Radiative cooling technology utilizes the atmospheric transparency window (8–13 μm) to passively dissipate heat from Earth into outer space (3 K). This technology has attracted broad interests from both fundamental sciences and real world applications, ranging from passive building cooling, renewable energy harvesting and passive refrigeration in arid regions. However, the temperature reduction experimentally demonstrated, thus far, has been relatively modest. Here we theoretically show that ultra-large temperature reduction for as much as 60 °C from ambient is achievable by using a selective thermal emitter and by eliminating parasitic thermal load, and experimentally demonstrate a temperature reduction that far exceeds previous works. In a populous area at sea level, we have achieved an average temperature reduction of 37 °C from the ambient air temperature through a 24-h day–night cycle, with a maximal reduction of 42 °C that occurs when the experimental set-up enclosing the emitter is exposed to peak solar irradiance.

Significance: The coldness of the universe is an enormous but strikingly underexploited thermodynamic resource. Its direct utilization on Earth therefore represents an important frontier for renewable energy research. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic either from operational or aesthetic considerations, but the resulting heating by sunlight is undesirable. Here we experimentally demonstrate a thermal photonic scheme that can cool these structures by thermal radiation to outer space, while preserving the structures’ solar absorption. Our work shows, for the first time to our knowledge, that radiative cooling can be used in combination with the utilization of sunlight, and opens new possibilities for using the coldness of the universe to improve the performance of terrestrial energy systems.

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