We did a fair amount of renovations to our current home before we moved in (about 2 years ago). I knew I wanted to install a whole house fan. Instead of putting it into the standard location of the 2nd floor hallway ceiling, I put it in the ceiling of my office (spare 2nd floor bedroom). Works just fine as house fan there, but if I close the door, close the HVAC vent, and open the window a bit, I can smoke in there all I want with no lingering odor issues afterwards. The price to pay is it can get a little cold/hot depending in the season, but it’s pulling in enough house air under the door that it’s always reasonably comfortable if the outside temp is between about 30 and 85. Of course, it requires an attic (with sufficient ventilation), so that may not work for your new room. It has insulated flaps that fall closed when the fan is off. The motor itself is well inside the attic, which cuts down on noise. Could also be overkill for just one room, and much more expensive than just a powerful bathroom fan.
It is definitely more efficient at cooling the house than the AC though. Mines centered in the middle point of my home though.
