When we think of green builings,we tend to think of new ones—the kind of high-tech,solar-paneled masterpieces that make the covers of architecture magazines.But the U.S. has more than 100 million existing homes,and it would be ____wasteful to tear them all down and _____ them with greener versions.An enormous amount of energy and resources went into the construction of those houses.And it would take an average of 65 years for the_______carbon emissions from a new energy-efficent home to make up for the resources lost by destroying an old one.So in the broadest_ ______the greenest home is the  one that has already been built.But at the same time,nearly half of U.S. carbon emissions come from heating,cooling and _____our homes,offices and other buildings."You can't deal with climate change without dealing with existing buildings",says Richard Moe,the president of the National Trust.

  With some ____,the oldest homes tend to be the least energy-efficent.Houses build before 1939 use about 50% more energy per square foot than those build after 2000,mainly due to the tiny cracks and gaps that ____over time and let in more outside air.

  Fortunately,there are a ____number of relatively simple changes that can green older homes,from______ones like Lincoln's Cottage to your own postwar home.And efficiency upgrades can save more than just the earth;they can help___property owners from rising power costs.

 

A.accommodations                     B.clumsy                              C.doubtfully                               D.exceptions

E.expand                                   F.historic                              G.incredibly                                H.powering

I.protect                                    J.reduced                              K.replace                                    L.sense

M.shifted                                   N.supplying                          O.vast    

 

 

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