Cellar sweepstake

[uncle tom]

On March 19th I checked the temperature of my new cellar - it was 9.5C with no variation between floor and ceiling.

In three months time I will measure the temperature again.

Guess the temperature at:

a) 4" below the ceiling
b) 4" off the floor

Thermometer reads in 0.5C increments.

- A bottle of The Port Society's finest unfiltered reserve will await the person with the closest guesses.

Relevant data:

Annual average air temperature: 9.5C
Mean winter air temperature: 3.5C
Mean summer air temperature: 15.5C
Height of cellar, floor to ceiling: 7'3"
Depth below original soil surface of cellar floor: 6'
Average mounding depth, including roof slab: 3'

[Glenn E.]

The start of summer isn't typically as warm as the end of summer, but it is certainly warmer than the start of spring. Being underground stablizes the temperature swings, but I'm going to guess that there will be a little bit of a rise by June.

Floor: 9.5 C
Ceiling: 10 C

[g-man]

at 6' below surface and only 1'3" above the surface and such mild avg summer temps
I'd be surprise to see any difference at all

Floor: 9.5 C
Ceiling:9.5 C

[Alex Bridgeman]

My guess has already been taken

So I will guess 10C and 10C

Alex

[benread]

I think you have described a cellar that is covered in earth and therefore exposed to the elements above to some degree. If we got a normal amount of rain, would the evapouration above help the cooling below? If that is correct, and we are forecast to have a drier than usual spring, would that indicate the temperature increasing more than normal in the cellar below?

I actually have no idea, but it sounds plausible! So:

top:12.5C
bottom: 12C

[PhilW]

My guess would be 10.5C and 10.5C...

[g-man]

My guess has already been taken

So I will guess 10C and 10C

Alex

snooze you lsoe

[g-man]

Actually if we're really being sticklers

I'd like to ask uncle tom to provide the Time of measurement and in 3 months what would be the time he would take the temperature readings.

[uncle tom]

I'd like to ask uncle tom to provide the Time of measurement and in 3 months what would be the time he would take the temperature readings

If I've got a measurable intra-day temperature fluctuation, I've got a problem!

IIRC, my opening measurements were taken around lunchtime, and in the interests of science, I will endeavour to do the same again..

[g-man]

Might I also ask if you were walking a long distance before heading into the cellar ?

As you didn't specify the size of the cellar, human body temperature could potentially add to a change in temperature if you were say, moving cases in after walking on a hot day after lunch before finally reading the temperature.

[uncle tom]

The human body generates an average of 100W of heat, or 100J/s

Energy needed to raise 50 tons of brick and concrete by 1C = 50MJ

Therefore time needed for my body heat to raise cellar temperature by 1C (ignoring conduction into the surrounding soil..) = 500,000 seconds, or about a week!

Taking the free air alone, the energy needed to raise temperature by 1C is only about 25KJ, so this could quite quickly be changed by my presence, the heat from the lights, or indeed a draught induced as a result of opening the door.

However, the thermometers I am using have the sensor imbedded in a plastic casing that makes them relatively insensitive to sudden air temperature fluctuations. When first installed, they took about 20 minutes to give a steady reading.

I will of course take readings upon entry, rather than exit..

[g-man]

Now I am impressed and would love to see pictures of this cellar!!

[uncle tom]

Bit late reporting back on this...

I've just downloaded the datalogger readings, and this shows absolutely no day/night fluctuation, although with readings consistently in the mid nineties, humidity levels are a minor concern.

The datalogger tells me that on 19th June, the mid room temperature was 12.5C, and the digital thermometers are now showing a ceiling/floor differential of 2C. The ceiling thermometer is now up to 14.5C.

So Ben looks to be the lucky winner of the bottle!

I'm also drawing the tentative conclusion that as a rough rule of thumb, it probably takes about a metre of soil to create a 1C deflection from seasonal averages, so if your local climate has an average annual temperature of 10C, with a summer average of 15C and a winter average of 5C, you need a depth of 5m to achieve effective temperature stability.

[benread]

Nice to win something for a change, although with the very wet Spring and Summer we have had, my theory is blown out of the ground so to speak!