Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
When you change the amount of outdoor air, the mixed air temperature entering the coils also changes (at least up to 100% outdoor air). I don't see exhaust fans in your simulation so any exhaust air is removed at the outdoor air mixing box and a mixture of outdoor air and return air determines the mixed air temperature. As the mixed air temperature changes the coil performance changes. The incremental changes from 1 to 2, or 2 to 3 are not all that different. Nor are the changes from 5 to 10, 10 to 15 and 15 to 20.
Check the mixed air temperature for these simulations to see how it is affected by increasing outdoor air quantity. Also, have you checked the zone temperatures to make sure they are the same between these simulations?
