Why isn't this replacing aircon over the whole world? Unless that IR-transparent window is made of gold dust, it has to work out cheaper than the energy cost of running an air conditioner.
If my napkin math is right, solar panels give around 2x higher electricity production per square meter than these devices give cooling power. Then that goes into a COP of ~3 for your aircon, and the solar panels have have a factor of 6x better cooling performance per area covered.
Then factor in that electricity can be used for lots of other useful things than cooling, and that solar power variation during the day is perfectly matched with cooling demand, it's a no brainer.
Adding to everyone else, but local climate makes a big difference. This isn't very useful unless you have dry still air, and it works best at night, but could maybe work during the day if you have a good view of the sky but have blocked the sun.
Most places with dry still air don't need specific cooling at night, because "everything" already cools due to this effect, and it doesn't stay hot for long after the sun goes down. Areas that need a lot of cooling overnight tend to be humid, which disrupts radiative cooling. Also, it doesn't take much airflow for convection to transfer more heat than radiation, and most places have variable wind... so you can't really count on it.
> Most places with dry still air don't need specific cooling at night, because "everything" already cools due to this effect, and it doesn't stay hot for long after the sun goes down.
Exactly this. This is reflected as well in the article, even if not promintently: they have 30C Celsius at midday (which is hot) and 4-5C at night (which is cold). 25C between day and night is close to desert behavior as far as diurnal air temperature variation [1] is concerned.
my air conditioner is rejecting 3000 watts to the outdoors right now, even though my bedroom is the same temperature as the nighttime outdoors. doing that with radiative cooling would require 8 square meters of emitter area at 400 watts per square meter and a clear, low-humidity sky (not necessarily night, but in the daytime, you additionally have to keep the sun off the panels). my air conditioner's condenser is significantly less than 1 square meter as seen from the sky and also works when it's cloudy or humid outside
basically forced-air convection heat transfer is a motherfucking miracle, and vapor-compression refrigeration even more so
Then factor in that electricity can be used for lots of other useful things than cooling, and that solar power variation during the day is perfectly matched with cooling demand, it's a no brainer.