Hello,
all proposals I read so far are not permanent.
You have to observe nature and copy her for permanent solutions.
Imagine the area around a waterfall.
The air is saturated with water. 100% air humility.
Is there mold ?
No. There is no mold.
There is moose and algae.
Why ?
Moose & algae and mold occupy the same living space.
Both grow at the same conditions.
But you NEVER get both. They are natural enemies.
Who first claim the area keep it.
I learned this from a master plant propagator. His propagation chambers where warm, moist and total mold free.
His secret was using water from a pond with plenty of moos and algae spoors.
His propagation chambers where green from all the moos and algae everywhere.
Mold is eating your plants and seeds. Moos and algae don't.
So, the best thing to prevent mold indoor is to control your air humidity.
At least measures it to know when you have to open the windows.
A power-free humidity-meter cost just $5.
Never let it got above 85%. That's the about the minimum air humidity that mold need to thrive.
I use a 2nd hand ($30) dehumidifier with a Chinese (ebay/aliexpress) air humidity controller. Zero mold.
The best thing for greenhouses and outdoor is using water with a high moos and algae spoor count (stream, pond, rain barrel - NOT tap).
Even spray this water. You will get a green, mold free greenhouse.