Chinmaya IAS Academy – Current Affairs Chinmaya IAS Academy – Current Affairs
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A colour developed by Egyptians thousands of years ago can boost energy efficiency by cooling rooftops and walls, and could also enable solar generation of electricity via windows, scientists say. Egyptian blue, derived from calcium copper silicate, was routinely used on ancient depictions of gods and royalty, according to the study published in the Journal of Applied Physics . Previous studies have shown that when Egyptian blue absorbs visible light, it then emits light in the near-infrared range. Now, a team led by researchers at the Lawrence Berkeley National Laboratory (Berkeley Lab) in the US has confirmed the pigment’s fluorescence can be 10 times stronger than previously thought. Measuring the temperature of surfaces coated in Egyptian blue and related compounds while they are exposed to sunlight, researchers found the fluorescent blues can emit nearly 100% as many photons as they absorb. The energy efficiency of the emission process is up to 70% (the infrared photons carry less energy than visible photons). The finding adds to insights about which colours are most effective for cooling rooftops and facades in sunny climates. For example, bright-white asphalt shingles are almost never used on sloping residential roofs.
