Is smart density the way forward for Bangladesh?

[RealNapster]

yes，The tall building can solve the problem of high population density
12 floors are not enough to solve the problem

It is. If used extensively. You see, the 12 storey buildings have less initial cost, as you go up, per storey cost increases. 12 storeys is in the lower side hence cost less. Similarly they are easy to maintain, consume less energy, put less pressure on city's sewerage system, water supply system etc... The main problem is actually the 2-4 storey buildings that you see in abundance. They store much space (almost same as what a 12 storey building will take) but offer less accomodation and less value. Sleep on it.