Atree?

Imagine a project that does not need to be constructed, because – being a tree – it grows by itself. Such a project only needs to be planted. Therefore the transportation of the materials for such a project is very energy efficient, because as a matter of fact, no major transportation of materials is actually necessary. The only materials to be transported are the seeds for planting. And the only energy spent is to prevent hastiness and impetuousness as such a project needs a lot of time and patience to grow.