100 watts of solar heat absorbed by unclothed skin increases the body temperature of the average person by 1 to 2 °C per hour. This effect is positive when winter sun protects against cooling and negative when summer sun puts additional strain on the body. In this context, the influence of clothing on solar heat absorption was investigated as part of an R&D project. For this purpose, knitted and woven structures made of cotton, viscose, polyester and polyamide fibers are being calorimetrically examined. Indanthrene dyes and reactive dyes are varied in terms of color. The results show that the temperature of textiles varies by up to 20 degrees Celsius depending on the construction when solar heat is absorbed. The results can be used in research and teaching and in the design of textiles and clothing.