The issue with greenhouses is they tend to be humid, which is not good for miners. And during the hot summer months you need to get more heat and humidity out of the space.
This is the main problem with the heat, you need to get it out of the miner but at the same time you must be careful what air you get in also, so you will definitely need two circuits here, and then you have the distance if your greenhouse is like 50 meters from the room where you have the miners you need a lot of fans to push it, maybe dig a trench for the tubes so you don't lose that much heat but at the same time, you have to watch out if air goes above 30C not to ruin your plants, so another exhaust.
A lot of pain in the ass if you're working on small-scale stuff, might be really enjoyable as a hobby if you like this stuff but probably at one point you will get bored playing around all day with settings and temps and fan speeds depending on how sunny is outside.