How can I get the asphalt r-table?

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@Wild We need some more information. Are you asking for the insulative R-value of asphalt as a material layer? Or is this something else? What simulation tool are you using?

I need an asphalt r-table to calculate the average luminance. I am developing an Excel spreadsheet for luminotechnical simulations, but a critical point is the r-table ... when I compare the results obtained with other software, the difference is significant precisely because we use different tables from the others.

@Wild what 'other software' are you comparing your Excel spreadsheet results to? A quick internet search turned up this presentation about an R-table used for a road lighting simulation in Radiance.