Options
2012
Conference Paper
Titel
Condensation on the outside surface of window glazing
Titel Supplements
What are the key parameters and how to avoid with Low-E coating?
Abstract
The market share of triple heat insulating glazing has been increasing to ~60 % by now in Germany. Dew and frost on the outside surface of such insulating glass units with Ug values from 0.4 to 1.0 W/m2K installed as window glazing are a severe problem, because the free look-through being one of the essential functions of glazing is disturbed. This report describes the kay parameters influencing the occurrence. Therefore a realistic model of the stationary heat flow through glazing is established. From this parameter study it follows that frost can be avoided by adequate Low-E, but this does not hold for dew. Regarding dew, only the frequency of its occurrence can be diminished. The essential result of the study is that dew on the outside surface of glazing cannot be avoided with any Low-E coating if the outdoor temperature exceeds the room temperature. With Low-E coatings having a maximum emissivity epsilon0 = 0.2 marketed today frost can be avoided on the outside surface of all vertically installed glazing with Ug greater-than-or-equal 0.6 W/m2K and on the outside of skylight glazing with Ug greater-than-or-equal 0.75 W/m2K.