Wich companies use arduino for real automatic home projects?
None (to my knowledge).
I need a web site in wich I can find real domotic home using Arduino.
What does "domotic" mean?
Which is the durability of arduno shields.
That depends on the shield and for most of them it's not specified anyway.
Wich is the durability of sensors.
1 second to 100 years.
Are the sensors reliable in mensuration or they are only for amateurs?
Most sensors for amateurs are very reliable and often the same as used in professional equipment. Does your home automation system has to fulfill the army requirements? Specify what's reliable enough for your needs! Usually the "amateur" stuff is more then reliable enough for home automation purposes but again, that depends on what kind of device you need and what special requirements you may have.