The Auswine Forum

Hi all, finally dug the datalogger out of our passive cellar - the hatch has been closed for 14 uninterrupted months. The cellar is 3x4x2.4m, double brick with 100mm concrete-filled cavity. The ceiling is a 180mm concrete slab, at ground level, and forms part of the floor of our free-standing garage. Access is via a 1mx1.2m checker-plate hatch with 100mm insulating polystyrene attached.

A summary:

Daily temp range about 2 degC in summer, < 1 degC in winter. Summer average temp in cellar about 25 degC (peak 27 degC), winter average a bit above 15 degC (hottest summer days were 43 degC a few times, lowest minimum was about 2 degC a few times at the Bureau of Meterorology site a few km away - Perth/Mt Lawley)

Humidity was about 65% to start, rose gradually to around 90% (oops) and stayed there. Unfortunately the cellar had been flooded at a late stage of construction and I think the concrete floor and walls were still holding a fair amount of moisture when we closed the hatch.

Will post a detailed plot when I get home tonight (wouldn't work last night).

Cheers, Dave.

Thanks for the post Dave. Looking forward to the graph. Can you tell us how many bottles you had stored in there. I think this would give us some idea of the thermal mass inside the cellar.

Fortunately only about 12 cartons of wine in the cellar, but a reasonable amount of thermal mass in the form of workshop tools and materials, plastic-wrapped packing boxes full of books and cloth. Total volume I estimate at 10 cubes, total cellar volume is about 30 cubic metres.

The daily max temps at the nearby BOM site are in red, daily minima are in blue, cellar temps are in black (recorded hourly).

Plot attached (I hope)

Dave

Thanks for the excellent info.

Without trying to cause you any grief, 25-27C is way too high an average in summer, IMHO. Your winter temperatures look fine. Your wine will not survive for very long at those higher temperatures.

Great presentation of the data. It would be interesting to plot the middle point between the days high and low. It looks like it would mirror the cellar temperature (not sure what that would mean though???)
I had the same thoughts as dlo. Winter is beautiful but summer is a little to high. Anyone have any thoughts on how you could control it better?
I'm assuming Dave doesn't want to put a cooling unit in seeing the thread has passive in the title.

Ditto - for at least 7 months of the year you're storing your wine way too warm. You'll need to consider a different storage location or active cooling to improve this,

Hey Dave,

Great data,

Im really interested in this as im currently building almost exactly the same thing but i should get lower summer temps as im in Syd.
Just wondering if you insulated the slab from underneath. I know you have the hatch covered but with such a huge thermal mass above i think in the summer months this would still heat up a little, as garages are usually hot boxes, and be hard to get rid of this heat. Also woundering if you are in sand or in clay?

Im pouring a 150mm slab then using foil board (20mm poly and foil backed) hard up against the concrete underside. Then a 50mm Gap more insulation in the way of poly bats 50mm then a suspended gyprock ceiling. The whole system takes up 150mm of ceiling space but i think will be well worth it. Will proberbly test the concrete slab only system first just to see what happens.

Only up to excavation at this stage but thanks for letting me know about the flooding of the cellar I will be sure to keep a tarp over mine untill i get the slab poured and put in a sump just incase.

Red Smurf

It would probably be ok to cellar wine like this for 3-5 years only.

Monghead.

Hi all,

I know, the summer temps are way too high, but at least now I have a benchmark. It would have been useful to have another datalogger in the garage to see what the temperature was doing immediately above the cellar too - lack of foresight on my part.

Now that we're back in the house and the tenants are gone, the wine I had down there is back inside while I figure out a way to keep it cooler. I was thinking of lining the ceiling with extruded PE or similar (like Red Smurf has suggested), and then I am looking at a simple system with a temperature-switched fan to get a bit of cool air circulation to reduce the humidity too.

Red Smurf, the cellar is in sand that has about the texture and stability of sugar, which made the whole project an educational exercise in hole-digging and shoring. Very worthwhile project to do yourself if you have the time and the inclination, but as with everything like that, the second one would be much quicker! The cellar wall thicknesses and so on are based on construction in sand - probably very different requirements for clay, the concrete slab thickness is for a 3m x 4m span that will support a car, and you can park on the cellar hatch too without problems.

In the meantime, looks like I have some drinking to do!

Cheers,

Dave.

Interesting data.

I too have a passive cellar and while it doesn’t get as warm as that here in the Blue Mountains the difference between the summer and winter temperatures is too much if I leave the cellar alone. So I have developed some strategies to handle some of the variation.

Our cellar is basically a room straight off the kitchen so it is easily accessed. In summer if it has been very hot during the day we will leave the house opened overnight and leave the cellar door opened to let some cooler air into the cellar, then close it back up again during the day. In winter I burn a 9 hour T-light candle in the cellar on cold nights. These actions don’t radically change the temperature in the cellar, perhaps adjusting it by half to 1 degree, but I have found it does keep the temperature a lot more stable overall.

It is only summer that is a problem for your cellar. It appears from your data that the overnight low is pretty much always lower than the cellar temp, so if you could get some of that cooler air in overnight it should help. It would reduce the effect of multiple hot days continually building up the temperature.

Hello Dave ,,

Thats a great read and i wanted to ask did you put in any facilities for flooding and did yo consider or look into Passive ventilation ?

When i talk about passive ventilation its when you run air pipes for a few metres before the pipe gets into the cellar say 8 to 10 metres and most is run at he base height of the cellar

Regards Dazza

Hi all,

I didn't put in any facility for drainage - no Council requirement for planning approval, and since the garage floor is a little above the local ground level and the hatch has a lip on it, I figure it will be okay. The flooding happened when there was no roof on the garage and someone (me) didn't cover the formwork. I used a little electric pump to remove the water that did get in, but it didn't have time to dry out properly before we had to pack up and let the tenants move in.

I am considering some ventilation - one option is to run a pipe up to the roof of the garage so it sucks out the damp air (like the vent pipes on drains). Then, some sums over the weekend showed a 90mm diam air duct (PVC pipe) with a decent computer fan at the end will turn over the air in the cellar once every 60 minutes or so. A temperature switch will run the fan when the outside temp is between about 15 and 20 degrees. Hopefully most nights it will run for a few hours. I need to figure out where to run the air intake so it will provide access to cool air, and not be unsightly (the style council - wife - and me have differing opinions on that sort of thing).

Dave