Recyclability will be a key factor in the selection of materials, in addition to carbon footprint.  

This approach is particularly evident in the choice of interior partitions for the stadium, which must be made of heavy materials. These will not be constructed from concrete blocks, but from CO2-negative Carbstone blocks. The amount of CO2 absorbed during the production of Carbstone blocks is, in fact, greater than the amount emitted. Furthermore, these blocks continue to extract CO2 from the air even after they are manufactured, and retain it permanently. Carbstone building blocks are also 100% recyclable: when the blocks are crushed after a building is demolished, only sand and gravel remain.