Development and testing of thermochromic coatings for buildings and urban structures

• Published in: Solar energy 2009-04, Vol.83 (4), p.538-551
• Main Authors: Karlessi, T., Santamouris, M., Apostolakis, K., Synnefa, A., Livada, I.
• Format: Article
• Language: English
• Subjects: Applied sciences; Buildings; Comparative analysis; Cool paints; Energy; Exact sciences and technology; Experiments; Miscellaneous; Natural energy; Organic leuco dye mixture; Protective coatings; Solar energy; Thermochromic coatings; Urban heat island; Urban microclimate
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2008.10.005

The present study reports the development and comparative testing of thermochromic coating to be used in buildings and urban structures. Experimental results from an extensive comparative analysis of the thermal and physical behaviour of thermochromic, highly reflective (cool), and common coatings are reported and analyzed. The surface temperature was monitored on 24 h basis from August to mid-September 2007. It was revealing that the temperature of thermochromic coatings was lower than cool and common coatings. Measurements of spectral reflectance indicated that the thermochromic coatings at the colored phase (below the transition temperature of 30 °C) are energy-absorbing while at the colorless phase (above the transition temperature of 30 °C) are energy-reflecting. The data obtained was used for the calculation of solar reflectance. The results showed that the solar reflectance of the thermochromic samples was significally higher compared to the cool and common ones. A 10-day period test was also performed showing the impact of solar radiation on thermochromism. The comparative results demonstrate that the use of thermochromic coatings can both contribute to energy savings in buildings, providing a thermally comfortable indoor environment, while can contribute highly to improve the urban microclimate.