Ziggo 5, computer or space heater?

The other night about a week ago it was extremely warm in my tiny apartment. This was when I was doing preliminary testing of Z5 running it at full throttle and trying to get the case cooling into order. The temperature outside was 55f and the temperature inside was 90f. The only thing I can think to blame is the hot air being constantly blasted out the top and back of Z5. After a few days of tweaking I figure I'm not going to get it to run any cooler but what I can do is improve the airflow in my apartment maybe. What I'm thinking about is a 5 inch by 5 inch square channel that will run along the wall and direct warm computer exhaust air right out a window that already has a fan in it. I've already mocked up a 5x5 channel that's about 6 feet long but with no bottom (like an upside-down U shape) and hung that on the wall using double stick tape. Using foam core and double stick tape should definitely work but the upside-down U channel seems to leak alot of heat so having a sealed channel will be necessary. The last thing I want or need is for it to get up over 100 degrees inside when it's 80 degrees outside! I can't wait to see my next electric bill...