Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

web.stanford.edu

Post reply on HN
Print view View original

1–10 of 68 posts

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#3

Post by _Microft »

MauranKilom wrote: post #2

Very cool concept! Has any product come out of this in the 7 years since it was published?

I know of no products but the area of research seems to be active and the article I linked to is getting cited frequently:

https://scholar.google.de/scholar?as_ylo=2021&hl=de&as_sdt=2...

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#4

Post by leoedin »

To compare to an air conditioner. This device has about 40W of cooling per m2.

Apparently in Australia you should size between 80 and 120 W/m2 of air conditioning (I think this is cooling watts rather than power usage watts) - https://www.google.com/amp/s/www.crownpower.com.au/blog/choo...

So that means every square meter of living space needs 2 square meters of radiative cooling (assuming no other passive cooling infrastructure). I suspect you'd see further inefficiencies getting the heat to the passive cooler.

So it's within the same order of magnitude of an ac, but not powerful enough that it would be straightforward to retrofit.

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#5

Post by varjag »

leoedin wrote: post #4

To compare to an air conditioner. This device has about 40W of cooling per m2. Apparently in Australia you should size between 80 and 120 W/m2 of air conditioning (I think this is cooling watts rather than power usage watts) - https://www.google.com/amp/s/www.crownpower.com.au/blog/choo... So that means every square meter of living space needs 2 square meters of radiative cooling (assuming no other passive cooling in…

There's a lot of potential applications outside of habitat AC in Australia.

For example cooling down stand-alone hardware in the field.

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#7

Post by kumarvvr »

leoedin wrote: post #4

To compare to an air conditioner. This device has about 40W of cooling per m2. Apparently in Australia you should size between 80 and 120 W/m2 of air conditioning (I think this is cooling watts rather than power usage watts) - https://www.google.com/amp/s/www.crownpower.com.au/blog/choo... So that means every square meter of living space needs 2 square meters of radiative cooling (assuming no other passive cooling in…

A typical AC cycles its power input. Its not constantly On. One benifit of using this system could be to continuously remove heat from the house and then use an AC on top of it.

There is always a consumption value to free beer.

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#8

Post by the8472 »

leoedin wrote: post #4

To compare to an air conditioner. This device has about 40W of cooling per m2. Apparently in Australia you should size between 80 and 120 W/m2 of air conditioning (I think this is cooling watts rather than power usage watts) - https://www.google.com/amp/s/www.crownpower.com.au/blog/choo... So that means every square meter of living space needs 2 square meters of radiative cooling (assuming no other passive cooling in…

The technology has advanced since then, now white paints with high emissivity in the infrared window are being researched. So if you cover the entire building with that you would get some free, always-on cooling that way.

Re: Passive radiative cooling below ambient airtemperature under direct sun (2014) [pdf]

#9

Post by sandworm101 »

kumarvvr wrote: post #7
leoedin wrote: post #4

To compare to an air conditioner. This device has about 40W of cooling per m2. Apparently in Australia you should size between 80 and 120 W/m2 of air conditioning (I think this is cooling watts rather than power usage watts) - https://www.google.com/amp/s/www.crownpower.com.au/blog/choo... So that means every square meter of living space needs 2 square meters of radiative cooling (assuming no other passive cooling in…

A typical AC cycles its power input. Its not constantly On. One benifit of using this system could be to continuously remove heat from the house and then use an AC on top of it. There is always a consumption value to free beer.

>> A typical AC cycles its power input.

If it has reached the requested temperature. Like basically all consumer thermostats, it is a bang-bang controller. There is no set on-off cycle. If the AC unit is running at capacity, ie it is properly sized for requirements, it will just be on all the time.

Post reply on HN