This was a Concrete iron structure, and usually structure like this will burn very slow and itll take time for the fire to go from one for the other. But this fire 20 floors in less than half an hour. You might consider that the building was just upgraded to be green, environmentally clean. It has been suggested that insulation is put on the outside of the building and a new green low-energy heating system was put in the building. It will be interesting to find out if this insulation on the outside is flammable. This would not be unusual for the global warming crowd to sacrifice safety to save a gallon of diesel fuel.Just a guess that they were going to find out that the upgrade of this building cut many corners when it comes to safety of the occupants, to accomplish lower energy use and save the planet.