Derek Cole argues against Energy Star's advice to raise your thermostat when away. Pushing it above 78 °F forces your HVAC to work harder when you return and can spike indoor humidity to 60-70%, risking mold. Keep it constant in regularly used spaces, or raise it only for rooms empty for weeks or months.
Can I allow the upstairs to heat up even more during the day and cool the downstairs less at night?
Hey, I don't know where you're going with that question, but again, I would— according to Energy Star, they want you to raise the temperature while you're away from home and then lower it back when you get home. My personal recommendation is to leave it at a constant temperature. That's what I do. That's what I find to be good because— and here's why— if it's a 95-degree day and you go from 75 to 78 when you leave, and then you get home at 5:30 and you crank it down to 75, that unit's going to run at least a couple hours trying to get down to that temperature because now everything in your home is 78 degrees. So now you want everything to be 75. Well, we got two challenges. One, you're running on high speed. If you have a two-speed system, you're running on high, which is not the most economical way to do it. And everything in the home has to be cooled down. It's 5:30, it's 6 o'clock, you're cooking dinner, it's coming off of the hottest part of the day at 4. So it's having a hard time getting that temperature. So I I would not set anything unless you're leaving that room for an extended period of time, then I would put it on 78. If we're not going to go upstairs for 2 months, I would leave the temperature at 78. If it's something you use every single day, then I would leave it at the temperature you want. At my house, I crank it down a little bit at nighttime because I like it nice and chilly. But then again, it's, you know, it's 9:30, 10 o'clock at night when I'm asking it to get down in temperature. So the sun is gone, the heat is gone, so now we're just mainly dehumidifying and getting that temperature back down. So I would not, I would not recommend that. Now the nice people at Energy Star say this is completely wrong. What you should do is leave it up while you're gone, bring it down when you get home, You know what? I don't do it. I don't recommend it. It's just, to me, not the most economical way to do it. Because if I leave my house at 78 for 8 hours and I come home for another 8 hours and put it at 75, am I saving anything by not keeping it 75 all day long? I don't think I am, because now we're having to crank up a high speed. To get down to 75 when I get home. And when the rare occasion happens that there's cooking in my house, now you get an oven and a stove and you got to overcome that kind of heat from everything up in there. So I would not, no, I would not do it. And even still, I will add on to that question a little bit. If you do have a bonus room that you don't visit a whole lot, I've seen quite a few houses where we go to and it's you know, 80, 85 degrees on a thermostat. Um, you don't want it that high. You don't want it above 78 because really in this part of the country you're trying to control humidity. And when you put 80, 85 on a thermostat, that humidity in that room is getting up to 60, 70% possibly. And then you start growing organic things that you want in that room So at 75, you keep into that 30 to 50% humidity, which will not let anything start growing with it in your space, in your walls, behind your walls, things you don't want to happen. So I understand you're not in that room, but at the same time, you don't want that room to be a problem.
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