Rolled steel I-beams used in the construction of commercial buildings have a recycle content of 45%. The design life of commercial buildings is 60100 years, though most are demolished after a shorter...

Rolled steel I-beams used in the construction of commercial buildings have a recycle content of 45%. The design life of commercial buildings is 60100 years, though most are demolished after a shorter time. On demolition today, 80% of the steel is recycled. Take the embodied energy of primary steel to be H_m
= 32 MJ/kg and that for recycled steel to be Hrc 5 9 MJ/kg.

a) What are the material life energies using the recycle fraction method and using the substitution methods (equations (7.1) and (7.2) of the text)?

(b) Report instead the material life energy using the recycle fraction method and the potential EoL credit of the steel if it were recycled at today’s recycle energy and a recovery rate of 80%.