Those windows look like the windows in our barn - built in 1841. Our windows are not double hung or casement. If we want then out for air flow, we have to take them all the way out of the casement, put them away for the summer and replace with screens.

Have you asked your local window suppliers?

Spend money. Red from the factory is expensive.

Lets see the barn pictures. Most manufacturers have a "standard'ish" red available. Not sure it will be that bright though.

Looks almost like it’s wood with thick coats of paint on it to make it look old. Would a red window give you this look?

Yes if it is the correct wood window.

Sand Creek Post and Beam. Talk to Len or Jule.

Thank you @starcraft