Research on Thermochromic and PCM Doped Infrared Reflective Coatings

The present research investigates the development of thermochromic and PCM doped infrared reflective coatings and the potential of their application on urban structures in energy savings and improvement of the microclimate.

Thermochromic coatings were developed by using thermochromic pigments into an appropriate binder system. The color-changing temperature was 30°C. The same binder system was used for the production of highly reflective (cool) and common coatings, in order to investigate and compare the thermal and optical characteristics of colormatched thermochromic, cool and common coatings. The results demonstrated that during the experimental period, surface temperatures of thermochromic samples were lower than the temperatures of color-matched cool and common. Issues concerning the photodegradationof thermochromic coatings are also discussed.

The performance of organic PCMs used as latent heat storage materials, when they are incorporated in building coatings is also studied. Comparative testing proved that all PCM doped infrared reflective coatings present lower surface temperatures than cool and common coatings of the same color. Studying the daily temperature differences it was noticed that peak temperature differences occur between PCM and common or cool coatings from 7am-10am.These peak temperature differences are not noticed for common and cool coatings. Moreover investigating the temperature gradient it was shown that for this time period the values for the PCM coatings is much lower compared to cool and common. Coatings containing PCMs store heat in a latent form maintaining constant surface temperatures and discharge with a time delay.

Keywords: Phase change materials, thermochromic pigments, optical and thermal properties.