When we think of green buildings, we tend to think of new ones—the kind of high-tech, solar-paneled (装有太阳能板的) masterpieces that
41
the covers of architecture magazines. But the U.S. has more than 100 million existing homes, and it would be
42
wasteful to tear them all
43
and replace them with greener versions. An enormous amount of energy and resources went into the
44
of those dwellings. And it would
45
65 years for the reduced carbon emissions from a new energy-efficient home to make up
46
the resources lost by destroying an old one. So in the broadest
47
, the greenest home is the one that has already been
48
. But at the same time, nearly half of U.S. carbon emissions come from heating, cooling and
49
our homes, offices and other buildings. "You can"t deal with climate change
50
dealing with existing buildings," says Richard Moe, the president of the National Trust.
With some
51
, the oldest homes tend to be the least energy-efficient. Houses built before 1939 use about 50% more energy per square foot than
52
built after 2000, mainly
53
the tiny cracks and gaps that expand
54
time and let in more outside air.
55
, there are a tremendous number of relatively simple changes that can green older homes,
56
historic ones like Lincoln"s Cottage to your own postwar house. And efficiency
57
can save more than just the earth; they can help
58
house owners from rising power costs.
59
, a nationwide effort to improve existing buildings could
60
hundreds of thousands of green jobs.