 So if your heat in the day won't keep under 80 degrees and you want it at 75, maybe if you drop down five degrees earlier, it'll help you keep it cooler longer. Now, it will be cold in the mornings, and that's one of those challenges. Now, another side note on this, if you're putting in a new HVAC system in, talk to your HVAC professional about going through and doing a zone system. And that's what I did in my house.