Applied physicists at Columbia University have determined that using corrugated siding on outdoor building walls passively reduces wall temperatures.

To reach this conclusion, the team added corrugated siding to a small test building, which reportedly lowered the temperatures of the walls.

Conceptual illustration of the treated walls. Source: Nexus (2024). DOI: 10.1016/j.ynexs.2024.100028

Previous research has demonstrated that covering the tops of buildings with radiative cooling materials reduces the amount of heat from making its way inside the building by as much as 20%. The researchers explain that this is due to the way the material reflects sunlight and radiates heat into outer space. However, such materials have not been as successful when applied to the sides of buildings, due to the angles involved as well as the heat reflected from the ground.

To overcome this angle problem, the team applied corrugated materials, with their zig-zag patterns, to the sides of the small building model. Once applied, the team then painted the facets with two different materials. The surface facing up toward the sun was covered with emissive material, while the surface facing downward received a reflective coating.

Once the materials were applied to the building, the team then placed the model outside in the sun alongside a similar model with a standard wall covering and frequently checked the temperature of both, finding the average difference between the two was 2.3° C and that the difference was 3.1° C during the hottest part of the day.

The findings are detailed in the article, “Realizing optimal radiative cooling walls in building-energy nexus via asymmetric emissivity,” which appears in the journal Nexus.