New passive cooling material for buildings

New Cooling Technology for Buildings Works In the Full Heat of a Sunny Day – electrical engineers at Stanford have discovered a “metal-dielectric photonic structure” that

• acts like a mirror to solar light reflecting the Sun’s energy,
• emits what it reflects within a specific range of wavelength to not contribute to the greenhouse effect.

This brief article goes on to say:

The net cooling exceeds 100 watts per square meter, about the same amount of power as current solar panels generate at 10% efficiency. A single-family home clad in this new material could easily reduce its air conditioning needs by 35% or more even on the hottest summer days, and do this without drawing on any power source.

From Stanford’s press release:

The Stanford team has succeeded where others have come up short by turning to nanostructured photonic materials. These materials can be engineered to enhance or suppress light reflection in certain wavelengths.

“We’ve taken a very different approach compared to previous efforts in this field,” said Aaswath Raman, a doctoral candidate in Fan’s lab and a co-first-author of the paper. “We combine the thermal emitter and solar reflector into one device, making it both higher performance and much more robust and practically relevant. In particular, we’re very excited because this design makes viable both industrial-scale and off-grid applications.”