The Influence of NIR Pigments on Coil Coatings’ Thermal Behaviors

Abstract

The effect of over-heating in urban areas, called the urban heat island effect (UHI effect), is responsible for greater energy consumption for cooling buildings. Several reflective near-infrared (NIR) coatings, called cool coatings have proved to be effective for contrasting the UHI effect. The thermal and appearance properties of cool coatings depend on the color and they often have been studied only at the initial state, without undergoing atmospheric degradation and soiling. In this work, the thermal, visual and durability behaviors of red and brown polyester-based organic coatings for roof applications were studied. All samples were subjected to accelerated degradation cycles composed of UV-B and salt spray chamber exposure. The sample degradation was assessed by infrared spectroscopy, gloss and colorimetric analyses. Moreover, the thermal behavior was studied by means of a simplified experimental setup. Finally, a soiling and weathering test was conducted to simulate the soiling of three years’ external exposure. Despite the phenomena of chemical degradation and a decrease in aesthetic properties, the samples maintain their thermal performance, which is not even influenced by dirt products. In addition, NIR pigments significantly improve the thermal behavior of brown coatings.

Esthetic performance of thermochromic pigments in cataphoretic and sprayed coatings for outdoor applications

“…The esthetic performances of the coatings were also assessed by means of UV‐B exposure. This procedure is usually employed in the characterization of organic coatings with long outdoor service life 62–65 . Figure 6 shows the total color variation, ΔE, during 500 h of UV‐B light exposure.…”

“…This procedure is usually employed in the characterization of organic coatings with long outdoor service life. [62][63][64][65] Figure 6 shows the total color variation, ΔE, during 500 h of UV-B light exposure.…”

Use of Remote Sensing in Comprehending the Influence of Urban Landscape’s Composition and Configuration on Land Surface Temperature at Neighbourhood Scale

“…However, our albedo analysis, i.e., higher albedo values over the industrial subcategories to the residential ones, might be one of the potential explanations. Note that high albedo or the low absorption of incident sunlight was probably attributed to having rooftops with coated steels or metal sheets over the industrial neighbourhoods [47][48][49]. On the other hand, the rooftops/shingles in the residential neighbourhoods would be mainly made of asphalt with dark colour, so they might absorb more sunlight [49][50][51].…”

Colored Paints Containing NIR-Reflective Pigments Exposed to Accelerated Ultraviolet Radiation Aging with Possible Application as Roof Coatings

“…The innovative aspect of this work is the development of a very easy and economical lab-scale method for assessing variation of thermal efficiency and esthetical parameters of cool coatings as a function of exposure to artificial UV-B radiation. A previous study [25,26] aimed to assess the potential of this simple methodology as a reliable alternative to the most used tests [10][11][12][13]19,20,23].…”

“…As a comparison, the cost of a reflectometer is higher than 60,000 euros. In a previous work [25], a simulacrum with a flat roof was used to make the experimental data collection easier. However, a simulacrum with the painted panels placed at a certain angle more realistically simulates the roof of most buildings.…”