Episode #8 Root Cellars, Wine Cellars and Cold Rooms Oh My!

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In this episode, Stephen will explain the differences between root cellars, wine cellars, and cold rooms so that you can ensure you can create the healthiest version of each. All three are erroneously thought to be the same, but as you will learn, they all have different requirements, and if done wrong, you could create problems for your wine, and for your family’s health.

The transcript for the show is here:

Welcome to Your Healthy House. I’m Stephen Collette

In this podcast, I explore your indoor environmental quality concerns and opportunities. We look at the facts and debunk the fiction. We will discuss examples you can relate to and the doable actions you can take in your own home or apartment. We will also look at the history of how our homes are, the way they are, and the future of healthy housing for everyone. I promise to make this fun and interesting for both of us.

Episode number eight, root cellars, wine cellars, and cold rooms, oh my! In this episode, I want to break down the differences between these three things. We commonly associate them to be this same, but in fact they’re quite different and required different conditions and those conditions when set up right, can be great for your vegetables, great for your wine, great for your preserves, or they can be really, really bad for your house and your air quality. So let’s jump into this and learn a little bit more about them.

The first one is the root cellar. That’s what we’ve always had since the Dawn of time. Since we started collecting vegetables and berries, we needed a place to put them in hopes that they would last longer than the season itself. So we dug a hole in the dirt underneath our homes and we put those fruits and vegetables that we harvested in there. Now here’s how it actually works from a science perspective. What’s going on is the fruits and vegetables need to be at a lower temperature. Now that temperature should be between 32 and 40 degrees Fahrenheit or zero and four degrees Celsius. By keeping your root cellar at this temperature, you’re going to slow down the decay process, the rotting of your fruits and vegetables, and help them last longer and longer through your winter season. So this is really important. Now also important is the relative humidity of that space. That’s the moisture in the air. What you really want for a root cellar is between 85 and 95% relative humidity. Now this is really high. This is what causes the problems in our homes, but not in our root cellars. Our homes can’t survive. At 85 to 95% relative humidity. That’s borderline rain. Okay? Now the root cellar needs it at that relative humidity because just like in your fridge, when the fruits and vegetables lose the moisture content, when they dry out, that’s actually the shriveling. So when you pull out that floppy carrot that’s all shriveled up, it’s actually just lost its moisture. And that’s why we put them in the crispers. Now the crispers help trap the moisture in the vegetables and fruits by being a little more airtight. And there’s a bit of circulation in there, uh, which you can control. And that regulates the amount of relative humidity in those crisper drawers to extend the life of your fruits and vegetables. And so that’s the purpose. So we want to do that in a root cellar as well. Now that comes in conflict with the fact that we don’t want those conditions within our homes. So typically speaking, if we go back a hundred years, 200 years, the root sellers may not have actually been inside our homes. They may have been outside of our homes, uh, dug into the side of a Hill or into the dirt or down under the near the garden, near the shed.

These were actually walking outdoor fridges, so to speak, that use the Earth’s temperature to keep it, uh, regulated, so below the Frostline. So we don’t want, uh, those kinds of conditions in our home, but we can safely have a root cellar in our home if we are managing and controlling that space and keeping it separate from our existing home. And so to do that, you’re going to really need to think about air barriers. You’re going to really need to think about vapor barriers. You’re going to really need to think about a airtight sealed insulated door between your root cellar and your home proper. And so by thinking those things and keeping them in mind, you can, uh, help create a healthier, a space for both you and your vegetables. Now the other thing that route sellers need is they need air circulation. And that’s because of the ethylene gas. So the ethylene gas is a byproduct of a rotting of aging. And there are fruits and vegetables that give off this ethylene gas such as apples and apricots and bananas. But there are also fruits and vegetables who were damaged by the ethylene gas and those can be asparagus and carrots and potatoes and cauliflowers. And so they’ll actually increase their breakdown when exposed to the ethylene gas given off by the other fruits and vegetables. So we need to isolate as much as possible the off gassers and those that are damaged by it, but some ventilation really helps. So do actually need air circulation within a root cellar and that can be, uh, easily a passive ventilation system, letting in air and, and exhausting air. It can be a powered fan. There are different options, but we just want to remember that we do actually need that ventilation to help prevent and slow down the route again. Okay.

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Now wine sellers are a different creature. Yes, we have fruits in there, but they’ve been fermented and they’re lying there in bottles waiting to be enjoyed. Now I do love working with clients who have wine sellers because they usually try to barter for those jobs. It makes it worth my while. Now wine cellars require different conditions than a root cellar. A wine cellar requires a relatively constant temperature as much as possible at around 55 degrees Fahrenheit or 13 degrees Celsius, and the more constant you can keep it, the better it is for the wine itself. The better at ages, the less variability and concerns with the chemistry going off inside the bottle itself. Now, the relative humidity is also different than a root cellar. The relative humidity for a wine cellar should be around 60 to 65% relative humidity, so that’s a lot lower than the root cellar.

By keeping the relative humidity at 60 to 65 you’re going to reduce the potential of the cork shriveling, which could cause a change in chemistry inside the wine bottle for the last several hundred years. These conditions were relatively easy to maintain in Europe and that’s because wine sellers were often located in Rocky basements where the relative humidity didn’t vary a whole lot and the temperature didn’t vary a whole lot because it was earth coupled. So the earth was a constant temperature. They didn’t necessarily get huge or deep frosts, and so these conditions were easy to maintain. Now for those of us who enjoy wine and want wine all year round, we need to help create these kinds of conditions if we’re purchasing a wine enjoy or as an investment, and so keeping the temperature 55 Fahrenheit, 13 degrees Celsius, 60 to 65% relative humidity, those are the ideal conditions. We also realize that those are not the ideal conditions, again, for us living in our homes. So we really need to think about separating those spaces and keeping them separate. Depending on your climate, you may need to cool a mechanically your wine cellar to help keep that temperature. You may also need to manage the humidity as most people will. And so that can be a full mechanical system doing both. They can be separate, again, depending on the size, the scale, um, and your, uh, environmental conditions. What you also want to think about again, is vapor movement, air movement, moisture movement between those two spaces, between your living space and your wine cellar. So again, you want to think about an airtight insulated door. If you’re doing something really magnificently fancy with wooden doors, you actually want to still make those air tight. You want to think about double-glazed a glass if you’re having glass doors into your wind cellar, because again, we’d just want to maintain the temperature and the differences between the two spaces.

The third type of space is a cold room. Most homes today may actually come with a cold room. If you live in a cold climate and have a basement and we’re going to see these cold rooms underneath your front porch. For example, this’ll be an area that has concrete, uh, maybe an insulated door and is not part of the living space proper. It’s underneath your front porch, your front deck. There may be some, uh, vents in it. And these are really common certainly in the Northern part of North America. So what’s a cold room for? Well, a cold room is actually shouldn’t really be for roots and vegetables. It shouldn’t really be for wine. It’s actually more purposefully used for preserves. So storing your jars of dill pickles and your pasta sauce and all those preserves, the jams, the jellies that you’ve been making. This is a really great place to store those. The temperature is cooler. The relative humidity can vary from indoors to outdoors, from condition space to this space. And those preserves aren’t going to be damaged or impacted. We’re just trying to keep them cooler. And you can put root vegetables in there, you can put some fruits in there, you can put your wine in there and your beer and whatever else you want, your cold drinks. All that works fine. But this is a more variable, unstable space for both temperature and relative humidity. And we need to really understand that because this is where we can get into trouble. Okay, so you can see that these three spaces are oftentimes the same space in our homes, but they require very, very different conditions. And if we are attempting to do one of three great, the other two are going to end up poor. And that’s where we usually are because we simply refer to our cold room as everything and everything goes in there. And that’s where we start to get problems with water and moisture and mold. That’s because the variability in the temperature and in the relative humidity in our cold rooms creates the potential for condensation due point. That’s where the water turns from a vapor into a liquid and that’s because it’s damp in that space. And as the temperature drops, the air can’t hold any more water than the water physically falls out and that’s what’s going on in most cold rooms. The other thing that we do is we just see the cold room as another storage space because we have so much junk, we just need a place to put the junk and I don’t want to see the junk, so we put it in there so we can close the door and it goes away and we don’t think about it. And I’ve seen cold rooms absolutely packed to the top full of boxes, full of mattresses, full of memories, full of everything.

Now remember when we have things that are made of cellulose, paper and cardboard specifically, and we have dust because of spaces and clean very often because it’s fall, we’re going to get the strong likelihood of mold happening. Okay, so in an existing home, if you have a cold room, you really should only be using it for food stuffs. You should only really have plastic metal and glass in there or the vegetables themselves. If you’re storing fruits and veggies, they should be off the floor. Ideally on shelves or racks so that we can get some air circulation around them to reduce the ethylene. If you’re storing wine in there, you want to put them in a rack. So they’re laying on their sides and if you’re just storing your preserves, that’s fine. They can tolerate those variations, but no cardboard, nothing that can grow mold in there.

So we really want to minimize that for sure. Now, what have you want to build something? What if you want to make one of these root cellars? Wine sellers are a cold room and you don’t have that space right now. Well, that’s doable. We can think about that and we can do it. Now, this is oftentimes going to be a basement, so for those who don’t have basements, you’re probably going to look at an and an outside sort of space, maybe like an outside a building or underground. But for those with basements you can think about trying to partition off one corner of your basement. So I recommend a corner because you can insulate two walls on the interior and use the exterior two walls of a corner and keep them on insulated and that’s going to lower the overall temperature of that space because now you’re a little more earth coupled, so the temperature of that cold concrete walls are going to help lower the temperature within that space.

By insulating the interior two walls, you can create a cold room without negatively impacting the rest of the house. Now, depending on what you’re using it for, we want to think about, you know how big this is going to be. Obviously if it’s a walk in wine cellar, this is a little different. You’re going to stretch that out a fair bit, but the more you can earth couple, the easier it is to control the temperatures because they’re going to be lower. If we don’t have that opportunity, then you may have to look at mechanical mechanically controlling the temperature and relative humidity in that space at least more than if you were earth coupled with a couple exterior walls. So keeping that in mind by insulating. Now if it’s just a cold room for some potatoes and some wine and some preserves, but you’re not really critical about it, I would recommend keeping it open to the inside.

So that would mean undercutting the door. That would mean maybe keeping the joist cavities open so that there can be some air circulation in there and that’ll help keep them the fruits and vegetables. But it’s basically a cool conditioned space. And that’s one way to treat your cold room. The second way to treat a cold room is to absolutely make it air tight from the and insulated from the conditioned space. So they’re two separate spaces and independent of each other. That requires some thinking because of dewpoint, because of condensation, because of moisture and air circulation. And typically you’re going to do that with a bigger project versus like a small little closet. So I have a cold room in my home. It’s a 1950s basement. My cold rooms about six and a half feet long. It’s about two and a half feet wide with a door in the middle. So it’s relatively small, but I just have it for shelves. So I have shelves with preserves on it. I have shelves with a wine and with beer and I have, uh, on the cross, the floor is up on a lifted up is all have some fruits and vegetables there as well. And that serves our small scale purposes. And that can be a fine thing. I have the door undercuts, I have the joists cavities open, so there’s ventilation and that’s how that one’s approached. [inaudible] if you were going to do the exact same thing and you wanted it airtight, you would air seal everything, make sure the door is insulated and weather stripped. And maybe you would put in a humidistat or a bathroom fan with a built in humidistat. And these are really common. Now we can get these almost anywhere. They used to be really difficult to get. You had to get a humidistat switch, but now we can buy a bathroom fan that has a built in humidistat and you can set it on some of them, uh, so that if it exceeds a certain amount of humidity, it’ll automatically come on and suck the air. And that would pull air from uh, the cracks in the crevices and that air circulation would lower your overall humidity. And that’s a great way to manage any of these systems. Now the root cellar probably doesn’t need it cause you can take almost a hundred percent. So keeping that in mind, there are some tools for building new, such as humid a stats that will turn on exhaust fans to help maintain a, your relative humidity at the desired setting. You want to think about building materials, especially if you’re building like a walk in a wine cellar because that’s usually where people are going to spend the money.

You want to think about the building materials that are going to be able to handle those exposures and those, uh, humidity and temperature levels and still be durable. So you definitely want to lean towards more solid woods and less particle boards. You want to be really detailed on your air ceiling and your vapor control. And then look at mechanical controls where necessary. If it’s just a cold room, you can be a little more variable, but keep the crap out of it. So it’s not going to grow mold. If it’s a root cellar, you need to really make sure you’re isolating that space from the rest of the house because that is ideal mold conditions inside your building envelope. So if you’re doing it inside, you have to really manage it successfully. And one of the ways on a new construction you would manage that is again thinking about uh, like an exterior corner, but maybe you don’t even pour the concrete floor in that location. And that having graveled there would really help them manage the moisture, but it also really lower the temperature quite a lot. And that would be one way. And then air seal and insulate around that space. Now in existing homes that have a cold room built into them, these are going to be the biggest challenges because they often come with passive ventilation installed, which means there’s two air events open to the outside inside these cold rooms. And these can be very damaging to the building because what happens is in the summer, the hot, moist, humid air is literally pouring into this space. So it’s filling it full of moist air. And if we’re not managing that, the concrete will take on that load. And then in the winter time, that can be a cop trying to come out. Now if the concrete can take it or if you’ve got easier materials such as cardboard and paper and dust, they’re going to take on that moisture content and that’s what’s going to grow mold in the winter time. Those passive vents are simply pouring, freezing cold air into your house. And if your door between your cold room and the rest of the house isn’t airtight, that’s super terrible, right? That’s pouring in. You’re losing energy dollars dramatically. Also from a stack effect, from a chimney effect, from a building pressure system, that’s where the air is coming into the house as your energy dollars go up and out through your attic hatch. So these passive vents can be really damaging and I typically don’t recommend passive vents in cold climates. I recommend you simply air seal them up the simplest way. It could be with some spray foam that’s a little toxic. You can even use a bag, like a grocery bag filled with insulation, just shove it in. So the insulation is your thermal barrier, the plastic bags, your air barrier. Um, you can tape it over, you can insulate it, but we need to make sure that we have in thermal insulation and air tightness at the same time.

So those are the tips and tricks. When we’re looking at root cellars, wine sellers and cold rooms, they are a little different. So you have to do a little research and figure out what you want to do, what’s important to you, how you’re going to create that space, make it safe so that whatever you’re storing in there is that ideal temperatures and humidity. So it can survive long periods. But we also want to make sure that we’re not damaging the rest of the house negatively by allowing moist air into it and causing damage. Thanks for listening.


If you enjoy this show, please leave a review and subscribe to the podcast and you will be doing your part to help others create their own healthy homes. If you’d like to learn more about me, Stephen Collette, and what I do, please check out my website at your healthy house dot. C a music for the podcast is by Brian Pickett of Voodoo Highway Music audio technical support is by Mike Pickett. Editorial support is by Eric Rosen. I’m your host, Stephen Collette. Thanks for listening and enjoy your day. Cheers.