I’m planning something similar. Currently the wine I intend to drink in the next 6-12 months is stored in a 300 square foot basement room (my wine bought for aging is in an off site) that stays within a range of appropriate temps, but I want to reduce the temperature and humidity swings and potential for light exposure. I intend to wall off approx 100 sq ft that will have three basement foundation walls that are fully undergrade so that I can bring all my wine to the house.
What type of construction and insulation did you use for your enclosing wall?
I’m thinking a 2x6 wall across, 2x4 walls across the basement foundation walls and then insulation with spray foam insulation to provide both a vapor barrier and insulation. I’d like to stay passive as living in a nearly 100 year old house can present challenges when a need for running new electrical and venting arises.
Gold’s book (which I cited in post #15 above) is an exhaustive (and exhausting at points) guide to passive cellars. I ordered it on Amazon.
Your plan sounds pretty good, based on my reading. I’m working on something similar.
The non-obvious things I learned from Gold were:
(1) Ground temperature varies more than you think and in the summer it can reach 60F+ even five feet below ground in the northeast US. I’d assumed the walls in my subgrade room would stay well below 60F even year round.
(2) Consequently, the floor will be your greatest friend in maintaining even temperatures (assuming you’ve insulated the hell out of the ceiling and the walls facing the rest of the basement). That means you don’t want too small a room, or the ratio of the floor to the walls will be too small.
(3) Concrete conducts heat more than you might think. Foundation walls can carry that 60F temperature in the upper soil down to the base of the wall, and the concrete floor will conduct heat from warmer parts of the basement.
(Gold recommends building a two- or three-foot shelf of insulation out from the foundation wall several feet below the surface to keep the warm surface soil from transmitting heat down to the base of your foundation wall. He acknowledges that this is nearly impossible if the house has already been built. As I said, his book can be exhausting!)
I checked last night and it was 28f, I could see the half bottles of Sauternes we’re getting a little cloudy so I left the cellar door open. It’s sitting at 33f now and the Sauternes have cleared up.
I checked for protruding corks and saw none, so I’m good. My cellar usually limits out at 38f in the dead of winter.
My passive cellar had been holding 51-52F most of this winter here in Nebraska but with outdoor temps of 0F during the day and -16F at night this week my cellar dropped to 47-48F. Not really that worried about it. Get more concerned during the summer when it peaks out at 67-68F in the hot summer months hoping it won’t go higher.
28F is a little scary. But, ordinary dry wine freezes around 20F, so I’d think that the higher alcohol and sugar of Sauternes would give it a lower freezing point.
For those with colder passive cellars, how much do you worry about low humidity in the winter? I assume it gets pretty dry in those temps. Do you run a humidifier, or not worry about it?
Once again, the Gold book has all the answers. Per his suggestion, I have a large tub of water in my passive cellar. I have an old towel that has one end in the tub, and one end on the concrete floor. That seems to do the trick for me.
Humidity ranged from 73% - 78% this January (and temps between 55-56 F, despite most days below 32F, and many days at or below 0F).
The coldest part of my below grade, passive, massively insulated Minneapolis cellar is down to (wait I’ll go check right now) 48. The warmest right now is 50. I did not expect that it would be as even as that. I built the cellar when we moved to MN 20 years ago and as you’d expect this is the coldest it’s been. The warmest it’s been is 68.
No worries here. Very happy with passive.
This may be a dumb question, but I’ll risk it to satisfy my curiosity. Shouldn’t the temperature variability of a passive cellar be heavily linked to whether it is sealed/insulated vs the rest of the basement? So it would in the former generally mirror the floor temperature which should be more stable and in the latter vary a bit more in extreme weather?
That should be basically right. I’d just add that ceiling insulation is probably the most important because the upstairs is likely to be warmer than even a finished basement.
Gold talks about this in his book as well. It’s interesting because most general construction folks are adamant that you shouldn’t insulate your basement ceiling to avoid mold & mildew issues. I’m under the impression you definitely don’t want to put a vapor barrier on the ceiling like you do the walls. Although, I’ve seen it recommended. Anyone put a vapor barrier in the ceiling of a passive or non-passive cellar?
That would make sense in the absence of a cellar, because basements tend to be cooler (heat rises) and damper (some infiltration of moisture). A barrier to having that moisture escape could create a recipe for mold.
However, with a wine cellar one wants a vapor barrier on all sides (other than floor, assuming ambient temp is below cellar temp) because it is cooler, and the humidity of the house that doesn’t condense on warm surfaces could condense on the outside walls/insulation of the cellar otherwise (including the ceiling or floor above).