Case Study: Another type of Sick Building Syndrome (SBS) = conCAVE towers at Duo 1. In my opinion, Shapes and Forms Feng Shui does not look favourable towards concave tower blocks. 2. On the contrary, there is no issue if the tower blocks are the usual convex design or the circular design. 3. Majority of many building towers allow excess qi or wind to flow away or distribute more smoothly away from the surface area of the tower:- 4. What about horse shoe design? 4.