Not many people will think of urban planning / infrastructure planning when they think of 'going green'. However, the places where people live, work and do their things, decide for a large part how much energy someone produces. This is mainly through transportation but also through living in a energy-efficient building.
I will give Hong Kong as an example.
Especially the US but also Europe can learn from this. Not that we suddenly all need to live in a small apartment in a crowded city, standing in the metro like sardines in a can, but urban planning should focus on building more dense, especially near hubs of transport like train stations. This is called Transport Oriented Development in planning science. So less 'urban sprawl' (suburban areas with widespread free standing houses, open areas) and more dense and mixed used development.
This cycle must be broken and it can only be broken by intervention of the government: