Window Frosting

Frost on the Pane
This is frost on our front door. It’s supposed to be a really well insulated door and glazing with argon but I’m not impressed with the commercial varieties. They frost up all too easily when it gets deeply sub-zero here.

This year we have a variety of test panes to observe in the tiny cottage. Last fall Ben and I took several of our large windows apart and installed film between them to make super windows. I’ve been meaning to do this since we built the cottage but it hadn’t gotten to the top of my to-do list yet.†

To improve windows I put panes of heat shrink Tedlar film on frames between the glass panes. The hard glass protects the fragile Tedlar layers. The Tedlar layers are spaced 1/4″ to 1″ apart to create insulating static air buffers dramatically improving the insulation value of the windows while preserving the view.

So with several windows insulated at one pane, two panes, three panes, four panes and six panes and super cold weather I have gotten to observe how they do. Four panes is sufficient, except for when the windchill drops it to -90°F. To deal with that I really need to add a shutter on the outside perhaps of polycarbonate twinwall. That still lets light in but obstructs the view. I may do that on the east and west windows. We have no windows on the north and the wind does not hit the south side so I would be incline to leave that unobstructed.

The Tedlar is very long lasting. In the old farm house I have some that is 25 years old in one of my original permanent super window tests and it still looks just as good today as when I built it.

Just as importantly, it’s cheap and an easy Do-It-Yourself project. The commercial thermopane windows cost $500 to $1,000. I can built the super windows using cheap salvaged single pane glass and Tedlar for about $25 each.

The downside is my better windows don’t create the beautiful frost patterns that entertain us in the winter’s light.[1, 2, 3, 4, 5]

Outdoors: 24°F/-4°F Overcast, 4″ Snow
Tiny Cottage: 51°F/59°F

Daily Spark: When it gets this cold we console ourselves that it can only get warmer…

^†I’ll be living another thousand years at this rate…