I am aware of how to use vent holes. The idea is to make my design more efficient then the others. The design that your showing is like all of the others out there. There has to be something that i can do to add to the other designs.
You obviously didn't look well enough at my design.
As the cool air enters the incubator it will be mixed with inside air and addionally heated when passing the heater located on the downstream side of the fan.
Also, you can't close the incubator for some time (just to save 2W of energy). Fresh air must be added at all times. Using a sliding door to allow only the minimum fresh air to enter will keep heating expenses to a minimum as well.
No chicken will hatch from a rotten egg. Since air exchange is a constant factor regardless of temperature (the box size won't vary) you can easily find out the optimum setting of the sliding door.
Connect a plastic pipe/hose to the vent air port and inhale the air. If you get dizzy you know the air is of no good quality and probably push the slider open for one more hole until you can breathe the air out of the incubator freely.
Chicken generally breathe the same air as humans. So don't worry.
If you can afford purchasing a CO2-sensor and the appropriate controller, why not make it scientifically sophisticated?
I bet the chicken hatched will say "beep - beep"; neither will they say "quack quack" nor "Thank you for the fresh air".
On the other hand, why would one waste energy using an extra air pump having that energy saved for a super-efficient heating system?
Boncuk