Dusseldorf is a blinding place. Not so much for what it is as for where it is. Nine million people live within a radius of 50km. The giant 'Centre O' shopping centre at Oberhausen (where you will soon be able to buy a reformed Mercedes A-series over the counter) is only 20 minutes away. Just 15 minutes away are the Foster low-energy buildings in Duisburg. Half an hour brings you to the rwe tower in Essen, and in the city itself you can walk to the Rhine or Petzinka's naturally ventilated Stadt Tor.
Dusseldorf is where the post-industrial environmental action is. You can tell that by the trees, the double facades and the passive solar and natural ventilation experiments. The best one is on the Brehmstrasse, on the big roundabout and tram terminus, barely visible behind construction hoardings. There you can see the first stirring of arag 2000, the Foster/rkw competition-winning high-rise that has, after years of delay by its insurance company client, finally come on site in the form of a single wind-tunnel- tested elliptoid 135m tower that promises to win the next round in the contest to produce the world's first thermally self-sufficient, self-ventilating skyscraper.
Unlike earlier, more tentative contenders - Foster's own huge Commerzbank, Ingenhoven Overdiek Kahlen's rwe tower in nearby Essen, and Petzinka's Stadt Tor - the system developed for arag 2000 will make far more dramatic use of stack effect. Its double facades will be formed from a succession of side-by-side, six-storey chimneys, from the top of which air will exhaust at more than four metres per second. A mock-up of part of the facade on site shows the difference from earlier designs. Where the inlet and outlet vents at rwe are discreet pinpricks, the vents at arag run the full width of the spandrel panels. The difference is palpable; as naturally ventilated buildings go, this one will have the biggest 'air engine' on the block. Combined with its modest footprint, its 1000m2 floorplates, its chilled beam ceiling, its deep-plan office and its open staircase linking floors, the potential savings on operating costs could put high-rise right back at the top of the class.
But not, one supposes, here. For even though British architects and m&e people are at the heart of it, the high-speed evolution of the zero-energy high-rise is taking place in North Germany, not where it ought to be in the City of London. The powers-that-be have not even come to terms with the skin, crown and lobby school of high-rise design, let alone anticipated the impact of these automatic pistols from Germany (once they are perfected). Instead, like prisoners on a hunger strike, the masters of the City insist that research has shown their abstinence to have been correct: not only are tall buildings unwanted in the Square Mile, there is no point in them anyway.
It is reassuring that several people seem to have found this conclusion surprising. The City may not want them now, but when it is too late they will.