency as “the ratio
of the useful work performed by a machine or a process to the total energy expended.”
The rebound effect is easily seen through examples. Many cars have increased fuel efficiency
now, but knowing that we tend to change our behaviors so we design and build bigger and
faster cars, there are more cars on the road, and we drive them more so any of the gains
that would have come from efficiency are essentially wiped out by these behaviors. Printing and
paper is another good example. Back in the 1980s when offices were just starting to get
computers people said oh, we’re going to have paperless offices, we can look at everything
on our screens, but what actually happened was that it was so efficient and cheap and
easy to print things out that that’s what people did and now there is much more paper
used in offices than in pre-computer days back in the 1970s and before. Green policies
can have unintended effects, rebound effects. In the Netherlands people bought hybrid cars
thinking that they would do something good for the environment, but for convenience they
actually ended up driving them often in the gas mode and so they ended up spending more
energy on the car than they would have with a conventional car. This was also reinforced
by the fact that the Dutch government gave huge rebates so that motivated people to buy
the cars, and they were so cheap that people didn’t pay as much attention as they should
have to the efficiency of what they were actually doing. Technology begets technology as additives.
We have computers, we have music players, we have tablets, we have Smartphones, we have
game consoles, we have Smart watches, we have other wearables, and as we add these technologies
we don’t get rid of the old ones. We keep them around so even though each individual
technology might be more efficient than it was in the past, we continue to add new technologies
to our repertoire. This is consistent with our capitalist economic system in which corporations
have to grow at about 3% a year, and this is quite an aggressive target of growth. It’s
hard to keep that up so companies have to always be trying to sell us more goods and
services or they will go out of business or their shareholders will not be happy. So,
this kind of dynamic is built into our system. The rebound effect has a lot of impacts. It
affects energy use, materials consumption and electronic waste. As you probably know,
we have a huge and growing problem with e-waste. There are a lot of toxic chemicals that go
into the manufacturing of information technology. We really don’t have a good way of dealing
with this, and this is something that we are trying to work on. It’s important to do a
sociotechnical analysis of the rebound effect and not to just look at each individual technology
in isolation. What we want to do is measure the input and the output of the entire system
including people’s actual behaviors with the technologies, and certainly not just look
at the efficiency of an isolated technology by itself. To do this kind of analysis we
start with the math. Efficiency is a ratio so there is only so much it can tell us. To
control resource use we have to define absolute acceptable levels of whatever quantity we
are interested in. For example, we have to place a limit on C02 emission if we are actually
going to end up in the end with a reduction in emissions. Lorenz Hilty is a Professor
of Informatics and Sustainability at a university in Germany, and he has studied the rebound
effect extensively. He says, “As developments up to now have clearly shown, there is a risk
that more efficient technology may induce more material and energy throughput through
the economic system than it saves.” He recommends that we “accept more virtual, immaterialized
goods and services” to offset the rebound effect. I think this is a really interesting
direction for future research. Here are a few articles. There is a lot on the Internet
if you want to read more about the rebound effect. There is one by Hilty, and all of
these are available and highly recommended. Thank you.

Glenn Chapman

One Comment

Leave a Reply

Your email address will not be published. Required fields are marked *