A spectrally-resolved method for evaluating the solar effect on user thermal comfort in the near-window zone

Abstract The effects of solar radiation play an important role in human thermal comfort. When predicting the shortwave solar thermal effect through windows on indoor occupants, the spectra of solar irradiance, window transmittance, and skin absorptance must be considered. This work proposes a spectrally-resolved method for predicting this effect on occupants facing windows in the near-window zone. The vertical and horizontal penetration of direct solar irradiance is also characterized. In this work, we quantify the differences in resultant thermal comfort estimations between the spectrally-resolved and conventional constant-value methods through a series of simulated conditions on different days of the year and at different times of day, as well as with various window orientations and sky conditions. Through numerical analysis, we investigate the effects of and interactions among the various parameters and demonstrate situations in which the spectrally-resolved method is necessary. By understanding the necessity of the spectrally-resolved method and the influence of variations in spectral and energy intensities, we are able to make preliminary judgments regarding when the spectrally-resolved method is essential to making relatively accurate predictions of indoor thermal comfort in the near-window zone. This research provides a new and fundamental numerical method that can be used to take the spectral characteristics of solar energy, windows, and human skin into account for more accurate user thermal comfort analyses in the near-window zone.