As far as I understand, those fans with radiator can at *most* cool to room temperature. I have not seen them with a Peltier stage, and even if then wonder whether it is too weak anyway.
I have to go *below* room temperature, i.e., while room temperature is at >90F, terrarium is at <80F. So an active cool down is required.
I have the waterfall running, so this is not theoretical, but actually implemented.
Hi Piotr. You didn't tell us what kind of orchids you want to grow. One simple possibility is to grow in the underground basement under artificial light, eventually LEDs.
Another way is using cooling pads. The evaporation cools down the air and enhances humidity. These systems are used in farms for raising pigs and to protect them from heat stress.
My suggestion is a hot water heat pump for indoor positioning. You use the electric energy for hot water and/or heating and get the cold exhaust air for free.