I am sitting in my "TV" room which is 10 x 11 ...
due to my geese starting to lay eggs inthe snow last spring, I brught my very old sportsman and 4 styrofoam incubators in here..It was to cold in the garage for incubators.. I hatched out about 400 eggs before It got warm enough outside to move the bators.
I never had an odor problem.. My bride would have let me know is a minute if there would have been..
If your hubbies friend could smell his bator, in a barn, he must have had some really ripe eggs in there..LOL
the hatched shells will give off an odor before they dry up..but not bad...
..jiminwisc.........