Wine Cellar Innovations Blog

Wine 101: Passive Wine Cellars or Underground Wine Cellar

January 5th, 2011

Passive wine cellars, or an underground wine cellar, use ground temperature to moderate the temperature swings and make the temperature swings seasonal instead of daily. Whereas refrigerated wine cellars can go anywhere in your house, a passive wine cellar must be located in a subterranean basement.

Annual Temperature Can Fluctuate

The graph above charts ground temperature variation over a year by depth below ground level. This chart is for a temperate climate and can vary if you go north to a colder climate or South to a warmer climate.

I picked two ground depths for discussion 7’-6” for an average basement ceiling height in an older home and 9’-6” for an average height in upscale newer homes. The funnel which looks like a champagne glass is the high and low temperature of the soil at a given depth. The closer you get to the surface the temperature of the soil swings broadly from summer to winter with a mean of 56 degrees. At 7’-6” which is represented by the first horizontal line the soil temperature varies from a low in the winter of 48 degrees and a high during the summer of 64 degrees with a mean of 56 degrees. At 9’-6” the temperature seasonal swing is 51 – 61 degrees. 55 to 56 degrees is considered the ideal wine cellar temperature. Why mostly because of the convention. The European wine cellars of the famous wineries in Europe store their wines in deep caves, which are frequently stone quarries from Roman times. These caves are usually 20’ deep or more. At that depth, they stay at the mean temperature of 56 degrees plus or minus less than one degree over the year.

A passive wine cellar in a home can never achieve the tight temperature range of the deep caves but it can make the swings moderate and seasonal. At 7’-6” the temperature swing is 16 degrees from 48 -64 and at 9’-6” the swing is 10 degrees 51-61. Without going into the why, which is the subject of another blog, the lower the temperature that wine is stored at the slower it ages. Temperature swings if significant, 14 degrees or more, cause your wine to breathe through the cork which increases the aging process significantly. If the temperature swing is seasonal the damage is much less then if it is daily by a factor of 365 days.

To create a passive cellar, or in-ground wine cellar, in your home basement, you allow the cool temperature from the floor to enter while you block out the higher temperature from the house and higher ground levels on the exterior walls.  The diagram above shows a passive wine cellar construction detail. By using a vapor barrier and high R-value insulation, you block temperature exterior to the wine cellar and allow the ground temperature from the floor to enter. In this case, the exterior concrete basement wall was insulated on the outside but it can also be insulated from the inside. To this, you need to add an exterior grade door with a full 360-degree weather seal around it to have the best underground wine storage.

Window of Optimal Drinkability

Higher temperatures and significant temperature swings accelerate the aging process which is not necessarily a bad thing if done on a controlled basis like a passive cellar. It just means your wines are ready to drink earlier. Where this does make a difference in maintaining your wine in the optimal drinking range once they have peaked.  Many whites and some reds are at their peak when bottled. Some reds take years to age to their peak. Once at their peak you want to keep them there to enjoy as long as possible. The proper wine cellar environment is the key. A refrigerated wine cellar gives you total control but a passive cellar, or basement wine storage, is the next best thing.

Contact us to speak with one of our expert Design Specialists to figure out how you can let your wines properly age.

13 responses to “Wine 101: Passive Wine Cellars or Underground Wine Cellar”

  1. Mike Arndt writes:

    Would like to discuss passive storage construction with one of your design specialists.


  2. Knute writes:

    Read this book:

    How and Why to Build a Wine Cellar
    Richard M. Gold

    I did, and my cellar came out great.

  3. SSP writes:

    So, if I have a basement wine room which is actually bumped out from the main wall so that three of the sides of the wine cellar are exterior poured concrete walls, can I just insulate and barrier the ceiling? The fourth side of the “box” will be frameless glass and there will not be any vent in the wine cellar.

  4. JLD writes:

    You have a great situation for a passive cellar. As you said, you need insulation and vapor barrier on the wall that is not below grade and ceiling. In addition you will improve your passive cellar condition by insulating 30-36″ below grade on the other three walls. That is frost line in the temperate zones and the ground above that point will fluctuate during the seasons. In addition you want to put a vapor barrier down to the floor on those three exterior walls. You can get moisture that penetrates through the concrete even if you don’t see water. For the same reason is would be wise to seal the concrete floor with a good paint or concrete sealer with tile or other covering on top.

  5. SSP writes:

    Thank you for the information. I wonder if by using a vapor barrier even on the three exterior walls it might end up with lower than ideal humidity? The rest of the basement is being finished and will be climate controlled although the temperature is generally so pleasant that neither heat nor AC will be used very often. The back part of the basement where the cellar will be located also does not have any windows. We are going to seal the concrete and use a decorative stain. What is the insulation of choice. I will definitely have them insulate down a few feet from the top. Although, even there, the exterior is a patio (which is why there is no window cut out) which has a cement slab then dry laid limestone so it takes a lot to get through to the poured walls. The house was built in 2009 so I’m sure that the exterior walls have some sort of coating on them (as I recall it looks like black tar?) that must be the water barrier. Thanks again for the help.

  6. JLD writes:

    Those exterior walls would not have to be sealed on the inside if they are sealed on the outside. If you have a good vapor barrier on the interior wall and ceiling and the door has a good gasket seal, then the cellar is going retain any humidity that comes from the outside walls or floor if they are unsealed. Being a new home and treated the way you describe that probably is not a concern. High humidity is a good thing as long as it doesn’t go past a point. I keep my wine cellar at 75% relative humidity. 80% or higher can start to create mold and mildew conditions. The higher humidity keeps the corks swollen and keep the wine from wanting to wick out over time.

  7. The Best Place for Home Wine Cellars? Under Your Feet! | writes:

    […] easier, more economical option is to build a passive wine cellar. And the only place to put a passive wine cellar is in the […]

  8. James MacEachern writes:

    I have a similiar situation as SSP. I have a exterior concrete room in my basement. All walls are concrete including the ceiling and floor. I am thinking I need to seal all of the concrete and insulate the ceiling and down 30-36″ on the walls. What do you recommend for insulation, the ceiling is low so I want to maintain as much height as possible. Could I get away with 2×4’s with spray foam? If I only come down 30-36″ inches do I leave the lower concrete portion exposed? Not sure how it will work with the racking. Lastly I was thinking of using wood look LVT on the floor to match the rest of the basement but would it be better to have just decorative concrete? Sorry for all the questions.

  9. Kristi writes:

    Hi James,
    Not a problem with the questions but the best place to get answers is filling out our contact form or calling and speaking to us directly. These comments can be hidden in SPAM sometimes, I do apologize 🙂

  10. Ron writes:

    Hi Do you need to vent a passive cellar

  11. Al LaCroix writes:

    Thank you for the article and comments. I have a few questions and I’ll share my experience. Like Ron, I wonder if I would benefit from a vent? I have a passive cellar set up under the stairs to my basement. This area is 5 x 9 feet, on the north side of the basement with two cement walls. It was not designed to be a wine cellar, I simply moved out shelves used for miscellaneous storage and set up a tall Open Diamond Cube and a 10 column waterfall rack. The waterfall closely matches the slope of the ceiling under the stairs. I have insulated the ceiling and walls facing the rest of the basement. I did not insulate the top part of the cement walls and I’m questioning if my ceiling is sufficiently insulated. Does anyone have thoughts to share?

    I built a temperature / humidity detector with a WiFi connection to our home network. I monitor T & H, sending readings to a server based database every five seconds. I keep a browser tab with graphs (temp & rel humid) of the last seven days. Daily temperature fluctuations are typically less than one degree F. This time of year, humidity ranges from 42 to 50%. Is that too low? If yes, what remedial action should I take?

  12. Kristi writes:

    Hi guys! I know we replied to you offline but wanted to respond in a comment here. Installing a vent will cause temperature fluctuations. As for as insulating the top of the walls and ceilings, more is always better!

    Once you are installing a humidifier, it wouldn’t really be a passive cellar at that point. While we recommend maintaining a RH of 50% of higher, you may be better off getting the temperature down to 55 degrees.

    Keep us posted and good luck!

  13. Michael Scott writes:

    Insulation is the key. The outside ground temperature will drop markedly inside when going 20″ down. The water table must be considered as well as run off. A good moisture barrier and insulation will slow down the process, but you must consider all aspects in the building process. Ventilation must be done through an underground system that has a filtering process from the ground level that calls for several hundred feet to absorb heat and moisture much like a destillery going through an evaporation process. Temperature goal of 55 is set however depending on location 58-62 degrees is usually met in a passive moderate design.

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