Famous buildings retrofit

An artists impression of how Tower Bridge in London will look once it has been retrofitted with a new low-energy LED lighting system.

Solar panels shimmer in the sunlight in front of St Peter's Basilica in the Vatican City. One thousand photovoltaic panels cover the roof of the Paul VI Audience Hall that generate enough electricity to meet all heating, lighting and cooling requirements of the 6,300 seat venue.

A project to retrofit the Empire State building in New York began in 2009. All 6,500 windows of the skyscraper are being replaced while the building's air conditioning and lighting systems are also being upgraded. It's expected to reduce energy use by over 35%.

The air conditioning system in the Sydney Opera House has been adapted to utilize sea water from the surrounding harbour.

The Eiffel Tower in Paris has reduced its energy consumption with a low energy LED lighting system. This artists impression however envisions further carbon reductions by growing 600,000 plants on the world famous structure. The company behind the project claims that 87 tons of CO2 could be removed from the Paris sky each year.