Visual metering of the urban radiative environment through 4π imagery

Abstract

In urban climate or thermal comfort, radiative exchanges are often expressed in terms of Mean Radiant Temperature. Considering that a single temperature does not properly represent the radiative environment, an alternative method is proposed here to observe it in depth. This method is giving an alternative for evaluating the urban radiant environment through a measurement that covers a solid angle of 4π steradians.The results are validated by comparison with those obtained by the black-globe method. The difference is always less than two degrees.This paper proposes the joint use of photographic and LWIR thermal cameras for a radiometric study. Due to the nature of its approach, this method allows for spectral discrimination, in two bands: 380–780 nm and 7.5–13 μm. This encourages the separate analysis of each part of the spectrum as well as the ensemble.Furthermore, the small duration of each measurement opens up the possibility of studying the radiative environment free from disturbances due to the inertia of the measuring device.