Shots Fired... (Condensation Guns).

We can do this by measuring the temperature of the surface in question (lets say a window reveal for example), and then comparing this to the dew point temperature - this being the temperature at which water vapour condenses back into a liquid, or in other words the temperature at which condensation occurs.

If a surface temp is very close to dew point temperature, then obviously that surface won't have to get much colder for condensation to occur.

However to work this out, we would need the following:

-An air thermometer

-Surface thermometer

-Hygrometer to measure relative humidity

-Psychometric chart to work out dew point

There are devices which can do all of this for us - condensation guns.

Exactly as above, they work out dew point and measure the temperature of whatever we point them at, comparing the two to visibly indicate condensation risk.

I'm not stating that these are the most accurate devices in the world (there is some variation between the two models which I have), and I would always allow any hygrometer time to acclimatise before taking a reading, but it's a handy tool which is easy to use nonetheless.

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PS: They're also inexpensive