We have a family run aquatic shop. Due to the high humidity from the fish tanks the front glass of the shop streams with water at night when all doors are closed.
There is a small ventilation vent along the top of the windows but make no effect.
We could install a warm air curtain at the base of the glass which I am sure would solve the problem but the installation and running cost would be considerable. Alternatively we could add mechanical vent but again the costs would be high.
We had thought to install secondary double glazing (there is only single glass there at the moment) with possibly trace heating at the bottom of the glass between the single and double glazed units when it is really cold but are not sure if this would work adequately.
The tanks are maintained around 22 deg. C and there is no other heating ( we did put a low wattage tube heater at the bottom of the glass which had a minor effect but needed to be much higher wattage and thus expensive).
During the day the door is left open so there is little problem. I have not taken a night time wet/dry bulb temperature reading but have assuned it would be around 18 deg. C at high humidity.