ÜDS-Fen 2003-2 Soru=52

We learn from the passage that the new-style roof ----.

The Michigan factory of a leading car manufacturing
company already has its place in industrial history. It
is famous primarily on account of record-breaking
models produced there between 1927 and 1931.
Now the refitted factory is back in the limelight as one
of the world's most architecturally advanced
buildings. The height of new technology will be its
42,000 square meter roof. Dubbed a "living roof by
the company, it consists of a ground-hugging plant
called sedum which is growing in a 7.6 cm-thick matlike
material. The sedum insulates the roof, reducing
heating bills by as much as five per cent and saving
on replacement costs. It lasts twice as long as a
standard roof because it doesn't shrink or expand
when the temperature varies. It is also expected to
become a habitat for butterflies and birds. Embedded
in the roof are 36 skylights that let in natural light. On
sunny days the factory will operate with up to half of
its lights switched off. The company also intends to
clear the soil around the factory to remove the
chemical by-products of years of steel
manufacturing. The car company will plant native
bushes, flowers and trees that will break down
polyaromatic hydrocarbons.