Quantitative effects of PM concentrations on spectral distribution of global normal irradiance

Abstract

Daylight refers to a free and valuable resource exhibiting photometric and radiometric features, and the physical parameters commonly used to represent its features are irradiance and illuminance. They are both obtained by the spectral power distribution (SPD) of global irradiance, demonstrating that values noticeably affect indoor thermal and luminous environments. Nevertheless, outdoor particulate matter (PM) significantly affects SPD conditions, and two relative spectral notions, i.e., percentage of spectral irradiance (PSIr) and percentage of spectral illuminance (PSIl), were proposed to study the effects of PM10 concentrations in radiometry and photometry with a field measurement, Beijing. As a result, the strong impact of PM10 on PSIr/ PSIl can be noticed in the range (380 to 540 nm) (P-value < 0.01) by correlation analysis, and a wavelength of 510 nm was taken to build models between PM10 and PSIr/ PSIl based on regression analysis. With this wavelength, PSIr varies from 0.29 to 0.25%, and PSIl ranges from 0.48 to 0.42% with the increase of PM10 concentrations from 0.01 to 0.098 mg/m3. With the verification of the model, several bands were further analyzed to comprehensively verify the monotonic correlations, and the band ranging 480 ~ 520 nm were reasonably proved that PSIr/PSIl and PM10 can be well indicated by each other. As influenced by the complexity of spectral transmittance through the glazing, the mutual characterization between solar spectrum and particulate matters can contribute to the building energy-efficient design and develop indoor thermal and luminous environment research in the future.