Kitchen Exhaust Make-Up Air

Yes you can use the makeup air as outdoor air supplied to the kitchen, but you'll need to use an appropriate ventilation efficiency (Ez) number for "zone air distribution effectiveness". Air introduced directly into a bypass hood would not count. In the exhaust only case, Ez is 0.8 for a louver on the opposite side of the room from the exhaust air inlet or 0.5 for a louver near the exhaust air inlet. If you have overhead diffusers distributing makeup air from a supply fan, you will need to make a judgement on what number to use for Ez. You can find Table 6-B with appropriate Ez values in the ASHRAE 62.1 Users Manual, which should be available as a Credit Resource IEQp1 through LEED Online on the right side of the IEQp1 credit information screen. If you supply air that is never more than 15 degrees above room temperature through ceiling diffusers that are well away from the exhaust hood, you should be able to use 1.0 for Ez. For warm air in the same configuration, Ez=0.8. If the supply air is distributed only immediately next to the exhaust hood, I would use an Ez of 0.5.