The Mairie in Paris has announced that the Christmas and New Year decorations on the Champs-Elysées will be lit by low-energy bulbs. The 415 trees will be lit along the 2.5 kilometres of the avenue from 26 November until 20 January by a million fluorescent rather than incandescent bulbs. This is apparently 8 times more than usual which to my mind goes some way to defeating the object.
The Eiffel Tower lights were changed during 2004/2005. From the Tower's website, this has resulted in a 30% saving in electricity. The lighting accounts for 6% of the total energy bill. There is an interesting New York Times' article about the Eiffel Tower lighting over the years.