Very cool. Evaporative cooling is neat in that it’s low-tech but it is often a bit climatologically awkward. It works great in dry climates, but then where do you get the water? And in humid climates you have the water supply but the cooling effect is greatly diminished. Still, there are certainly some places in the sweet spot where this may make sense
I imagine it would work great where I am in inland California but we couldn’t run it off or rainwater because we don’t get rain from ~ May - November. Still, in years with adequate water supply it’s a cool device.
where do you get the water?
From the rain. They have a built-in reservoir at the bottom, and use a little bit of electricity to pump the water up. And then water is collected back at the bottom etc
Yeah so if you’ve had two months of 35+ days and only a couple mm of rain it does nothing but soak up more heat. Like the above commenter said, there are probably places in a sweet spot for this, but it also wouldn’t work in many places. They even addressed your point about rain directly.
I might be wrong, but I remember seeing some numbers and your toilet would use more water than a similar system, so I still think it might be worth it (unless you use compost toilet with no water, then the comparison goes kaput). Let me try to find the source
Find it?
Anyone please feel free to correct any misconceptions I might have had below, if you have more examples, let me know too:
Keep in mind that stuff like this is expected to vary a lot depending on design, temperatures, solar irradiance, humidity, shapes, water flow, wind speed, wind direction, drag, etc
Based on “Design integration of novel porous ceramic evaporative cooling systems”, their design had a water consumption ranging from 0.4 to 0.8 l/h/m² (liter per hour per square meter of surface area) (whereas predicted data from simulation was around 0.4 to 1.1 l/h)
For comparison, misting systems, which can be a popular technique to improve outdoor comfort in public spaces, might use around 0.8 l/h per misting nozzle
On another study, “Experimental study of cooling effects of a passive evaporative cooling wall constructed of porous ceramics with high water soaking-up ability” DOI, shows an evaporation rate of 20.7 kg/day for an area of 1.1m², converting to l/h/m², it is around 0.784 l/h, where it had max-min air temperatures at 36.4 and 26.2 °C, relative humidity (RH) at 72% and mean wind speed at 0.6 m/s
Another experimental study using porous ceramic water containers measured cooling capacity approaching 225 W/m² of exposed wet ceramic surface under hot and dry conditions (30–35°C air, 35–50% RH).
Computer modelling and experimental investigation of building integrated sub-wet bulb temperature evaporative cooling system DOI
A separate study, from the same author at different conditions, with air temperatures up to 45°C and RH up to 50%, found up to 280 W/m²:
Investigation of an Evaporative Cooler for Buildings in Hot and Dry Climates DOI
Considering latent heat of vaporization of water is about 675 Wh/kg at 30°C, it would give us an evaporation rate of around 0.333 and 0.415 l/h for the previous 2 studies respectively
If we consider that, on average, a healthy adult goes between 4-10 times per day to the toilet and that each time you flush, you can use between 4 to 22 liters of water depending on the efficiency of your toilet… yeah, I think we can agree we might have a bigger problem with water usage somewhere else
Summary of water usage below assuming the system is up 24 hours per day, which was not the case in all above examples
— Liters per 24h Study 1 9.6 - 26.4 Misting nozzle 26.4 26-36 °C / RH 72% 18.9 30-35 °C / RH 35-50% 8 45 °C / RH 50% 10 Water efficient toilet 16 - 40 Old inefficient toilet 88 - 220 So if you haven’t already, and if you can, change your toilet with more efficient option. Bonus points if you get a bidet
TLDR: You are more likely to waste more water going to the toilet than having a passive evaporative cooling wall
Solid effort cheers
An aesthetically pleasing DIY passive swamp cooler is a nice project. There are ways it could be more efficient, but since they’re in Texas and definitely have an A/C, anything to offset their use of it is a positive.
If all our architecture did shit like this with consideration to place, it could even matter.
Looks more like a cool garden feature than something for cooling your house, or is this more to counter the urban heat island while in your garden?
Needs more greenery on it but hopefully that would grow with time.
they mentioned their patio in the video so I think it’s a way to keep things a bit cooler while they are sitting outside
Could be interesting to try something like that, don’t have anything like as much space though. Wonder what kind of water consumption rate to expect. If something useful could be grown in it then that would also be a large benefit.
Wonder what kind of water consumption rate to expect
This is rainwater recycled!
Sure, but you can only store so much rainwater and I haven’t seen rain in almost 2 months. In England! My plants would like some of the rainwater I have stored too and its very limited.
Also got an allotment but for that I just use the hosepipe as I am paying for it in the annual fees anyway and I haven’t yet worked out a realistic rainwater collection option. A regular large water butt would maybe cover watering the whole plot once. An IBC tank could last over a month, but I don’t have a roof to collect much rainwater there in the first place.
Might need to look into more efficient watering, how much do they actually need. Digging trenches or pits and filling them with water and allowing it to soak in overnight seems like a good idea but I don’t know how big or how much water is actually necessary.
The water drips down into the containment area where it’s pumped back up so I believe it is quite cyclical and efficient.
Do you know where the wild things go?
They go along to take your honey
Please don’t go please don’t go
I love you so I love you so
Nice project, feels chill even in video
11 degrees cooler is pretty good for a non-enclosed space without any forced air. Big fan of this technology, my swamp cooler only starts to struggle in 100+ temperatures, the electricity use is next to nothing compared to AC, and it’s a really simple machine to maintain and repair, like this video shows the core mechanism is just a small water pump.
As a decorative water feature with a secondary cooling effect, I can see this working.
But the most efficient cooling method is still solar powered heat exchanger. You could use the water condensation from that to run our swamp cooler.
