Post History

Calculating Max humidity for a house

I want to write some code to control my whole house humidifier. I want my code to calculate the percentile relative humidity above which dew will form on my windows.

I have sensors for air temperature and humidity inside and out, and pressure, which better be the same because I don't live in an airplane.

I'm trying to brush up on my math so I can understand the clausius-clapeyron equation.  I think I understand that there's a basic algebra cheater formula but that it doesn't work outside of common humidity ranges and I want my code to be solid.

I also suspect I might need to add a temperature sensor to the internal surface of the windows.  But I'm hoping that there might also be a formula to calculate with that temperature will be given the indoor and outdoor and the r value of the window.

I'm hoping they can look something like this below. Disclaimer: I do not expect in any way these examples below work

InnerSurfaceTemp=TempIn-((TempIn-TempOut)/RVal)
MoldRH=Rh where dewpoint=indoor temp
MaxRh= MoldRH-2.  ( For a safety threshold)

What formula can I use to determine the inner surface temp of a window?

And what formula can I use to determine the maximum indoor RH to prevent condensation on that window surface?

I think this is a physics problem but please forgive me if I am barking up the wrong tree.