I know there are a ton of wine cellar threads but I cannot figure out if my question isn’t covered or if I just can’t phrase the search specifically enough to get an exact hit. So… Can I roughly estimate the temp of a passive wine cellar by taking periodic readings of the current basement floor temp throughout the summer? I’m trying to determine if I need to build active storage or if I can get away with passive.
Another quick question: Do I need vapor barrier for passive storage, or is that just required for active storage?
Hard to tell regarding estimation. Depends heavily on things like outside temperature and swings (day/night) how deep the floor is under the ground, how much of the upper basement space is above ground, where the room is located (north/south) adjacency to windows, thickness of exterior walls…
And floor temp is your best bet. In my passive cellar I can see around 0.2 °C difference for every 10cm vertically. So a basic IKEA rack with 3 “floors” might see a temp of 17 °C at bottom and 17.3-17.4 °C at top.
You’d also need to check the temp throughout the year. Some people see very small differences between winter and summer, depending on factors listed above. In my case the gradual swing is pretty significant, with coldest winter temps at about 11.5 °C (52 F) to about 20 °C (68 F) in hottest summer weeks.
Vapor barrier would only be needed in case you decide to insulate everything and add an active cooling unit I think, unless there’s extreme humidity in the room.
I’m going to go get an infrared thermometer and check the temp of the basement floor. It is very cool in the open basement (~65) right now, so I’m thinking the floor itself must be even cooler than that, and if I insulate off a small room for a cellar I’ll be in good shape going passive. But instead of guessing I should probably start taking some basement floor readings through the rest of this summer.
you should be taking the temp of liquid in the cellar, not the air. if the floor is the coldest then you can harness that by insulating the rest and adding a small fan to circulate the air.
edit as for humidity, you don’t mention where this is, but for example in the NE usa, a below grade basement will be humid in the summer and dry in the winter.
Right now what I want to do is decide whether to build a passive or active cellar. So I’m wondering if I can take the temp of the basement floor through the warmest parts of this summer to inform my decision. The cellar will be built sometime between October and December.
If I do go passive, I will leave the floor uninsulated and insulate all the walls and ceiling. (Closing off a 10’ x 10’ section, roughly.)
i had this setup for 20 years in philadelphia. i did put in a cooling unit, but it only ran for 2 months of the year.
a PID-based thermostat plug attached to the smallest / cheapest manual AC is by far more than you’ll ever likely need, and significantly cheaper than a wine unit. but that depends on how your basement is set up, noise, etc.
My cellar cooler uses a probe in a bottle of water, which I locate fairly high up in the cellar racks so a worst case will be covered. I’d suggest using a thermometer in a bottle of water placed at various heights to properly map what you have before creating the cellar.
I understand using the probe in water to measure actual temp swings once the cellar is built. But I’m not sure how informative it will be regarding making a decision this fall between building passive or active in the first place. I assume a passive cellar built correctly and insulated like crazy will be much cooler and more stable than my current basement temps. And I’m hoping that the current basement floor temps would be the best barometer of what I can expect in a properly insulated passive when cellar built over that floor. But I’m not really sure if that is true or not, and was hoping some folks here would know.
The point of using a bottle of water for the probe is to damp out fluctuations - you can get bit changes by opening a door and walking into a room in some cases whereas the probe in the bottle set up pretty much eliminates that.
If the room has no one going in or out I suggest that you get a thermometer with a remote probe, i.e. on a long wire. I use a Micronta that can have the probe places something like 3-4 feet away from the instrument and it records high and low temp at whatever height it is placed at. Do that for both high and low placements and you’ll get a very good idea of what is going on in the room as is and whether it changes much.
After we insulated the room that top-bottom variance was only about 2 deg. at most.
“If the deep soil temperature at your site is above 60°F (16°C), then a passively cooled wine cellar is not possible no matter how far down you dig. The one exception is when an extremely dry climate permits you to utilize evaporative cooling, described in chapter 10. Even 60°F (16°C) is often too warm. The constant deep-soil temperature must be several degrees cooler than the highest acceptable cellar temperature, because some annual temperature cycle is unavoidable.
“If your climate is snow free most of the year, then the deep soil temperature will precisely equal the average annual above ground temperature. If the ground carries a snow blanket for part of the winter, then the snow will insulate against soil-to-air heat loss because snow is 901 air pockets, and the annually averaged deep soil temperature will be a few degrees warmer than the annually averaged air temperature.”
— How and Why to Build a Wine Cellar, Fourth Edition by Richard M. Gold
If you are even considering a passive cellar, you really should purchase a copy of Gold’s book for reference. It’s the most in depth resource that exists on the subject (that I know of).
I understand that. But I don’t care about the temperature of the greater basement at this point in time. I am going to section off and insulate a portion of the basement for the cellar. I assumed (but am probably wrong given the pushback that I’m getting on it) that the temp of the basement floor over the summer months will be much more informative than the temp of the greater basement in regards to how the smaller insulated room would perform.
I have an outside condenser and the line runs into the basement where it ties into the HVAC system, if that’s what you mean?
Just checked the basement floor and it’s 61 degrees over most of it. I was hoping it was a bit colder as everybody says it will slowly warm over the summer and around September it will likely be at it’s warmest. I suppose since I’m reading the inside surface of the basement floor, ambient air could be warming it a bit, making it a bit warmer than it would be once the cellar is built and insulated from the rest of the basement? (Maybe wishful thinking?)
