New solar thermal technology can transform ordinary windows into solar-powered heaters that can increase window temperatures by nearly 15 degrees F. in cold weather, according to a new study published in the journal Nano Letters.
The new surfaces utilize tiny plasmonic nanoantennas made of nickel-aluminum oxide that are patterned onto glass as an array. The antennas absorb light, which then heats the entire surface, potentially offsetting how much additional heating is needed. The antennas absorb sunlight much more efficiently than the bare substrate and are transparent, colorless to the naked eye and capable of preserving nearly the entire color spectrum of sunlight.
Cold windows significantly impact building heating requirements because anyone sitting near them radiates their body heat toward the cold window, which then necessitates a higher indoor temperature to maintain comfort, explains the research team, led by Alexandre Dmitriev of the University of Gothenburg. A warmer window won’t act as a heat sink, so FMs may be able to turn down the artificial heating by a few degrees, potentially saving money.
The research team now aims to achieve even larger temperature increases by enabling the nanoantennas to absorb UV and near-infrared radiation, which make up a large portion of solar radiation.