Passive Air Conditioning

[old man emu]

As I wa having my shower today (at my sister's place cause my bathroom is not finished) I was cooling off with the refreshing cold water.  That water comes from the bore tank about 100 metres away from the house. An idea struck me. Would it be possible to make an air-conditioning system that makes use of the constant subsoil temperature environment.

 

This is what I envisage:

1. Use the ripper blade on the tractor to rip a field of trenches about 900mm deep in an area outside the house, similar to an evaporation bed for the sewage.

2. Lay a continuous line of polypipe in the trenches, with the ends coming together near a wall of the house. Close up the trenches.

3. Fill the polypipe with water. 

4. Connect the polypipe to a radiator from a large car or truck. Fill the radiator with water so that it and the polypipe are full. 

5. Install a small 12V water pump and attach a 12V fan to the radiator.

6. Somehow install some ducting to direct air from the radiator into the house.

7. Use a trickle charger solar panel to power the 12V fan and pump.

 

At 900 mm the subsoil temperature should be pretty constant, and well below the 30+C outside air temperature.

[Jerry_Atrick]

Not quite passive, but ground source heat pumps can be used for cooling, too..

 

Sadly, for us, such a technology is not viable.

 

https://jaga.co.uk/blog/how-to-cool-your-space-with-a-heat-pump

 

[onetrack]

Subsoil temperature is around 15° constantly, but you need to be pretty deep to get that constant temperature, probably at least a metre.

I see no reason why your system wouldn't work - but the volume of water in the pipes is also an important factor - more volume = slower resistance to temperature changes.

 

Then again - you could always pick up a shovel and dig a cellar!   They're a nice spot to be, on hot days! - plus, it's a great area to store all your wine!

[spacesailor]

A lot of ' upper class ' English houses have cellars to keep meat as well as wine cool .

Also , there's a grate outside on the front of the house for ' coal delivery ' .

No use being cooled in an English winter . LoL.

spacesailor ,

[old man emu]

My niece has a system that is simply a buried pipeline that is open at both ends. I don't know what creates the air movement, but it seems to keep the house cool.

 

1 hour ago, Jerry_Atrick said:

ground source heat pumps

The system I'm thinking of is meant to be cheap to create. That's why I was looking at a 12V system to work a pump to circulate the water and to power the radiator fan. Electric radiator fan in cars work off 12V.

 

1 hour ago, onetrack said:

but the volume of water in the pipes is also an important factor - more volume = slower resistance to temperature changes.

I agree that this would not be a way of instantaneously generating cool air. It would take some time for the water in the pipeline to reach equilibrium with the soil temperature, let's say a month from installation. However, once equilibrium was reached the resultant water flow through the radiator would keep the incoming air at a constant temperature all year round, so the system would be good for cooling in summer and warming in winter.

[nomadpete]

All the reports that I have read regarding simple subsoil air cooling hace failed. Such things as burying a matrix of pvc downpipes a metre under the slab of the house - failed.

 

However, the Australian experience with ground sourced heat pumps has been dramatically successful. Summer Power reductions of 30% - 50% have been reported. But it is ridiculously expensive due to lack of competition in the industry.

[onetrack]

Pete, what were the reasons given for the subsoil air-cooling failures? I'd imagine the circulation speed of the water would be a critical factor. Maybe it simply requires a large volume of water? 

The brother and I bought a 5 acre property in a wheatbelt town in W.A. in the early 1970's. It was an old Goldfields house that had been transported there in 1923. The owner was an old Italian bloke.

Because he was obviously short of a dollar and couldn't afford a water tank, he'd excavated a big underground water tank, lined it with a thin layer of concrete to seal it, and roofed it.

The tank was about 8M in diameter and about 1.5M deep. The water in that tank was always a nice cool 15°, regardless of outside temperature.

When we moved in, reticulated mains water had become available, so we connected to the main, and the big underground tank became obsolete - so we ripped the roof off it, tiled it with cheap mosaic tiles, and turned it into a swimming pool!

 

Edited February 18 by onetrack

[facthunter]

It's the only way to heat or cool. I installed it for the hot water and cut my electricity bill in half.  Nev

[facthunter]

In hot an DRY use an evaporative set up but it will use fair bit of water. The lower parts of a fairly deep dam will stay cool.  Nev

[onetrack]

We've got natural gas for our hot water, because I hate cold showers when the power goes off!!  It costs us about $1.50 a day for endless hot water, via a continuous-flow HWS, and I'm happy enough to pay that!

[old man emu]

18 minutes ago, onetrack said:

The owner was an old Italian bloke.

 he'd excavated a big underground water tank, lined it with a thin layer of concrete to seal it, and roofed it.

Them Eyties were always really good with their concreting. Been doing it since Pontius was a pilot.

[onetrack]

Anytime you want-a da concrete shoos, Luigi is your man!!

[facthunter]

Cement shoes .. ALL sizes.   Nev

[old man emu]

Here's the secret of Roman concrete

 

 

[onetrack]

One of the secrets to Roman concrete strength and durability - especially when it came to being submerged or frequently sprayed with sea water, was the pozzolanic volcanic ash used as aggregate in their concrete mixes.

 

The pozzolanic ash contained a mineral known as phillipsite, and this mineral reacted with the lime and seawater to form aluminous tobermorite crystals, and these crystals have incredible durability.

 

Modern Portland cement concrete is rapidly degraded upon contact with seawater, and Portland cement concrete in builddings and bridges starts its degradation process after only 50 or 60 years - but the Roman concrete is still intact and unworn after 2000 years.

 

https://en.wikipedia.org/wiki/Roman_concrete#:~:text=In Rome%2C readily available tuff,water than modern-day concrete.

[spacesailor]

The very first " concrete " boat is in a Italian pond .

spacesailor

[facthunter]

Probably another "Bottom of the Harbour" scheme.? Nev

[old man emu]

9 minutes ago, spacesailor said:

The very first " concrete " boat is in a Italian pond .

spacesailor

Had the plans upside down.

[facthunter]

"Pooling" their resources helped the company's Liquidity. Nev.

[nomadpete]

4 hours ago, onetrack said:

Pete, what were the reasons given for the subsoil air-cooling failures? I'd imagine the circulation speed of the water would be a critical factor. Maybe it simply requires a large volume of water? 

 

The ones I read about were simply air systems. Basically large amounts of buried air ducting with a fan to draw outside air through. The plan was to dissipate heat into the subsoil along the way, and discharge cooler air into the home. It did slightly reduce the air temp but not enough to be worthwhile. I would think that using a liquid system would not gather much different 'coolness'.

 

But using that 12 -14 degree cool water as a starting point for an air conditioner (instead of 30 deg ambient air) is a different story. Ground sourced heat pumps are common in Canada and Europe because they are so efficient.

[onetrack]

Ahhh! - but air is a totally different kettle of fish when it comes to heat and cold retention and loss. The reason large bodies of water affect local climate is all due to their slow release of heat, and taking a long time to warm up.

[onetrack]

I just remembered - the old Alice Springs Hospital (now Adelaide House), designed by John Flynn, had a very effective "Coolgardie safe" style of air-conditioning built into its design.

 

The building had a cellar and large underfloor passageways, with a large vent on the roof of the building. Air was drawn through the cellar and then upwards through the building, exiting the roof via the large vent (utilising the "heat rises", and venturi principles). I believe that wetted hessian was also placed in the airways under the building, and in the cellar.

 

The result was a simple but very effective air-conditioning arrangement, that was probably close to todays evaporative coolers in effectiveness. I do recall many of the old hospital patients leaving remarks on how comfortable the hospital was on hot days.

The design also incorporated the wide verandahs that were a feature of all the early buildings, which aided greatly in keeping the direct hot sunlight off the walls, thus reducing heating of the building.

 

A couple of wind-driven exhausters/ventilators on the roof would probably have greatly aided the air flow, too - but they possibly weren't available in that era.

 

I thought that there were also troughs of water under the hospital too, to aid in cooling, but I can't see or find them mentioned anywhere.

 

https://collections.slsa.sa.gov.au/resource/B+61843

 

In the photos on the website below, there's one photo showing a cutaway model of how Flynns air-conditioning system for the hospital worked.

 

https://activatealice.nt.gov.au/eat-drink-shop/adelaide-house-museum

 

Edited February 18 by onetrack

[pmccarthy]

There is a public building in Burke with the same system.

[willedoo]

The Egyptians had water tanks under buildings and ducting to draw air in over the water surface then up through the building to provide cooling.

[nomadpete]

1 hour ago, willedoo said:

The Egyptians had water tanks under buildings and ducting to draw air in over the water surface then up through the building to provide cooling.

It'd work well in their dry desert air.