Not an issue. There's a little coming out on an angle from the front vent, which you might notice if your projector is at table height, and you were sitting a couple of feet away, and just forward and to the right of it. Of course, if you sat right there, you'ld also get hit by the hot air coming out of that same exhaust vent.
HC1080UB Audible Noise Levels
Ahh, this has never been the Epson's strength. While most LCD projectors are very quiet, in fact, all the quietest projectors are LCD models, the Epson is noisier than most of the LCD competition, and is almost as loud as the typical DLP projector.
Let me translate. Epson claims a very quiet 26db in low lamp mode, and that number is very believable. No one should have an issue when the projector is in its less bright lamp mode. Epson, I don't believe, publishes a spec for the brighter lamp mode, but, based on "listening" to other projectors, I'd put it in the 30 - 32 db range. 30 db to about 34 db, is typical for most DLP projectors in their bright modes, along with the JVC RS1 and RS2, which are similar to the Epson. Let's say that the Epson Home Cinema 1080UB is about 2-3 db quieter than the typical DLP home theater projector, not a lot, but everything helps. I should also mention, that its fan noise is a little lower pitched than most DLP projectors, in part because they have as part of their noise component, their high speed spinning color wheels which tend to be higher pitched.
Bottom line: Those most sensitive (annoyed) with any noise levels, will take issue with the Epson with the fan on bright, and for a few, it might be a deal breaker. Just remember, the actual noise level is going to be quieter than, say, the air blowing through your home's vents for air conditioning or hot air heating. I don't suppose anyone is going to turn off their heating/cooling systems, just to watch a movie
HC1080UBProjector Screen Recommendations
The better the projector, the better it is able to work with a wide range of screen surfaces. I have never spent as much time watching a projector for a review - almost 80 hours! Most of that has been on my Firehawk G3, and In almost all cases, I was filling the full screen. (For fun, we opened a number of shades and used Dynamic mode for football one day, but reduced the image size to about 100 inches.)
The Firehawk G3 (or the Firehawk SST if you are ceiling mounting the Epson close, work spectacularly with the HC1080UB. It keeps the blacks looking very black, and it's HC (high contrast) aspects, I think, add to the "wow". I did however, spend a fair amount of time watching the Epson perform in my testing room, on the Carada Brilliant White (filling just about the whole 106" diagonal), as well as less time on an Elite accoustic screen that I'm reviewing, as well as a standard matte white surface.
With the Carada, which is smaller, I ended up with an extremely bright image. Even so, the superior blacks of the HC1080UB, remained dark enough to please (I think), all but the hard core black level fanatics. Obviously the blacks were a lighter gray, than on the larger, darker Firehawk, but the Epson's blacks are such, that it still kept those black levels down around what I would expect a lesser 1080p projector to do on darker surfaced, larger screens.
My recommendation is to primarily match your screen choice to your room situation, for both movie and HDTV/Sports viewing. If you've got some ambient light issues, go for the HC Gray like the Firehawk, any number of Da-lite, Elite, and other brand HC gray screens. if your room is the proverbial cave, with dark walls, ceilings, etc. you can go white surface, with or without extra gain, depending on your preferences.