Mushroom farm - monitoring system

For safety reasons, it would be nice if you could avoid mains voltages. You could switch the 12V going to each of the fans via transistors, even use PWM if you need variable speed. Same thing with the pump, although you'll need to find one powerful enough at 12V and a more beefy transistor that the fans take. The pumps that spray water at your windscreen must be 12V - powerful enough?