Washington: 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.
Ancient Egyptian pigment can boost energy efficiency
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.
Though white is the most conventional and effective choice for keeping a building cool by reflecting sunlight and reducing energy use for air conditioning, building owners often require non-white colours for aesthetic reasons. For example, bright-white asphalt shingles are almost never used on sloping residential roofs.
Researchers have already shown that fluorescent ruby red pigments can be an effective alternative to white; this insight on Egyptian blue adds to the menu of cooling colour choices. They also found that fluorescent green and black colours can be produced with yellow and orange co-pigments.