Are northerners born in fridges?

You might be underestimating how extreme the weather gets in the American North. During the summer it'll be over 100F heat index for 3-4 months, but then in the winter the wind chill will fall as low as -45 (take your pick on units because that's a point of parity for Celsius and Fahrenheit) personally I'm uncomfortable once it gets over 70F but even when the temperature plunges into the deep negatives, you just bundle up and limit your time outside and it's not too bad. It doesn't feel much colder at -20 than it does at -5, but 90 and 110 degree heat indexes definitely feel significantly different. Climate change destabilizing the polar vortex is clearly making the extreme cold practically an annual occurrence now.

On the subject of Texas, if you were visiting a region with high humidity that may well be why the AC was running so hard. I'm not sure if the mold risk is universal or far lower for a stone structures but high humidity can ruin structures and make you very sick by incubating mold. Also modern structures are designed to be heavily insulated to the point where artificial ventilation is needed to replace stale CO2 rich air, which also means the interior needs to be regulated since it won't just breath with the outside to correct like older structures, so trapped moisture will remain trapped and fester