Passive evaporative cooling has been used for centuries to reduce temperatures. Heat is drawn off as water evaporates, which in turn reduces temperature. The more efficiently this process happens the greater the temperature differential, and that’s exactly what the 3D-printed structure pictured above aims for. Created at the Graz University of Technology in Austria, the cubes noticeably reduce surrounding air temperature thanks to their careful construction. As long as they’re kept wet, anyway.
The key is exposing the maximum amount of water to the maximum amount of airflow, and there are two ways the prototype cooling wall — which is 3D printed from a special clay mixture — does this.
First, the macro design of the 3D-printed blocks maximizes surface area. If the cube in the image above looks familiar, that’s because it’s the gyroid infill pattern. Gyroid is a porous pattern with no “dead ends” or closed sections, and the fact that it 3D prints cleanly with no supports also makes it an ideal structural candidate.
The second advantage is the clay used for the blocks themselves. Firing clay at a low temperature keeps it porous, but this particular mixture goes even further. It’s a bio-inspired formulation of clay, fungal mycelium, and wood chips. After printing, the cubes are fired and the fungus and wood chips burn away, leaving a network of thread-like capillaries with occasional larger pockets throughout.
The result is a porous ceramic cube with a massive evaporative surface area relative to its size. A practical test in a hot attic showed the air near a water-laden cube was nearly 7º C lower, a noticeable difference.
A home experimenter might not have access to fancy mycelium-laced clay mixtures, but it still strikes us as something that could be tried out at home. After all, clever hackers have successfully made DIY versions of passive cooling paint.
optimized version of this technique:
https://www.bbc.com/future/article/20240530-how-ancient-knowledge-of-terracotta-is-cooling-modern-indian-buildings
which is existing since centuries.
OT: this, site, if i allow js but not third-party js (uBlock strict mode), the header picture first loads but then disappears, what’s going on?
Gyroids are far more ‘optimal’ than stacked pipes.
And gyroidal structures were developed by organisms millions of years ago.
/thread
Last two summers it was a desperate fight to save water across most of Europe.
This summer I walked across a major river, which in 2010 had a typical depth of 1,5-2 meters and current so strong you could easily drown. Water level didn’t even reach my knees this time.
Most “classic” water wells (the ones built with concrete rings) in my parent village went dry.
It’s outright scary.
The one counterpoint to the water concern is that cooling electrically is a costly endeavour to say the least. Not that we are suddenly going to see homes built of this stuff but keeping it wet versus water evaporated and moved from watersheds during power generation is likely largely asymmetric insofar as cal/L cooling.
Install solar panels driven air-conditioning. The more sunlight, the more cooling.
Yes i know, except the water used to produce such device :)
Use the solar panel powered air conditioning to condense water, put it on the cubes for extra passive cooling, unless it’s already on the condenser(?) to boost efficiency. Certainly UK summers are hot and humid.
There is a startup in Germany making (fired?) ceramic ceiling tiles that embed a hose like you use for subfloor heating, only they want to do it on the ceiling for cooling.
They designed the system initailly out of something else, found that it condensed water b/c of the temperature gradient, and then decided to use that to their advantage as well, so turned their attention the the material in the tiles.
Like you say, ideally solar panel, driving heat pump in reverse mode, and pushing the cold into the water loop, condensing and using the condensation for extra cooling. I imagine a max cooling before it starts raining inside, though…
Solar powered evaporative cooling very easy and cheap.
I didn’t know you were allowed to end the thread and then write more stuff after that
I wonder if this version of swamp cooler is less maintenance-heavy and cultures less bacteria and fungi than the conventional American version?
I’m guessing that metallic silver powder be wedged into the clay to to help prevent the growth?
because of how porous plastics are I would not put this anywhere near anyone with breathing issues, for that matter i would not really want it near me either. This to me looks like a breeding ground for any and all nasty things.
For around 25-30 years of my life I had nothing but evaporative cooling in the western US. I never really heard of anyone getting sick from it.
I certainly don’t have any history of respiratory illnesses.
Most of that time, I used aspen (wood) pads. I wonder if plastic is significantly different in promoting bacterial, fungal or other undesireable growth?
I had a habit of running maximum bleed off to prevent salt buildup. Maybe that’s a factor?
It’s not like there’s a static, stagnant, water source. Possibly lots of oxygenation given the thousands of CFM of air flowing through the pads. Have never done the math on air flow per square foot of pad.
There’s a lot of evaporation, meaning that the water supply would be refreshed at some interval even without bleed off.
I’ve never run a cooler with anything other than potable water. In the city that water is chlorinated. In the country it was fresh from a well about 50 feet from the cooler. Water quality may be a factor.
Maybe acquired immunity?
I’ve only heard of Legionnaire’s disease in association with refrigeration style air conditioning, not evaporative cooling.
I have to imagine that some university in a dry climate has studied the biological hazard level associated with evaporative cooling.
Interesting…
*plastic as I’ve used, or fired clay as in the article
Some of us have this in our houses without realizing it. There are two styles of whole-home humidifier: steam or evaporative. The evaporative ones use a replaceable “filter” or “pad” which looks almost identical to this. Water drips down the pad and a fan blows through it to add moisture to the air.
They are manufactured in a way that is probably a lot more economical than 3d printing mushroom clay. It’s just a few layers of aluminum mesh, dipped in some powdery ceramic substance.
https://www.sylvane.com/products/honeywell-home-humidifier-pad-agion-coating-hc22e1003
Here’s my skeptical old guy thought: These pads have a useful lifetime of 3-6 months before they get covered in slime, making them unhealthy and ineffective. Exposing a porous surface to water and air makes it the perfect breeding ground for mold, fungus, algae, and bacteria. Even ones that are doped with anti-microbial substances. My prediction is that that once you account for rapid degradation, this will not be a viable cooling strategy.
It might make a difference whether you have a small ‘closed’-loop system (its most extreme form found in those cheap desktop swamp coolers) or a larger system where fresh water is supplied in a continuous fashion. OK those humidifiers and the desktop swamp coolers don’t have a closed loop in the sense that they capture evaporated water to condense and re-evaporate it, but they still have a reservoir that is periodically topped-off meaning you have a ‘lake’ of water that sits there for years.
I bet if they seeded the structure with moss, cooling would be even better (more surface area on the moss, at the expense of increased water consumption).
bro plants actually help retain moisture
bro plants actually help retain moisture..
bro plants can’t absorb an infinite amount of moisture and anything they can’t sits on the surface and is evaporated. Not sure if the idea would work, but the idea is to increase surface area, and moss would do that.
Wait I thought cooling stuff with water was the devil or something
Only viable in dry climates. If the wet bulb temperature is too high it won’t help. Even sweating doesn’t help.
Yeah, south Louisiana is a bit too humid for evaporative cooling. It works, but you’re not going to see the same temp differential that you would in a relatively dry climate.
That said, you can pull the condensate water from your air conditioners to run back over the hot side coils to give them a small boost. Just need to make sure you clean them regularly to prevent buildup.
We should use those to cool data centers. 😏
Evaporative cooling is a standard form of data center cooling. It sometimes uses pads like this one. This is why you heat people getting defensive about data center water use.
I think you whiffed that one
From the Pacific Northwest of the US, this would be a disaster. Even the freeways here grow moss/lichens/other random green things. For drier climates, ancient Persian wind catchers with various enhancements have been used for millenia though they lack the “cool factor” (you saw what I did there) of 3-D printing.
I don’t see a reference to the people who designed it or make it. I have never printed something out of clay. Was hoping to actually look into it further.
Another issue in dry hot climates like the sw usa would be the hard water. Thread-like capillaries would be clogged by mineral deposits pretty quickly.
You can buy demineralized water in vintage auto stores, it’s used for cooling fluid where glycol is forbidden.
bet that gets costly fast
use 45 to 75 gal/day in my swamp cooler…
today 108 outside 78 inside
mineral deposits on the cooling pads clogs the air flow and they need replaced every 4-6 mo
nthes
use a hard water filter like for a mist system.
need to dump water once a day…
Waaaaa so clever ! We are going to miss more and more water during summers and they invent something that need water, a lot of water to cool down a house, yeah ! Research goes on 🤣 brain stopped behind …
We (France) don’t want to store the excess of rain that is ‘lost’ in winter.
What does a structure like this do at night in humid air? Could all that surface area capture moisture from humid air? Or does it hold too much heat for too long? If it does capture moisture, can that water be used the next day?