Can the large chimney be blown over by heavy storms?
This allegation has been made several times but is totally unfounded. The basic design wind speed at 10m height from the ground is 161km/h and in gusts 216km/h and 213/245 km/h respectively at a height of 450m, which values are taken from international standard tables. For most of Southern Africa, Arabia, India, Australia etc. such a GreenTower is significantly over-designed especially with its high safety factor. In hurricane areas construction will be adapted to higher wind loads. The wide-footed chimney is much less affected than high-rise television or office towers. Incidentally, the real risk does not lie in steady high wind speeds but in periodic gusts coinciding with the flue’s resonance frequencies, the most common reason of failures. The foremost experts on this, Profs. Niemann and Höffer with the world’s leading wind tunnel research facility, were also taken on board and have already established that atmospheric gust strength decreases with rising flue height and vanishes at
