#AskDerekCole Episode 91
28 Jan 2026 · 7 min
Derek Cole answers why upstairs rooms get hotter than downstairs and why indoor air quality can be worse than outside. He recommends zoning your HVAC system over adding a second unit, and explains how VOC off-gassing from building materials and poor ventilation in tight homes degrade indoor air.
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Hey, on this episode, we talk about why is my upstairs hotter than my downstairs? And why is my indoor air worse than outside? You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, everybody, this is Derek Cole. Welcome to episode 91 of the Ask Derrick Cole Show. Answering our home energy questions. And yes, I'm aware there's something on my face right about here. I literally ran into a door and the door won. Do you want me to zoom into it? Sorry. I'm self conscious enough. Why is my upstairs hotter than downstairs? I have one unit that covers both. The problem with one unit covering both is that you have different demands upstairs than you have downstairs. So. So when you look at a house and think about it, heat rises, obviously, right? So when he rises upstairs, typically would be warmer than downstairs. Right? So chances are I've seen this before. The thermostat is downstairs. You have a unit that runs the whole house up and down. So to get upstairs comfortable, you then have to make downstairs freezing. When I first got married, we lived in an apartment that was two stories but had one unit. So I mean, when you went downstairs at nighttime, it was like, you better put on like a big coat and everything because it can't happen. Because upstairs you have more of a load than you have downstairs. Downstairs heat rises. You also have the attic upstairs. So you have these forces you're going against. You have the attic, you have windows, you have upstairs heat rises downstairs, of course, cold air falls and you don't have an attic downstairs. And the crawl space is not that much of a heat load compared to an attic. So it's different demand. So how you solve that problem is either two units or what we've done quite a few times, which is zoning. You make downstairs one zone, you make upstairs one zone. It's very simple. If you have a unit that covers up and downstairs right now, you can very simply make it a two zone system. That way you have a thermostat downstairs, you have a thermostat upstairs. You can keep it that temperature you want, you can keep it that temperature you want, and they can make it work that way. So the challenge with some houses is that there is not that duct chase in the house for the duct to be run to have one unit for the whole home. But if you already have that, obviously that's available, but you just need to make it a zoning situation. I wouldn't get two units. I would just zone it upstairs, downstairs, and that will solve the problem. But until you do that it is what it is. I mean, the thermostat downstairs upstairs is warmer. In the summertime, it's going to be. So you just might have to freeze it out downstairs and get upstairs as comfortable as possible. Why is indoor air worse than outdoor air? We kind of got in this with the radio this week, but the EPA says indoor air is two to five times worse than outdoor air. Why is that possible? Why is that happening? The reason why is because of this desk, the carpet, the paint, everything on the wall. All of these are what they call VOCs, volatile organic compounds. Since we made our homes tighter and our businesses tighter, more energy efficient, these chemicals off gassing cannot escape the space anymore, right? So now you're breathing it in your lungs. Outside, you don't have that present. You have ozone. You have uv, you have Mother Nature fighting against what's naturally present, and it's doing what it does in the home. You don't have that going on. You have these paints and finishes and carpets and stains. All this stuff. You have this compressed wood that's glued together. All the stuff's off gassing, and you're allergic to it because there's nowhere for it to go. Because the homes are so energy efficient, which is good, saving you money on energy. But the bad thing is you don't have fresh air, you don't have clean air. You now have the same air that, you know, off gases, all this stuff. So how do you solve that problem? Right? How do you solve that problem? You bring in what happens outside, inside your home. UV ozone. Those products we can put inside your system. UV light, UVV ozone inside your system. Ozone's only responsibility in life to find a gas molecule and kill it, destroy it. That's all ozone is available for. That's why when it, when it just rains, it smells really good outside. You're like, oh, it's nice and fresh. That's great. Well, it's called ozone. That's what it's called. It's because that can be in your house. And no. Yes, ozone is dangerous at the wrong levels. What do we do in your house is a lower ozone than what is outside. So I just took Tylenol. If I took a whole bottle of Tylenol, I would die, probably, right? If I take what I'm supposed to take, I'll feel better. So ozone in the right levels is fine. The same thing as the chemicals you put in the pool. Chlorine. If you put 100% chlorine, it's going to kill all the algae in the pool. The problem is you can't swim in it. That is a problem. So what happens, you put in a little bit or tablets on top or. Or you have the thing near the bottom and you fill it up and it. It puts a little chlorine in. Same with ozone. So yes, it is dangerous at the wrong levels, but so is water, so is Tylenol. Everything is dangerous at the wrong levels. I mean, you can literally drown. But too much water intake, right? But you supposed to have water for life. So at the wrong levels, bad. At the right levels, good. So we can bring in what's outside, ozone, UV into your home and solve that problem. So a lot of people are allergic to. They're allergic to their homes because all these chemicals and gases and. And they're taking algae medicines and Claritin and to try mask over these symptoms. I'm not saying we're curing diseases here, but I'm saying that a lot of things that people are allergic to are things that can be controlled. So you need to see what's going on there. Get a better filter, get uv, get ozone inside the house and that stops the problem. That was a long rant, wasn't it? All right, it's episode 91 of the Ask Derek Cole Show. Any questions, please hashtag them, Ask Derek Cole, and we'll get them on the show.
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