New glass coating blocks 90% of sun’s heat

RESEARCHERS at A*STAR Singapore Institute of Manufacturing and Technology have developed a new coating for window glass which blocks almost 90% of infrared heat from the sun.

In warmer climates, air conditioning to keep the temperature comfortable is a significant monetary and environmental cost. Hui Huang and his team want to develop “smart windows”, which would block the entry of heat but still allow in natural light. Huang says that in Singapore, air conditioning is the largest component of a building’s energy requirements, so even a small reduction in heat entering the building would give significant savings.

The coating developed by Huang and his team is based on 10 nm tin oxide nanoparticles doped with antimony. They use a solvothermal synthesis technique, in which the antimony and tin oxide precursors are heated under pressure in an autoclave.

Crucially, the solvothermal method allows the size of the nanoparticles to be closely controlled. Huang says that his nanoparticles are around twice as effective at blocking infrared light when coated onto glass as commercially-available antimony-doped tin powders, which are larger. The glass still transmits more than 80% of visible light.

“A local glass company supporting this project is interested in licensing this smart window technology with infrared shielding,” said Huang.

He adds that the coating could potentially be applied onsite to existing windows.

Materials & Design  DOI: 10.1016/j.matdes.2015.09.013