Unfortunately, that is a "chicken or egg" question. If we construct our dwellings out of biodegradable materials, then our dwellings have a limited "shelf life" before we are forced to build another; yet, if we construct our dwellings out of cement and bricks, they will last longer. Ultimately, they will be torn down in the name of progress, and potentially used as viable fill material, depending on the application. Being eco-conscious is one thing; being eco-friendly is an expensive thing. Imagine as well the impact to our lives, if we had to anticipate regular "new house" purchases, like we do with our cars? Imagine the economic implications to our society. We would live differently.