The most economical and eco friendly construction is earthen material, such as concrete blocks, bricks, stones etc.
Depends on how its done. Its not actually that good though. It takes too many trees so its not sustainable. Its not eco or human friendly since they apply formaldehyde to keep the wood from rotting. The disadvantages are many. Bamboo is a better option, it grows faster than trees and trees can be saved by using bamboo instead. The advantages of bamboo are far more than wood.
Niraj is right. Wood is sustainable, given a small enough population. On the other hand, it is not suitable for the supporting framework of tall buildings, the most environmentally-friendly way of housing the population. So, it depends on the use to which you want to put it.
Constructing with wood is sustainable. But i think using iron or steel is a better option. Because if you use iron or steel you don't have to cut trees. If you use wood you have to cut trees which is unfriendly to environment. If you cut trees you have to wait a long time to recover the damage or you won't able to recover it.
It's good for there are both sides, handle with care. http://www.pass2win.info/
Is it sustainable or not? IS it eco friendly or not? Can the advantages over come the disadvantages?