404.3 Zone Ventilation Efficiency. The zone ventilation

efficiency ( Evz ) shall be the efficiency with which a system distributes outdoor air from the intake to an individual breathing zone, and shall be determined in accordance with Section 404.3.1 or Section 404.3.2. [ASHRAE 62.1:A1.2]

(2) Approved automatic carbon monoxide sensing

devices shall be permitted to be employed to modulate the ventilation system to not exceed a maximum average concentration of carbon monoxide of 50 parts per million during an eight-hour period, with a concentration of not more than 200 parts per million for a period not exceeding one hour. Automatic carbon monoxide sensing devices installed to modulated parking garage ventilation systems shall be approved in accordance with Section 301.2. 403.7.2.1 Alternative Exhaust Ventilation for Enclosed Parking Garages. 403.7.2.2 Minimum Exhaust Rate. [HCD 1 &2] In lieu of the exhaust rates in Table 403.7, venti- lation systems shall be capable of providing 14,000 cfm (6608 L/s) of exhaust air for each operating vehicle. Number of operating vehicles shall be deter- mined based on 2.5 percent of all parking spaces (and not less than one vehicle). 403.7.2.3 Exhaust Inlet Distribution. [HCD 1& 2] To ensure proper exhaust of contaminated air and fumes from parking garages, exhaust systems utilizing multiple exhaust inlets shall be designed so that exhaust inlets are distributed in such a manner that no portion of the parking garage is more than 50 feet (15 240 mm) from an exhaust inlet. Such exhaust inlets shall be installed so that the highest elevation of the exhaust inlet is no greater than 12 inches (305 mm) below the lowest ceiling level. Exception: Garage exhaust systems designed with- out distributed exhaust inlets may have their exhaust inlets designed based on the principles of engineering and mechanics and shall provide the minimum required exhaust rate in Table 403.7. 403.7.2.4 Exhaust System Operation. [HCD 1& 2] Exhaust systems shall operate continuously unless one of the exceptions to continuous operation of Section 403.7.2 is utilized.