Sustainability and policy - Climate Change: Biological and Human Aspects - page 466

William Stanley Jevons in his 1865 topic The Coal Question . The classic example
is space heating. Over the years improved household insulation has reduced the loss
of warmth from homes. However, the trend has not been one of reducing the energy
that nations use for domestic space heating. Leaving aside the question of reduced
household occupancy (Figure 7.3), home owners have tended to recoup the energy
savings by being able to have warmer homes. This maintaining of dwellings at higher
temperatures offsets potential savings. Similarly, whereas there has been an overall
trend in improved fuel efficiency of cars (in terms of fuel consumption/unit of car
mass per kilometre travelled) so this has been more than offset by the distance trav-
elled per year by car owners. (This is one reason why the green lobby is against
construction of new motorways as it leads to increased car use, hence the need to
build even more motorways; Tyme, 1978).
Second, we might devote our increased affluence (see the previous chapter) to using
energy in less efficient ways. An example might be the use of less-efficient (in terms
of common occupancy energy per passenger kilometre), larger sports utility vehicles
(or SUVs) than traditional smaller and lighter family cars. This trend was manifest
in developed nations early in the 21st century where some SUVs began to be used
solely in urban settings and not off-road, for which they were notionally designed.
The motivation here is largely psychological in that SUVs are sometimes perceived
as conferring status for the driver/owner.
These two trends of improved efficiency and increased consumption serve to offset
each other. Indeed, in some cases they can cancel each other out. Here an example
would be the energy used in watching television in the UK. In the 1950s televisions
were still a luxury and very rare but the number of households in developed or
industrialised nations with television sets was increasing. For example, in the UK
in 1955 television sets consumed about 830 GWh. By 1970 more households had
television sets and the energy consumed that year was around 5000 GWh. However,
during that decade semiconductor technology was being introduced to replace the old
thermo-electronic valves and so the electricity consumption per set began to decline.
In the late 1970s colour televisions began to replace the former black-and-white
models (see Figure 8.1b) and energy consumption per set rose once more. However,
by 1984, despite almost universal use in the UK, these sets too had become more
efficient and so annual consumption decreased almost to the 1970 level (Evans and
Herring, 1989). The 1990s saw an increase in the number of television sets in the
UK and with the advent of video (and later still DVD) increased total UK energy
consumption not just through viewing but also by the sets themselves being left on
standby rather than being turned off (in addition to, of course, the ancillary video and
DVD equipment). Domestic equipment left on standby accounts for approximately
10% of total domestic electricity consumption in the UK today. Finally, the new
generation of high-definition, wide-screen plasma sets consume almost five times as
much electricity as the sets they are replacing.
This pattern of counteracting trends - of improved efficiency on one hand and
higher-use, additional new energy-consuming technology on the other - is common
to virtually all areas of energy use, although on balance one tends to dominate over
the other so that they rarely negate each other exactly. For these reasons, since the
1970s to the early 2000s electricity consumption by UK domestic appliances and