stone and dirt
I love to create things in a way they can be easily uncreated. Most items we buy today, a house, a car, become a burden when they no longer have a purpose. The processes involved to uncreate those objects is huge.
This stone floor on the other hand does not use cement or glue. The big and heavy slabs of stone lay fixed on sandy earth. They can be removed with ease, the moment they no longer serve. There will be no need for force and tools to release them from their current formation. Nor is there need for the tools and the maintenance of those tools. The stones can be lifted by hand and will not be damaged in this process. They will remain as they where, valuable, and can be reused again. The total energy used to create and uncreate this floor is far less this way.
Eventually everything returns, everything goes. Therefore look at the things you create in this world. What energy does it cost to create and how much energy will it cost once it serves no more.