Accurately Quantifying Radiative Cooling Potentials: A Temperature-correction to the Transmittance-based approximation

TL;DR

This paper identifies a significant underestimation in radiative cooling potential calculations caused by the transmittance-based approximation and proposes a temperature correction method to improve accuracy while maintaining simplicity.

Contribution

It introduces a temperature correction to the transmittance-based approximation, accounting for heat loss to the upper atmosphere, thus reducing estimation errors in radiative cooling potential calculations.

Findings

The transmittance-based approximation underestimates cooling potential by over 10%.

The proposed temperature correction significantly improves the accuracy of cooling potential estimates.

The correction retains the simplicity of the original model while enhancing precision.

Abstract

Theoretical calculations of the cooling potential of radiative cooling materials are crucial for determining their cooling capability under different meteorological conditions and evaluating their performance. To enable these calculations, accurate models of long-wave infrared downwelling atmospheric irradiance are needed, However, the transmittance-based cosine approximation, which is widely used to determine radiative cooling potentials, does not account for the cooling potential arising from heat loss to the colder reaches of the atmosphere itself. Here, we show that use of the approximation can lead to > 10% underestimation of the cooling potential relative to MODTRAN 6 outputs. We propose a temperature correction to the transmittance-based approximation which accounts for heat loss to the cold upper atmosphere, and significantly reduces this underestimation, while retaining the advantages of the original model. In light of the widespread and continued use of the transmittance-based model, our results highlight an important source of potential errors and a means to correct for them.