4- in the summer it gets extremely hot here, up to 45 degrees c is normal >: , oh that is (113F for fellow Americans 
) ,,so no matter how much airflow is put, they will still get hot, so i have to use an AC to let the miners inhale 
some cold air or they would melt. .
) ,,so no matter how much airflow is put, they will still get hot, so i have to use an AC to let the miners inhale some cold air or they would melt. .Jeeze whereabouts are you that 45C is normal?
We get hot and humid summers in southern Ontario and as long as their was managed airflow there was no need for AC. But agree that introducing some cold air will maintain the health of the miners long term. Easy to calculate your overhead and stay profitable.