just wondering how you regulate the humidity in the greenhouse

i assume in the day humidity should rise even if you air it out in the morning and at night

Without elecky in there I think its just down to plenty of venting. You get louvre (sp?) vents on most greenhouses at the bottom, and opening windows in the roof, this should circulate the air pretty contantly and keep humidity a bit lower than things can get in say - a polytunnel - with only doors at each end, i think the humidity would go a bit through the roof in one of these.

Ofcourse with elecky, you can use all the equiptment you can indoors, like humidifyers, dehumidifyers, foggers, etc

I've got two ceiling windows, a side window (waist height) and I leave the door open - which faces into the prevailing wind.

Has worked for four years now, but, had some fungus this year (from tomatoe plants I think, and our very wet summer) - so next year I'm going to add an extra window to the far end of the greenhouse to encourage more through air.