The percentage of Realtive Humidity (RH) contained in a building will determine if condensation is able to form. When condensation is allowed to occur it will first form on the coldest surface of any building, which is generally the glazed elements. When new buildings are drying out there is an extremely high level of RH due to the thousands of gallons of water used in the construction processes. Please read on below for a guide to condensation. It's more complex than you thought!
Condensation will occur on any surface with a temperature less than the dewpoint of the atmosphere near the surface. Therefore, when the surface temperature of any part of the patent glazing and the relative humidity of the atmosphere reach a critical combination, condensation will occur.
Ground frost, cold rain and low temperature with high wind will exacerbate the formation of condensation. Adequate ventilation will serve to reduce condensation. Inside buildings, the humidity will be increased by the release of moisture from cooking of food, the presence of people or a large body of water, such as a swimming pool.
This moisture can reach high levels where ventilation is inadequate. The possibility of condensation forming on glass may be minimised by using double glazed units with a low U Value, combined with a thermally broken glazing bar such as the Skyline, Skyline Box and Rafterline ranges.
For a more in-depth explanation of Condensation, the GGF (Glass & Glazing Federation) have published an interesting document, which can be viewed from this site.