A project involves adding a new mechanical ventilation system to an existing building. The existing air handling unit is being reused. According to the CALGreen requirements in the CMC, what is the minimum MERV rating required for the filters in this reused unit?

• MERV 8, as that is the typical minimum for existing systems.
• MERV 11, as a compromise between new and old standards.
• The MERV 13 requirement does not apply due to the exception for existing mechanical equipment.
• MERV 13, as required for all new and existing equipment.