Im in the process of opening a bar/tavern in Oregon. Im doing a ventless/hoodless. Building inspector has told me that even if I get rid of cooking equipment and have just my low-temp undercounter dishwasher (which aren't suppose to require it as they don't produce more steam than hot water out of faucet) I will be required to put in a minimum 50 CFM fan. I want to know what the lowest amount of CFM's of exhaust you can have before make up air is required. The math from mechanical code stated .70 CFM per square foot and my kitchen is 100 square feet approximately. My original plan was to have the undercounter dishwasher and 2 pieced of ventless equipment, which are also not suppose to require heat exhaust as they have them built into the equipment, and the math had something about 100 CFM per piece of equipment. I need someone to tell me what the lowest allowable amount of CFMs is before make up air is required to be installed. If its less than 400 I need an engineer to do the math and provide a stamp so that I can submit that to the building inspector and satisfy his need for it. I want to put in a fan that is the lowest allowable amount to help allow me to put the most pieces of equipment I can which sounds like it may only be 2 or 3. Exhaust duct will have one to two elbows and only need to exhaust about 10-15 feet out the side wall of building. I don't know much about this stuff and any help that can get me going is appreciated.