New solar radiation transmittance models of transparent envelope based on spectral splitting and their influence on building heat gain

Abstract

Climate change and the energy crisis have led to increasing attention to building energy efficiency worldwide, and transparent envelopes are more critical as a weak link in building energy efficiency. However, there is a lack of quantitative research on the spectral transmittance properties of transparent envelopes. In this paper, the spectral transmittance of transparent envelopes is quantitatively studied using the controlled variable method. The transmittance calculation formula in the existing standard is modified. Firstly, five types of transparent envelopes commonly used are selected, and their transmittance to the full solar spectrum is studied to establish a transmittance model for different wavelengths. The study also focuses on the 300 nm–1100nm waveband and establishes a solar radiation transmittance benchmark model (SRTB model) based on single-pane clear glass. Secondly, the solar radiation transmittance at different wavelengths is tested by considering both the glass material and the inclination angle, and a solar radiation transmittance modified model (SRTM model) that can be modified to the SRTB model is established. Thirdly, the variation between the incident angle and transmittance is investigated, and the solar radiation transmittance-incident angle model (SRT - IA model) is developed. The results show that deviations between the fixed transmittance and SRT - IA model can reach a maximum of more than 10% for incident angles of less than 60°. Finally, the variation in radiation heat gain due to the SRT - IA model and fixed transmittance is compared in China based on typical meteorological year data. The research conclusion can provide a more precise assessment of the building heat gain from transparent envelopes and then evaluate the building energy consumption reasonably, and provide a theoretical basis for the full-spectrum utilization efficiency of solar radiation.