Environmental Engineering Reference
In-Depth Information
W/m
2
of floor area in China, about 14 W/m
2
in Japan,
15-20 W/m
2
for all types of U.S. housing (mean of@17
W/m
2
for single-family detached houses), and 25 W/m
2
in Canada (EIA 2001a; Natural Resources Canada 2000;
Zhang 2004).
These power densities reflect more than just differ-
ences in climate. Japan averages annually 1,800 degree-
days, the United States about 2,600, and Winnipeg
5,900. But my superinsulated house in Winnipeg con-
sumes annually just 35-40 W/m
2
of its foundations, a
rate nearly identical to a typical two-story detached U.S.
house in a climate with less than 50% of Winnipeg's heat-
ing degree-days. In addition, different lifestyles and afflu-
ence levels set different consumption baselines. The
Japanese and British tolerate much lower indoor temper-
atures (below 15
C) than North Americans and Cana-
dians (typically above 18
C) and commonly heat only
some rooms in a house or, in the Japanese case, merely
parts of some rooms (traditionally with charcoal-burning
kotatsu, now with electric heaters). Traditionally there
has been no winter heating in China's provinces south
of the Yangtze despite the fact that the room tempera-
tures repeatedly dip below a comfortable level. Canadians
and Swedes heat on average 2.5-3 times more water
than do most Europeans or Japanese. And in low-income
countries electricity use is dominated by meager lighting,
whereas in affluent countries appliances consume the
most.
Commercial buildings have a higher specific energy use
than households. Most multistoried glass structures put
up in North America between the early 1950s and the
early 1970s averaged 110-140 W/m
2
of floor area. A
typical 20-story glass building of those years required 2-
2.5 kW/m
2
of its foundation, and New York's 110-story
World Trade Center twin towers used about 12 kW/m
2
of their foundations, or a total of 80 MW per building.
By the mid-1980s the primary energy required by new
office buildings was below 50 W/m
2
, and many all-
electric buildings have been designed for 10 W/m
2
or
below, less than 30 W of primary energy per square me-
ter of occupied area (or, for a 50-story structure, no
more than 1.5 kW/m
2
of the foundations). An extensive
survey of U.S. commercial buildings shows a nationwide
mean of about 33 W/m
2
for all structures, with the rates
ranging from less than 15 W/m
2
for storage to more
than 90 W/m
2
for food service and health care buildings
(EIA 2005a). On average one-third of this flux went for
heating, one-fifth for lighting, and only about 6% for
office equipment.
The rising share of energy use for transportation is
a universal marker of economic development. In 2000
that sector claimed nearly 30% of U.S. TPES, 25% in Ja-
pan, but less than 10% in China. Waterborne transport
powered by diesels and gas turbines is relatively efficient
and incontestably the cheapest way to move goods or
people. Pipelines are best for the bulk movement of
liquids and gases, but trains, powered by diesels or elec-
tric locomotives, are the best general freight performers
on land (Smil 2006). Electric motors also power all
high-speed passenger trains, most notably Japan's shin-
kansen and the French TGV, train
`
grand vitesse (fig.
9.9). In road transport diesels are the preferred prime
movers for trucks and buses, and they now also account
for nearly half of new European passenger cars; elsewhere
gasoline-powered vehicles dominate. In 2005 about 25%
of global refinery output was motor gasoline, 33% middle
distillates, and about 6% aviation kerosene.
Gasoline and diesel fuel consumed by vehicles on busy
U.S. urban interstate highways (up to 14,000 vehicles a
day per lane, lane width 3.6 m) translates to power den-
