Global Radiative Sky Cooling Potential Adjusted for Population Density and Cooling Demand

Abstract

Thanks to recent advances in nanophotonics and scalable manufacturing of metamaterials, radiative sky cooling has emerged as a “self-reliant” cooling technology with various potential applications. However, not every region across the globe is well suited for the adoption of radiative cooling technologies, depending on the local climate, population density, cooling demand, air conditioning saturation, economic prosperity, etc. Because the atmospheric downward longwave radiation, especially the portion from the atmospheric window (8–13 µm), is substantially affected by weather conditions, the performance of a well-designed radiative cooler can be vastly different across regions and seasons. Here, we first map the global radiative sky cooling potential in the form of net cooling power density. We then further evaluate it based on the global population density and cooling demand. In terms of the adjusted potential, we show that geographically and demographically “transitional” regions, located between wet and dry climates as well as sparsely and densely populated regions, are better suited for the adoption of radiative cooling technologies because of their temperate climate and moderate population density. Even in densely populated and humid regions, the cumulative impact and other accompanying benefits must not be ignored.

An Emerging Energy Technology: Self‐Uninterrupted Electricity Power Harvesting from the Sun and Cold Space

“…Figure 1a,b gives the global distribution of annual mean solar irradiance and net radiative cooling power. [21][22][23] Low-latitude and high-altitude areas have higher solar radiation, which is more conducive to harvesting energy from the sun. In addition to heat radiation from the sun, objects (such as solar absorber) on Earth can also absorb sunlight and convert it into heat; thus, keeping the Earth warm.…”

“…Reproduced with permission. [21,22] Copyright 2021, The authors, published byMDPI. c-e) The thermodynamics limits of harvesting energy from the sun and outer space.…”

Investigation of the Energy-Saving Potential of Buildings with Radiative Roofs and Low-E Windows in China

“…For heat transfer in the cloud, the cloud is usually simplified as a black body. Thus, the downwelling radiation from the cloud can be expressed by [27]:…”

A Scalable Microstructure Photonic Coating Fabricated by Roll-to-Roll “Defects” for Daytime Subambient Passive Radiative Cooling

“…The measurement system depicted in Figure a–c consisted of a Peltier device, a PID controller, a data acquisition (DAQ) system, a power supply, a thermopile pyranometer, and a device for measuring the sample temperature. The theoretical calculations were conducted based on the model proposed by Aili . For these calculations, temperature and humidity data were obtained from field test measurements, the heat transfer coefficient was estimated as 10 W/(m 2 K), and the cloud cover rate 0.125 was cited from National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service (NWC)–Chicago O’Hare International Airport weather record .…”

“…The theoretical calculations were conducted based on the model proposed by Aili. 34 For these calculations, temperature and humidity data were obtained from field test measurements, the heat transfer coefficient was estimated as 10 S18. The deviation between the field test and theoretical calculation may be attributed to factors such as the estimated cloud cover rate and parasitic heat loss (heat convection and conduction) from the test platform.…”