This data is not used in simulations when the Data type is 2-Spectral but is still displayed as it gives a spectral-average overview of the solar transmission and reflectance.
For uncoated glass, when alternative optical properties are available—such as thickness, solar index of refraction, and solar extinction coefficient—they can be converted to equivalent solar transmittance and reflectance values using the equations given in Glass Optical Properties Conversion.
The solar transmittance for the pane at normal incidence averaged over the solar spectrum.
The inside (back-side) and outside (front-side) solar reflectance properties of the pane at normal incidence averaged over the solar spectrum.
Note, For uncoated glass, when alternative optical properties (thickness, solar index of refraction, and solar extinction coefficient) are available, they can be converted to equivalent solar transmittance and reflectance values using the equations given in 'Conversion from Alternative Specification of Glass Optical Properties' in the EnergyPlus documentation).