Earlier quoted context omitted.
Short answer not really https://what-if.xkcd.com/84/
That's more a "we haven't made enough paint to cover a large fraction of the planet" argument than a "what would the thermal ramifications of such an act be" argument. Which I was excited to read about, but alas.
Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
51–60 of 68 posts
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#52Are there any resources that catalog historical methods of passive cooling? Many of these methods are space efficient but not cost efficient, and many areas of the developing world (where these issues have the greatest impact) have all the space in the world and very limited access to funds.
https://en.wikipedia.org/wiki/Passive_cooling
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#53Earlier quoted context omitted.
Short answer not really https://what-if.xkcd.com/84/
This makes me think: Earth's energy imbalance is around 0.5W/m2, while such a paint sends how much, 40W/m2 through the transparency window? So we'd only have to paint 1/80 of the Earth. That's ~6.4mln km2, or 2/3 the area of the USA. Still a lot, but not impossible. I'm sure paint manufacturing scales better than li-ion batteries, and those more than doubled in production volume over the last decade.
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#54Earlier quoted context omitted.
Short answer not really https://what-if.xkcd.com/84/
That's more a "we haven't made enough paint to cover a large fraction of the planet" argument than a "what would the thermal ramifications of such an act be" argument. Which I was excited to read about, but alas.
https://en.wikipedia.org/wiki/Daisyworld
The argument (and the related Gaia hypothesis) has some important and subtle connections to the facts of climate change. Though even if it's correct, and the biosphere will tend to naturally reassert homeostasis, there's no guarantee we'll enjoy living through it.
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#55I've been actively working on this technology, goal is making it cheaper and simplify installation. Stanford's a highly reflective surface ~95% combined with stacks layers of silica oxide on a wafer under vacume. The trick too achieving bellow ambient temperature is too reflect nearly all solar energy while emitting strongly in the "atmospheric window". Most silica compounds are well suited as emitters, however the h…
wouldn't large scale usage of a device like this essentially increase the planetary albedo and help fight climate change? especially if you just skip the "environmental heat transfer" part
https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf
Basically we need 1W/m^2 of cooling for the earth, so if you could get a radiative cooling device with 100W/m^2 you'd need to cover about 1% of Earth's area
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#56I've been actively working on this technology, goal is making it cheaper and simplify installation. Stanford's a highly reflective surface ~95% combined with stacks layers of silica oxide on a wafer under vacume. The trick too achieving bellow ambient temperature is too reflect nearly all solar energy while emitting strongly in the "atmospheric window". Most silica compounds are well suited as emitters, however the h…
Your work on passive radiative cooling doesn't sound like biotech or related to biotech but your link https://www.scihouse.space is a biotech lab.
I was just wondering the kind of education/knowledge someone who is working on the cooling technology would have, and was surprised to see a biotech background. So am wondering on the journey to get from biotech to whatever is needed for the cooling tech.
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#57I've been actively working on this technology, goal is making it cheaper and simplify installation. Stanford's a highly reflective surface ~95% combined with stacks layers of silica oxide on a wafer under vacume. The trick too achieving bellow ambient temperature is too reflect nearly all solar energy while emitting strongly in the "atmospheric window". Most silica compounds are well suited as emitters, however the h…
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#58Earlier quoted context omitted.
Short answer not really https://what-if.xkcd.com/84/
This makes me think: Earth's energy imbalance is around 0.5W/m2, while such a paint sends how much, 40W/m2 through the transparency window? So we'd only have to paint 1/80 of the Earth. That's ~6.4mln km2, or 2/3 the area of the USA. Still a lot, but not impossible. I'm sure paint manufacturing scales better than li-ion batteries, and those more than doubled in production volume over the last decade.
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#59Earlier quoted context omitted.
Opening the windows at night and running fans to equalize the temperature, then putting space blankets over the windows for the day works wonders on hot days in upstate NY.
One question that I always wonder when hot days strike: Given that I only have one portable fan, what is the best setup at night if it is colder outside than inside: 1. Open the windows and put fan so that it blows air out of one window 2. Open the windows and have fan mix the air inside the room 3. Open the windows and put fan on balcony to blow air from outside in.
I got decent cooling results with two separate window fans, opposite sides of house, one blowing in one blowing out. Of course, all other windows are closed.
Depending on your window frame style, these types of dual fans fit inside a window frame and don't leak air. They can be set to: both in, 1 in 1 out, both out. So quite flexible. https://www.amazon.com/Bionaire-BW2300-N-Reversible-Airflow-...
A single window fan of the above style can cool a single room quite well, blowing cool air in and blowing hot air out.
As others have mentioned, depending on breeze and temperature, opening all the windows can sometimes work better than multiple fans.
Fans are just no substitute for a real AC unit, which can lower indoor air temp to below outside air temp and can also extract moisture from the inside air.
Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]
#60If so, that's pretty sweet.
Like at what scale does this work? How much is needed to cool, say, a 1000 sq ft apartment in nyc?