This winter I have kept my house thermostat on 63-64 and simply wear an extra layer indoors. Even though this winter is the coldest in my area in 10-11 years, I am finding that I am handling the cold temps outdoors much better that previous years. It seems like, if you keep the indoor thermostat to high, your body forgets how to adjust to changing temperatures. I am sure that the opposite would be true in summer. If you keep the air conditioning on too cold, one would have a harder time with jaunts outdoors.