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Solar Absorption Index (SAI) as a Parameter to Assess the Coolness of Fabrics Exposed to Sunlight

Research and development


  • Scipioni Marco
    Queens University of Charlotte and Lumia Group LLC, Charlotte, USA
  • Silva Edmir A.
    Disruptive Technologies, UNIFI Manufacturing Inc., Greensboro, USA
  • Farahi Faramarz
    Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, USA

Nr DOI: 10.5604/01.3001.0014.2383

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Any textiles intended for outdoor usage, particularly in a hot climate with intense sunlight, must be designed and engineered to provide cooling comfort to the wearer. In the case of apparel, clothing creates a microclimate that helps the body maintain its regular thermoregulatory and physiological activities while offering protection against outdoor exposure to UV rays. It is well known that fabrics that absorb significant amounts of solar radiation become inherently hot and feel uncomfortable. This article presents a review of the fundamental radiation interaction mechanisms of fabrics and discusses the key role that fabric structure plays in fabric radiation absorption to determine how cool or hot a fabric will become when exposed to sunlight. A new parameter called the Solar Absorption Index (SAI) is introduced and can be used to characterise the level of coolness (or hotness) of a fabric exposed to solar radiation. The SAI is calculated directly from the fabric’s temperature, ultimately the main factor in determining fabric ability to stay cool. The discussion presented in this article focuses solely on the interaction between solar radiation and fabrics without considering the effects of convection, conduction or any interdependency with the moisture level in the environment.


textiles, clothing, coolness, sunlight, fabric structure.


Scipioni M, Silva E, Farahi F. Solar Absorption Index (SAI) as a Parameter to Assess the Coolness of Fabrics Exposed to Sunlight. FIBRES & TEXTILES in Eastern Europe  2020; 28, 5(143): 44-49. DOI: 10.5604/01.3001.0014.2383

Published in issue no 5 (143) / 2020, pages 44–49.


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