Was that in an urban area Kalmsg? I think they need clear air to be effective. There are a couple of vertical axis wind turbines on the new ANZ building at Docklands in Melbourne, but I have no idea how effective they are, and this link does not specify either:
I visited the CH2 building in Melbourne a few years back (was a 6 star energy rating at the time) and found that the new Melbourne City architect there was an old friend of mine. He informed me that the wind turbines on the top of that building were poorly designed and did not contribute much (anything?) in the way of power so now they are more for show rather than anything else. CBD areas are not particularly good for wind energy because of the turbulence and lack of clear air. My brother has solar panels and a miniature wind turbine on his catamaran - there's plenty of clear air off the coast of WA!
