Online SRI calculator

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Online solar reflectance index (SRI) calculator

3 standard wind conditions for SRI calculation
(0-2 m/s)
(2-6 m/s)
(6-10 m/s)
Black surface temperature
Standard black surface: solar reflectance=0.05, emittance=0.90
White surface temperature
Standard white surface: solar reflectance=0.80, emittance=0.90
Sample surface temperature
Your sample surface, with the solar reflectance and emittance input by you below
Solar reflectance index (SRI)
SRI is the sample surface temperate scaled by the standard black and white surface temperatures
Solar reflectance:
The fraction of solar radiation reflected by a surface. 0 (0%) for a perfect black surface and 1 (100%) for a perfect white surface
Solar absorptance:
The fraction of solar radiation absorbed by a surface. Solar absorptance=1 - solar reflectance.
The ability of a surface to exchange thermal radiation with ambient enviroment. The emittance of most surface is between 0.85 and 0.95.
Temperature unit:
The default temperature unit in SRI calculation is Kelvin.

©OTM Solutions Pte Ltd, V1.1.1, 23/06/2020

How to use the SRI calculator?

Simply input your material’s solar reflectance and emittance to the SRI calculator above and get its SRI instantly.

  • Solar reflectance: the range of solar reflectance is 0 – 1, with 0 for perfect black material and 1 for perfect white. If you know your material’s solar reflectance in percentage, simply convert it to decimal (e.g. 56.7% = 0.567).
  • Emittance: it is often called emissivity. The emittance of most materials is between 0.85 and 0.95. If you are not sure, you can simply use the default value 0.90.

The calculator is based on ASTM E1980-11.

What is solar reflectance index (SRI)?

Please refer to the detailed explanation in the SRI testing service page.

Looking for a professional SRI testing lab?

Please visit our SRI testing service page. Our lab is SAC-SINGLAS (ISO 17025) accredited and our customers are from more than 20 countries.

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Comments or feedback?

Please feel free to leave your comments or feedback to this online calculator in the “Leave a Reply” section at the bottom of this page. We will improve this online calculator regularly.

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