A color developed by Egyptians thousands of years ago has a modern-day application as well – the pigment can boost energy efficiency by cooling rooftops and walls, and could also enable solar generation of electricity via windows.

Egyptian blue, derived from calcium copper silicate, was routinely used on ancient depictions of gods and royalty. 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 Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has confirmed the pigment’s fluorescence can be 10 times stronger than previously thought.

https://heatisland.lbl.gov/news/article/egyptian-blue-energy-efficiency