We finally decided we had enough with the heat, so we ordered an air conditioner off of Amazon. The problem was, this one was designed for vertically sliding windows, something we didn't realize until we tried to install it in our horizontally-sliding casement* window. As I looked at other people's creative solutions, I came up with this. Three days and going strong, so at this point, it looks like a success.

*Edit: D. Reichart pointed out to me that this is not actually a casement window. Casement windows are the ones that crank open. My apologies.

I feel I've gotta expand on my disclaimer -- please think about my design before using it in your situation. I'm sure the manufacturer would say this is a stupid idea, so proceed at your own peril. It hasn't blown up or fallen out of the window -- yet -- but I haven't thoroughly tested this. In other words, don't blame me if something goes wrong. These things are heavy!

Ingredients:
Air conditioner

One 6-8 foot 2"x2"
One 3-4 foot of 1"x4"
One package Command Adhesive Velcro strips
One 1.5" screw
A piece of plexiglass that fills the area above the AC unit
Masking tape, or something like it
Foam, if your air conditioner didn't come with any

Please forgive the choppy editing -- I got a new camera, and my video editing software isn't playing nice with the files, so I had to use Windows Movie Maker.

1-Year Update:
We finally installed it for its second summer of use (I love Oregon). It would have gone very quickly, but we needed more foam to fill the gaps, so I had to run to the store. But the installation was very easy. I just had to go back and rewatch the video to make sure I was doing it right!

2-Year Update:
Installed it again after rewatching the video as a refresher. Still no changes in the techniques I used the first year. The hardest part was washing the second story windows; other than that, it was just a matter of following directions, cutting the foam to size, and enjoying the cool air. Everything still seems to be as solid as ever!

3-Year Update:
It only took about half an hour this year, and that's with a hurt shoulder. All we bought this year was some new foam, and we were golden.

4-Year Update:
Ours went in no problem, and we still had time in the same evening to build and install a new one for a relative.

5-Year Update:
Both the relative's AC and mine are still rock solid. There was some paint loss on the window ledge of the relative's apartment (crappy paint), but with enough Command Adhesive, we got it stuck down.

Times people took my 80 degree comment seriously or comment on how hot it gets where they live: 62