If there were no vents, and the windows still got moisture build up, then that would confirm (IMO)that the moisture was getting in the window cavity through the walls, brick etc. Thus totally eliminating the vents as the problem.
This can be done temporally by taping the inside vents closed
There is only one window on the church that was vented to the inside, it is the one I discussed earlier as my test case. All other windows are vented to the outside. This would make it difficult to tape off the vents as the tower is quite high. Not impossible though.
As I mentioned earlier, the windows are totally painted and sealed. The tower windows are the only exception as the storm glazing frames are surface mounted to the brick. The wood is totally sealed, but there is the potential of moisture migrating through the outer course of brick.
I appreciate all the comments, but I am going to wait until the humidity is addressed first. No church should be in the humidity levels up to eighty percent as it would affect so many different architectural elements. Once the humidity is brought to moderate levels, I will see the condition of the windows at that point. It is my assumption that it will clear up.
A quick point. "Relative Humidity" (RH) is a measure of moisture in the air relative to the ambient temperature. It varies infinitely with the temperature the air.
The real measure of moisture is Dew Point which is the temperature at which condensation occurs.
First, let me forward a fun little calculator for relative humidity and dew point and temperature: http://www.dpcalc.org/
Trying to put an end to the confusion of relative humidity and dew point, I went back to my engineer friend. He put it this way: Relative humidity is like two glasses of water. One small glass (representing cold air) and one large glass (representing warm air) are both half full (fifty percent relative humidity). The image is pretty self explanatory.
Dew point is the point where everything is going to go wrong. In our case this would be the envelope of the building. Taking out the water from the larger glass (warmer air inside) will greatly reduce the amount of condensation at the dew point (the envelope of the building). Lowering the relative humidity in the building at the warmer temperature greatly lowers the amount of water (large glass) that is available to accumulate on the windows. This way if condensation is going to happen at the dew point, there will be less water available resulting in less fogging or icing. This allows the vents to be more effective.
Hope this helps.
Last edited on Fri Jun 13th, 2014 02:39 pm by jjkrol
Lowering the relative humidity by necessity means lowering the dew point, and it's a good idea. The only problem with relative humidity is that it's "relative". Dew point is a measure of the mass of water in a given volume of air. When the dew point is reached all of the water in the air will condense on the coldest surface. There is no difference between slightly damp and soaking wet.
The bottom line is to reduce moisture (relative or dew point) as much as possible, and when venting, to install vents that are of sufficient size to allow good air circulation and drying of any condensation that may occur.
If you play with the calculator on the link I added to the previous post, you will find that at seventy degrees the relative humidity and the dew point are virtually the same within fifteen degrees up or down. Assuming that the calculator is right, I find it a lot easier to carry one easy instrument to obtain humidity when dealing with the interior space. I do not say that dew point is worthless and definitely has its place, but for quick reference, I'll go for easy.
Last edited on Fri Jun 13th, 2014 11:57 pm by jjkrol