It's great that you're asking questions! I wish I had a better answer for you on this one. I'm in southern California and live in a top-floor apartment that stays pretty warm (plus I get cold stupidly easily, so my comfort zone of 75-78 F is actually pretty close to what my snakes prefer anyway), so I've never needed anything other than the UTH for the hotspot. In the summer, the A/C has to work constantly just to keep indoor temps from cresting above 80 F anyway, and in winter, I bust out a small space heater if I need a particular room to be a little warmer.