…not the kind you have in your bathroom. I am talking about real frost, like the kind you want to have on your beer glass.
I was working on the 2nd floor which is not conditioned yet. Temperatures inside fell down to 25 Fahrenheit, and I began to notice something interesting.
The double hung window to the right is a regular double pane window with a U-factor of 0.48. These are the windows that were in the building when we bought it. As you can see, about three quarters of that window is frosted up to the point where you can’t see through it.
The glass surface of the window got so cold so quickly that the little moisture that was in the air condensed and froze in a heart beat. Imaging sitting next to a window like this during a cold evening. The cold glass surface would draw your body heat, making you feel cold and uncomfortable. And if the window is leaking air – well, you would probably opt to avoid the room altogether.
Let’s go back to the first picture above. The window to the right is one of our replacement windows, a triple pane insulated glazing unit (IGU’s). The awning at the top has a U-factor of 0.17, while the fixed casement at the bottom has a U-factor of 0.15. And – no condensation, no frost.
Well, I stand corrected. If you look very carefully in the bottom corners, you may be lucky to find a little bit of frost.
The bottom line is that the glass on this IGU does not get anywhere near as cold as on the regular double pane window, which explains the (almost) complete absence of condensation and frost. Sitting next to one of these IGU’s during a cold evening makes a world of difference. It doesn’t draw your body heat to the extent a regular double pane window would. You actually could sit there and feel comfortable.
I love running into this kind of anecdotal evidence!