Evaluation of Solar Heat Gain Coefficient and Transmittance, Reflectance & Emittance Measurement of Flat Glass by UV-Visible/NIR Spectroscopy

Download PDF September 14, 2017

Introduction

Solar Heat Gain
V-670 UV-Visible/NIR Spectrophotometer

Heat shield glass is typically made from eco-friendly materials that help in the prevention of global warming and reduction in energy costs. Testing methods for the evaluation of heat shield glass is stipulated by JIS R3016 and require visible transmittance, visible reflectance, solar transmittance, solar reflectance, and emittance measurements. From these measurements, the solar heat gain coefficient can be calculated, which is defined as the fraction of incident solar radiation admitted through a window.

This application note shows how to obtain and evaluate transmittance/reflectance spectra of a flat glasses using an integrating sphere and calculate the solar radiation absorbance using the Solar Transmittance/Reflectance Visible Light Transmittance/Reflectance program.

Experimental

Measurement Conditions
Measurement Range2500-300nmData Pitch0.5 nm
UV/Vis Bandwidth5.0 nmNIR Bandwidth25.0 nm
Scan Speed400 nm/minResponseFast

Keywords

V-670, UV-Visible/NIR, ISN-723 Integrating sphere, VWST-774 Solar Transmittance/Reflectance Visible Light Transmittance/Reflectance program, solar heat gain

Results

Spectra of both heat shield glass and conventional glass were measured and are shown in Figure 1.

Figure 1. Transmittance (left) and reflectance (right) spectra of heat shield glass (green) and conventional glass (blue).

The solar radiation results of the heat shield and conventional glass were calculated using the Solar Transmittance/Reflectance Visible Light Transmittance/Reflectance program and are shown in Figure 2 and Table 1.

Figure 2. Solar Transmittance/Reflectance Visible Light Transmittance/Reflectance program.
Heat Shield Glass %Conventional Glass %
Solar Radiation Transmittance41.8986.10
Solar Radiation Reflectance31.857.82
Solar Radiation Absorbance26.266.08
Visible Light Transmittance76.3889.95
Visible Light Reflectance8.808.52

About the Author

Satoko Suzuki is a senior manager of the molecular spectroscopy applications laboratory at the JASCO facility in Hachioji Japan.