1. CODE REQUIREMENTS:   The International Mechanical Code requires that make-up air is heated and/or cooled within 10 degrees of normal space temperature.
2. KITCHEN COMFORT:  Without tempered make-up air whatever it is outside is what you bring back inside  (110 summer day — 110 make-up air; -5 winter day — -5 make-up air.)
3. ENERGY SAVINGS:  Without tempered make-up air more of a load is required from the other HVAC systems in your space.  (Example: Running AC in the entire restaurant to keep kitchen comfortable during prep and clean-up time.)

Please remember to check with your local jurisdiction for specific requirements.