706. Hot Upstairs? Here's Why. Plus the Truth About Your Indoor Air Quality
30 Jun 2026 · 8 min
Derek Cole explains why upstairs rooms get hotter than downstairs in single-unit HVAC systems and why indoor air can be two to five times more polluted than outside air. Heat rises, attics add thermal load, and thermostats are usually downstairs. Indoor pollution comes from off-gassing VOCs in paints, carpets, and engineered wood, especially in tight homes. Two-zone systems or higher-efficiency filters and UV light can fix both problems.
Chapters
Home and Life Comfort with Derek Cole. 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 Derek Cole Show. Hey everybody, this is Derek Cole. Welcome to episode 91 of the Ask Derek Cole Show, answering your home energy questions. And yes, I am 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? No, 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 when you look at a house and think about it, heat rises, obviously, right? So when heat rises upstairs, typically will 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 2 stories but had 1 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 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 and downstairs, of course, cold air falls. And you don't have an attic downstairs, so you do— 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 2 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 keep it that temperature you want, and they can make it work that way. So, uh, the challenge with some houses is that there is not that duck chase in the house for the duck 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 into this with the radio this week, but the EPA says indoor air is 2 to 5 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 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 this 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, all the 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 is to find the 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, ah, it's great. Well, it's called ozone. That's what it's called. It's because that can be in your house. And no, oh yes, ozone is dangerous at the wrong levels. What do we do in your house? Is 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, uh, 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 the tablets on top, or, or you have the thing at 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're 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 allergy medicines and Claritin and They're trying to 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? Alright, it's episode 91 of the #AskDerekCole Show. Any questions, please hashtag them #AskDerekCole and we'll get them on the show. Home and life comfort with Derek Cole.
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