The color created by the Egyptians thousands of years ago has found modern applications. Its pigment can dramatically improve energy efficiency by cooling roofs and walls and collecting sunlight through windows.
The blue color obtained by the Egyptians from calcium copper silicate was often used to create images of gods and nobility. Past research has shown that when it absorbs visible light, Egyptian blue emits light in the near infrared range. Today, a team led by researchers from the National Laboratory. Lawrence Berkeley confirmed that the fluorescence of the pigment can be ten times stronger than previously thought. The study is described in the Journal of Applied Physics.
By measuring the temperature of surfaces covered with Egyptian blue and exposed to the sun, the researchers found that fluorescent blue pigments can emit about 100 percent more photons than they absorb. The radiation process is up to 70 percent energy efficient (infrared photons carry less energy than visible photons).
This, in turn, helps to understand which colors are most effective for cooling roofs and facades in warm climates. While white is the most traditional and effective color for keeping buildings cool by reflecting sunlight and reducing energy consumption for air conditioning, building owners often choose other colors for aesthetic reasons. For example, bright white asphalt shingles are almost never used for roofing residential buildings.
The heating temperature of Egyptian blue compared to other colors in the sun.
Researchers from the National Laboratory. Lawrence Berkeley has already shown that fluorescent ruby pigments can be effective substitutes for white. Now the choice is complemented by the Egyptian blue. The scientists also found that fluorescent green and black colors can be produced with yellow and orange complementary pigments.
In addition to cooling potential for buildings, Egyptian blue fluorescence can also be useful for solar energy production. By coating windows with this pigment, photovoltaic cells at their edges can convert near-infrared fluorescent energy into electricity.
Vladimir Guillen
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