How difficult is it to regulate a GH?

[Ray]

I have my greenhouse automated like this:

HEAT: Propane heater on a thermostat; maintains a minimum temperature.

VENTILATION: 24/7 circulation fans inside.
Two shutters in front wall that open on the gas-cylinder openers automatically. When interior temp reaches 80°F, a large exhaust fan kicks on, pulling LOTS of air through the GH.

HUMIDIFICATION: Jay-Bird Aquafog 700 on a humidistat.

I had swamp cooler when I lived in Louisville KY, so I know for a fact that it can be effective, even in relatively high humidity. I am playing with the idea of a vertical one using stacks of EcoWeb as the dispersing medium.