Air condition is energy consuming, can be hard to maintain in outback areas, and, leaks cooler fluent, that has to be refilled from time to time. Service on compressors can be a hassle, and after all, it sucks a lot out of your day to day economy over the years, especially in countries with tropical climate. In 2017 i Stefan Nyström was in Vietnam, and i noticed how though the nights could be when no cooling is provided. Daytime even more so.
One analogy, is that during the Vietnam war, the dug many miles long tunnels for defense, and managed to defeat the enemy and free their country. However now in peace time, tunnels can provide other benefits, one, is free air condition.
Everywhere on earth surface has a very variation temperature, however, just a few feet under the surface. the conditions is stable, summer and winter, in fact, the deeper you go, the lesser the variation, between peak, hot, and peak cold seasons it is.
In some countries, the underground temperature is provided for areas by graphs, pre surveyed, but for most part, what temperature, at what depth, would be a case by case basis discovery, onsite.
For what i could estimate, for Vietnam, as an example, the depth require to get an efficient amount of temperature difference, delta T, to be able to chill hot inside room air, and lead it back, chilled, and providing free air condition. I use the word free, here:
Of course nothing is free, there is no “free lunch” but in my cost benefit analyze i found that, air condition in Vietnam, was costing the owner 1300 USD yearly in electric bill, to that come the installation and all hardware. Add to that around 1000 USD for the air condition itself, first year. This amounts to 2300 USD
In the example of Vietnam, labor would be cheap, in other areas not, but for all what i find, is that the first year, the cost of production for the underground free AC is covered, this would be done, in 2 years, 3 years, etc, in areas, where it would be very to extreme high expenses, since the big cost is the running cost when you want to have chilled air inside your room.
Its 3 times more expensive energy wise to chill than to heat, and this it was does exactly this to your energy bill. As Vietnam is importing most of its energy, huge savings can be made as totality for the country, aswell as providing for people who could never afford to have air condition to have just that.
The idea is to have a shaft, going 12 meter straight down under ground, this can be done straight under the house, to not invade on neighbors property.
One horizontal shaft is also dug, to provide the cooling. At every 2 meter, a liner of concrete is casted around the tunnel wall, so they will not erode and collapse over time. 2 meter deep hole is dug, then cast, wait for it to settle, dig 2 additional meters, etc.
Its important to not have a major stream of underground water where you want to make this, but it can still be done, and the water stream will boost, your free air condition. To have fairly dry underground properties will make casting easier, and also less draining of the shaft.
For the horizontal shaft, we have to fix into the mold for the wall liner, our measure for cooling air, what i found is that a stainless steel stove pipe liner, would be suitable for this. Loops is fixed in the to tunnel wall, around the tunnel.
Its made to withstand corrosive elements, and while casted into the wall liner, it will be fixed in the tunnel on the inlet side, and on the outlet side, not casted inside the cement, there must be provided insulation, to keep the from earth, chilled air until it can come to the outlet inside the house. 35 foot, 10.6M comes at around 689 USD see example here: https://www.northlineexpress.com/6-diy-chimney-liners.html
Cheapest in Asian part is to import from China, this can be done at this web page: https://www.alibaba.com/product-detail/Flexible-stainless-steel-304-316L-ducting_50019054244.html?spm=a2700.7724838.2017115.28.3c93b095WDi73A
There is cheap insulated flexible plastic ducts on the market, what will be used is depending on location and what is on hand at a particular area.
Notice of importance, there will be condense water filling the stainless ducts over time, this must be drained out, so when installed, a drain hose must be fitted to every loops bottom, otherwise water will hinder the air from circulating freely, aswell as letting microbes have access to water,
not something you would want. Use for this purpose quality hose and pipe fittings, just like this, in brass or high grade plastic, suitable for marine use, do not use iron or or pipe fittings made for indoor use. Treat underground installation just like you would treat an installation underwater, at sea, in salty water, Hose must be marine grade aswell, as clamps would also be.
An inlet duct fan is then used, installed, somewhere in the vertical tunnel, to such hot air from near roof area inside any room in the house. i recommend this placement for noise reducing, other placements is possible if this is of no concern.
Fan comes at 50 USD upwards + shipping, so this is a minor part of the hardware installation: https://www.aliexpress.com/cheap/cheap-inline-duct-fans.html?src=google&albch=search&acnt=479-062-3723&isdl=y&aff_short_key=UneMJZVf&albcp=266121556&albag=7593673036&slnk=&trgt=dsa-42862830006&plac=&crea=64152518476&netw=g&device=c&mtctp=b&memo1=1t2&gclid=CjwKCAjw_8jNBRB-EiwA96Yp1neziJoaFvkfp-w94DZtBLmLK5LdlO2apxrSm159fc5CwQlY2dsyfBoC-cUQAvD_BwE
Also a thermostat which would control when the fan is run is necessary, but not mandatory, Marine bilge pump for small craft would be used to keep the shaft dry always, and runs on 12V, so can be feed directly from solar voltaic sources, if no AC voltage is on site, engine room evacuation fans for boats can be used, as the have high flow rate and runs on 12 volts.
Notice the drain pit at the lowest part of the tunnel.
Investors are needed, contact me for more information, many projects of this type and of greater magnitude is already developed. Lack of funds has stalled my projects.
As of this i release the technology for free, for anyone to use, more details can of course be added to the technologies, but for this i cannot maintain at no cost operation. So if you are prepared to add some funding in the mix many aspects of the development, manufacturing etc can be avoided. Feel free to contact me.
Energy hegemony must end, do your part. Tweet and retweet, spread the message, abundance of cheap air condition here, help it come to fruition.