 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 a 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.