We have an existing 45 Storey building consist of 2 basements, ground, two mezzanine, and 40 floors.

since the owner tendered a renovation & Maintenace work, replacing all the MEP systems, and big part of finishes, for all floors. excluding the exterior. First 3 floors will be used by owner team and facility management. Thus, owner decided remaining 40 floors to be used by tenants as offices rental. 

Which rating system is most suitable for our case?