I’m not that familiar with hot temperatures but intuitively I would think that a difference of 2-3 degrees (Celsius) when temperatures are already high at around 40-45 to be noticeable.
For example if you go from 40°C to 37-38 that’s a quite good improvement if you don’t have to spend energy for this. I don’t know if that also applies to more extreme temperatures like 47°C, I cannot really imagine how that feels like.
From what I understood 2-3°C is not a safe goal but something you can get from the passive cooling solution the initial commenter mentioned. I would guess you can add extra active measures on top?
For example if you go from 40°C to 37-38 that’s a quite good improvement if you don’t have to spend energy for this. I don’t know if that also applies to more extreme temperatures like 47°C, I cannot really imagine how that feels like.