I have a barn style house. The upstairs ceilings & walls are shaped just like the roof w/slants. I do not have an attic. I live in Texas and during the summer, our upstairs is a sauna. I was thinking of getting some type of vent to install in the upstairs hallway to suck out the hot air during the day while we're gone to work. Any ideas how to go about this and what kind of vent to use? I do not have any gables, or vents in my roof, outside walls or awnings. Not worried about noise from the fan... just making it weather-proof and user controlled. Thanks in advance for any ideas.

You need some kind of turbine type vents. Check at Lowe's or Home Depot and see what they recommend. You also need some type that close in cold weather.