Oh, that is not a hot weather friendly coop...rotten ventilation.
Not sure you could fit much a fan in there.
Do they have a run?
What roost booster product are you using?
Deep all day shade is best but....
I give a dose of
Sav-a-Chick electrolytes/vitamins about once a week during heat waves.
It
really seems to help....started this after they saved a heat stroked hen once.
Can mix up a smaller amount, just wrap the packet tight and store in a dry cool place.
Always have plain water available too.
BIG(9x14x2") chunks of ice last all day for wading, sitting, and sipping.
Much more useful to the chickens than frozen foods and treats.
Make space in your freezer!