Which is the "greenest" University in Birmingham?

Many Universities around the city of Birmingham are starting to do more for the environment. From more recycling facilies, to the “eco power rangers” groups, to to farmers markets, conservation societies and even piloting the all-new electric cars scheme, it seems they all boast green credentials.
But I want to know which University – out of Birmingham City University, University of Birmingham, Aston and University College Birmingham – is the most environmentally aware?