This has actual cooling capacity. From the publication:
"A 72-hour continuous measurement of the ambient temperature and the surface temperature of an 8-in-diameter hybrid metamaterial under direct thermal testing. A feedback-controlled electric heater keeps the difference between ambient and metamaterial surface temperatures less than 0.2°C over the consecutive three days. The heating power generated by the electric heater offsets the radiative cooling power from the hybrid metamaterial. When the metamaterial has the same temperature as the ambient air, the electric heating power precisely measures the radiative cooling power of the metamaterial. The continuous measurement of radiative cooling power over three days shows an average cooling power > 110 W/m2 and a noon-time cooling power of 93 W/m2 between 11am – 2pm. The average nighttime cooling power is higher than that of the daytime, and the cooling power peaks after sunrise and before sunset. The measurement error of the radiative cooling power is well within 10 W/m2 (32)."
Fans won't drop temperatures below ambient. This will.
Comments
Making the absolute best it can do the equiviemnt of a fan on the roof which can't replace AC.
You are right it won't replace the AC, but the technology could lead to a reduction in overall AC use.
This has actual cooling capacity. From the publication:
"A 72-hour continuous measurement of the ambient temperature and the surface temperature of an 8-in-diameter hybrid metamaterial under direct thermal testing. A feedback-controlled electric heater keeps the difference between ambient and metamaterial surface temperatures less than 0.2°C over the consecutive three days. The heating power generated by the electric heater offsets the radiative cooling power from the hybrid metamaterial. When the metamaterial has the same temperature as the ambient air, the electric heating power precisely measures the radiative cooling power of the metamaterial. The continuous measurement of radiative cooling power over three days shows an average cooling power > 110 W/m2 and a noon-time cooling power of 93 W/m2 between 11am – 2pm. The average nighttime cooling power is higher than that of the daytime, and the cooling power peaks after sunrise and before sunset. The measurement error of the radiative cooling power is well within 10 W/m2 (32)."
Fans won't drop temperatures below ambient. This will.
If you covered things like parking lots and sidewalks, it would reduce the heat island effect and hence air temperature, and so reduce AC some more.
The same reason why cities plant so many trees. https://www.epa.gov/heat-islands/using-trees-and-vegetation-...
Only as much as some tarps over a building and a fan 'cooling' the AC's evaporator coils.
Don't get me wrong it's a neat effect, just not particularly useful.