Windows
not only let light in to cut down an electricity use for lighting, but the light
coming through the window also provides heat. However, windows are not something
people typically associate with being a cutting edge technology. Researchers are
now working on new technologies that enable a window to quickly change from
clear to dark and anywhere in between with a flip of a switch.
"It took us a long time to figure out what a window really is," says Claes
Granqvist. He's a professor of solid-state physics at Uppsala University in
Sweden. "It's contact with the outside world. You have to have visual contact
with the surrounding world to feel well." So, windows and natural light are
important for improving the way people feel when they're stuck
indoors. Yet, windows are the weak link in a building when it
comes to energy and temperature control. In winter, cold air leaks in. When it's
hot and sunny, sunlight streams in. All of this sunlight carries lots of heat
and energy. And all of this extra heat forces people to turn on their air
conditioners. Producing blasts of cold air, which can feel so refreshing,
actually suck up enormous amounts of electricity in buildings around the
world. Windows have been a major focus of energy research for a
long time. Over the years, scientists have come up with a variety of strategies
for coating, glazing, and layering windows to make them more energy efficient.
Smart windows go a step further. They use chromogenic technologies which involve
changes of color. Electrochromic windows use electricity to
change color. For example, a sheet of glass coated with thin layers of chemical
compound such as tungsten oxide works a bit like a battery. Tungsten oxide is
clear when an electric charge is applied and dark when the charge is removed,
that is, when the amount of voltage is decreased, the window darkens until it's
completely dark after all electricity is taken away. So applying a voltage
determines whether the window looks clear or dark. One
important feature that makes a smart window so smart is that it has a sort of
"memory". All it takes is a small jolt of voltage to turn the window from one
state to the other. Then, it stays that way. Transitions take anywhere from 10
seconds to a few minutes, depending on the size of the window. The development
of smart windows could mean that massive air conditioning systems may no longer
need. "In the future," Granqvist says, "our buildings may look
different."
单选题
Which of the following statements does not indicate the importance of
windows as described in the first two paragraphs?
A. Windows can change from clear to dark to save energy.
B. Windows help to save energy by letting light in.
C. Windows help to save energy by providing heat.
D. Windows enable people to have contact with the outside world.