Fine summer weather [image credit: BBC]
A rooftop installation is needed, but low running costs are claimed.
Engineers from two American universities developed a kind of natural air conditioner with almost no consumption of electricity, reports Xinhuanet News.
The study published on Friday in the journal Joule described the innovative water-cooling system capable of providing continuous day-and-night radiative cooling for structures.
The low-cost hybrid organic-inorganic cooling material is scaled into a roughly 13-square-meter array, small enough to fit on most rooftops, according to the study.
The advance could increase the efficiency of power generation plants in summer and lead to more efficient, environmentally-friendly temperature control for homes, businesses, utilities and industries.
“You could place these panels on the roof of a single-family home and satisfy its cooling requirements,” said Zhao Dongliang, the paper’s lead author and a postdoctoral researcher in Colorado University Boulder’s Department of Mechanical Engineering.
“As Earth’s temperature warms due to the absorbed heat from the sunlight during the day, it continuously emits infrared light to the cold universe all the time,” said Professor Yang Ronggui at Colorado Boulder and lead author of the study. “During the night, Earth cools down due to the emission without the sunshine.”
The film-like material reflects almost all incoming sunlight while still allowing an object’s stored heat to escape as much as possible, keeping it cooler than ambient air even in the midday sun.
It can be produced at low cost using the current roll-to-roll manufacturing techniques, according to the researchers.
Continued here.
Graphical Abstract
Tallbloke's Talkshop 
[the link to the rest of the story didn’t work, DNS resolver failed]
[mod] works on Chrome, link is: http://www.xinhuanet.com/english/2018-10/27/c_137561127.htm
I wonder how this would work in winter.
I would imagine exactly the same way, ie prevent the house warming by Solar energy.
So great for a place hot all year round.
Can you take it off for the winter?
Sounds like an evaporative cooling system, since they mention water with a reflector? How does it compare with a foil reflector?
It is not uncommon for the ambient air temperature where I live to be 35-40C. Insulation and some sort of reflective surface will keep my house from heating above ambient, but how will this system reduce the internal temperature to 28-34C? And 34C seems a bit warm, especially when we are in the 70% humidity range.
Seems that this wonder is missing some basic thermo. I’ll stick to my heat pump and use some electricity. When I lived in Michigan a whole house fan would do well most of the time. Not in central Virginia. And when I lived in New Orleans with humidity approaching under water, this would never have worked.
Very slim on actual details and heavy on marketing hype.
They are supposed to have built a prototype, if so why no pictures and where are the experimental details like, outside temperature measured every few minutes with corresponding inside temperature.
I know that cold air falls but how do they get that cold air from the roof of a building into every room of said building, little things engineers like to know.
At the moment this sounds like another pie in the sky idea looking for fools to shower it with money. Sorry, but there are just too many things that appear to work in lab conditions but never scale up to real world production.
Subambient Cooling of Water: Toward Real-World Applications of Daytime Radiative Cooling
Highlights
• 10.6°C subambient cooling of water around noon under direct sunlight
• Subambient cool-water production at various constant temperatures
• The effect of weather conditions on the performance of radiative sky cooling
• kW-scale radiative sky cooling system to demonstrate scalability of the technology
– – –
A bit more blurb here (see Summary): https://www.sciencedirect.com/science/article/pii/S2542435118304689
‘Graphical abstract’ added to the blog post.
Climate change: Low cost, low energy cooling system shows promise
By Matt McGrath
Environment correspondent
26 October 2018
https://www.bbc.co.uk/news/science-environment-45991225
Same principle we all use to keep cool. We sit in the shade and sweat with a glass of beer to hand. The only difference being that we don’t recycle the beer.
Getting your house to sweat could be a bit costly if you wish to compete with a standard air conditioner. Otherwise this is just a research grant lobby ploy.
Apparently the film is highly reflective to all light frequencies, preventing radiation from warming the substrate( likely water for its heat capacity). Since it is a sunny day, the film, which is mostly transparent to infrared, allows the substrate to radiate directly into space.
Good trick that. On a cloudy day it might not work very well, if at all.
So let me get this straight…
It radiates in the IR, cooling to space. That same IR that the global warming folks tell us is blocked by CO2… yet it works…
It must be like the albedo effect…
Needless to say, the albedo effect is one of the most complicated factors in climate science
https://www.universetoday.com/39937/albedo-effect/
“I would imagine exactly the same way, ie prevent the house warming by Solar energy. So great for a place hot all year round. Can you take it off for the winter?”
The solar effect is much smaller in winter than summer, particularly at high latitudes. Much like having a light colored roof, the net effect is dominated by the summer months.
Air con feedback conundrum…
But there’s an inconvenient truth: you can only make it cooler inside by making it warmer outside.
A study in Phoenix, Arizona, found the hot air pumped out of air conditioning units increased the city’s night-time temperature by 2C.
Of course, that makes air conditioning units work harder, making the outside hotter still.
https://www.bbc.co.uk/news/business-39735802
– – –
How Air Con changed the World!
In 1950, fewer than 500,000 people lived on the southern coast of the Persian Gulf. Today, it is home to 20 million. In Saudi Arabia, 70% of electricity is used for air conditioning.
. . .
Air con has its critics but, as The Economist remarked, it uses far less energy than heating – “the necessity of which is seldom contested”.
https://www.airconco.com/news/air-con-changed-the-world/