Green Building Forum - Measuring the temperature under my solid floor

Measuring the temperature under my solid floor

tony — Tue, 28 Apr 2009 13:40:00 +0100

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thermocouple from a specialist supplier and a "data logger" will do it.

Measuring the temperature under my solid floor

mike7 — Tue, 28 Apr 2009 17:10:00 +0100

Posted By: wookey
Loading it in Openoffice, it is largely full of err:523 'does not converge', which appears to be due to the recursive definition in M3 =(M3+1)*O3
(03 is 1). I'm not sure what spreadsheets do with this sort of recursive function? Maybe I need to tell it to recurse harder?

That M3+1 is just my iteration counter. Set O3 to zero, iterate once or twice, and the counter resets. Then O3 to 1 again. I don't know about OpenOffice (or anything else much to do with computers - this is almost my starting point) but maybe it is similar to excel where you have to tell it you want it to iterate, otherwise you get a load of warnings that 'there is a circular reference in the formula'. - and the iteration depends entirely on these.

Posted By: wookey

Shouldn't the bottom row, which is the deep soil temp, come from $I$23 rather than just being '10'?

Well spotted. Actually I meant it to be $G$23, ie. copied and pasted from the G 'builders yard' column. Same result as plain 10 though. I'm impressed you could get this far in ten minutes. A lot more headscratching and pencil sucking would happen here.

The happy absence of macros is because at the time I didn't know what they were, but I do now. I use one to prevent the screen updating every iteration, which slows things down a lot. Another to make the chart. Hope this won't be a problem.

Measuring the temperature under my solid floor

tony — Sat, 25 Jul 2009 21:46:03 +0100

Thinking about my new house http://www.tonyshouse.info/ if the temperature under the basement floor is going to try to rise to the average temperature of the basement rooms then any help I can give to that process by feeding in surplus solar energy should reduce my heating needs. Yes?

Measuring the temperature under my solid floor

bot de paille — Sat, 25 Jul 2009 22:11:35 +0100

I think the answer has to be yes.

The thing to do would be to have your basement as an indoor swimming pool, hammam. Then circulate the water through solar panels in the roof. benefit from the thermal mass etc etc

I saw a programme the other day about female self builders here in France. One woman had done an incredible job refurbing an old farm house by herself over 10 years, room by room. She did an amazing job.

The crowning piece was a candle stick on the wall which when pulled caused the entire fire place to lift up reveiling steps down to a hammam in the basement. The hammam was stunning and done entirely by the woman.
Sounds a bit naff but it looked amazing, as if she had employed experts and paid a fortune.

Measuring the temperature under my solid floor

DdraigGoch — Sun, 26 Jul 2009 15:41:44 +0100

Now THAT's a house conversion I'd like to see!

I'm new on here, and very much an info noob on such matters, so, in advance, please accept my apologies for the idiocies I shall undoubtedly post; the tea stains on your monitors are down to you!

I'm about to get the builders in - a dreadful prospect - to update and improve wherever we can afford it. I'm working on a set of barns which were converted to 1990 house standards, now woefully inadequate. Guess who forgot to get Building Regs agreement when the Planning Permission was obtained 8 years ago ....

Hence my interest in this topic as I have nearly 1500 sq ft of concrete slabbed flooring and I don't think there's any insulation beneath it. The floor is never warm, but then again, it's never painfully cold either. The area is 5.5m x 19m in one direction then 6mx15m in an L off the end of it. I wondered if such a large area as this would be a useful subject for discussion. I'll get my coat now, shall I?

Measuring the temperature under my solid floor

mike7 — Sat, 01 Aug 2009 12:02:48 +0100

Posted By: tonyThinking about my new house http://www.tonyshouse.info/ if the temperature under the basement floor is going to try to rise to the average temperature of the basement rooms then any help I can give to that process by feeding in surplus solar energy should reduce my heating needs. Yes?

Any news on how it's going, Tony? Do you have any means of measuring the amount of heat you're tucking away?

Measuring the temperature under my solid floor

spoonandfork — Thu, 06 Aug 2009 01:05:05 +0100

Tony, I take it all those temp readings were taken before you had the thermal stores working?

And any tips on buying thermocouples and setting them up? I'd also like to get things that measure damp, to see if my planned insulation work does the job. When I put perimeter insulation in round a slab in an old building I didn't dare dig that deep, ie the 700 -1000 mm that's been mentioned.

Measuring the temperature under my solid floor

tony — Wed, 12 Aug 2009 21:22:18 +0100

s&f -- temperatures were measured under my existing house -- sorry for confusion.

Search on web for thermocouples and data monitors, damp (humidity) measuring devices are a bit more expensive and physical sampling and weighing, drying and weighing again might prove more economical?

Measuring the temperature under my solid floor

tony — Thu, 27 Aug 2009 18:49:25 +0100

Just started to hook up thermocouples in my new house --- 1 m down under basement floor 17 C

this is mid way between my thermal dump bore holes also seen 15 and 13 down there -- nope to get some better info once it is all running properly.

Measuring the temperature under my solid floor

James Norton — Thu, 27 Aug 2009 19:16:15 +0100

Keep up the good work...
J

Measuring the temperature under my solid floor

tony — Sat, 28 Nov 2009 18:12:16 +0000

A meter down under the middle of the floor of my new house it was 16 C all of October and it has dropped to 15.7 now at the end of November.

Measuring the temperature under my solid floor

Mike George — Sat, 28 Nov 2009 18:15:04 +0000

Heat loss to the outside or into the basement do you think? Has the basement air temperature ever dropped below 15.7 ?

Measuring the temperature under my solid floor

tony — Sat, 28 Nov 2009 20:29:41 +0000

not yet

Measuring the temperature under my solid floor

brig001 — Tue, 08 Dec 2009 09:04:23 +0000

Hi Tony, has temperature under your basement dropped because of the recent heavy rain? The reason I ask is that I noticed our solid floor is cooler at one side of the house than the other by about 2 degrees C, and the only reason I can see is that the house is built on a hill with the cold side cut into the ground and the warm side being built up. The ground on the cold side is permanently wet at the moment and I suspect that water is flowing under the slab.

Thanks, Bri.

Measuring the temperature under my solid floor

tony — Tue, 08 Dec 2009 09:14:33 +0000

I dont have any water at all under my slab but it has gone back up to 16C now anyway!

there was some research done on the effects of heat movement in wet soil which shows that it is little different from dry, but if you have moving water then it could be a problem as it will transport heat away.

Measuring the temperature under my solid floor

brig001 — Tue, 08 Dec 2009 11:04:11 +0000

Thanks Tony. I know I have moving water in front and behind the house, so I think I must have it under the house too. I have no idea how to prove it and what to do about it though...

Measuring the temperature under my solid floor

tony — Mon, 04 Jan 2010 08:38:39 +0000

New house 1m down under the middle of my slab has now fallen to 15 C -- round the edge it is a bit cooler

I hoping that next year it will only fall from say 19 to 18 from Oct to Dec ?

Measuring the temperature under my solid floor

mike7 — Mon, 04 Jan 2010 12:22:52 +0000

Had a look at my old simulations - sounds plausible, but... we don't know how much heat you've been able to put down there this last year, how much in 2010, or what air temp you have at basement floor level.

Measuring the temperature under my solid floor

mike7 — Mon, 04 Jan 2010 16:35:25 +0000

Tony - I suppose there must be a cool layer of air just above your basement floor. If we knew the temperature gradient across that layer,we could work out the heat flow into the floor, and work back from that to estimate the soil conductivity below....?

Measuring the temperature under my solid floor

gyrogear — Sun, 16 Aug 2020 22:01:09 +0100

Resurrecting ancient thread FWIW.

I have been logging soil temp for over 3 yrs, at irregular & spontaneous periods, out of interest. Total of 64 datapoints. Have tried to graph them to best of my ability...

I have one sensor, one meter below the crawlspace floor, so 2.8 meters below natural ground level.

OBSERVATIONS:
Soil temp basically oscillates between 14Â°C in January and 17Â°C in August.
However, cold temperatures are trending up, and hot temperatures trending down.
Latter phenomenon seems to have been halted this year, with serious solar input.
Notwithstandng, it looks like the usual inversion is about to occur within next week or so...

Main Events:
. Fitted new (airtight/insulated) garage door June 2017.
. April to October 2019Â : intermittent (chaotic...!) crawlspace heating trials using solar air.
. August 2019Â : added DG patio doors to garage (which is main heat source at present).
. March 2020Â : increased duct area and beefed up the load fans - began serious daily loading.
. Planning on integrating slate-hung facade as transpired solar collector ASAP

gg

Measuring the temperature under my solid floor

tony — Mon, 17 Aug 2020 08:29:35 +0100

Although you are measuring soil under slab, this is more of a reflection of the temperatures in your crawl space which will follow that.

Looks like nighttime cooling might be a good move in the summer by adding fans and closable vents

Measuring the temperature under my solid floor

gyrogear — Mon, 17 Aug 2020 09:39:48 +0100

Posted By: tonythis is more of a reflection of the temperatures in your crawl space

Cheers, Tony, I was hoping that that was the case !

What I also hope is that the inverse will eventually occur - viz. the soil temp will start affecting the CS temp!
In the sense that it gives UP heat rather than taking it away...

Posted By: tonyLooks like nighttime cooling might be a good move in the summer by adding fans and closable vents

Agreed - it's the CS that saves us in Summer -- it keeps our bedroom down to a livable temp, which was 23Â°C last week, while upstairs was over 26Â°C...

In winter, upstairs (living area) generally manages all day without any heating, and just a quick log-burn at night. However,the basement hangs around at 17Â°C and drains the house, that's why I want a warmer crawlspace !

gg