Accelerated aging of treated aluminum for use as a cool colored material for facades

Abstract

Cool colored materials like membrane sheets and dried coatings exhibit higher reflectances in the near infrared region compared to conventional materials of the same color and are therefore desirable, as they provide energy economy and thermal comfort in cooling-dominated climates. They can also make reflective envelopes durable, owing to their lower surface temperatures. In this study, we experimentally show that different types of treated aluminum, like electrolytically anodized aluminum and aluminum with highly reflective baked-on coatings, can be employed as cool colored materials. Dark brown and light brown samples were examined in an accelerated aging test, and the optical properties and surface colors of the samples were compared with those of steels with reflective dried-on coatings. The treated aluminum samples exhibited stable optical properties and were durable. The accelerated aging tests, which involved exposure to ultraviolet radiation, heat, and water, were considered equivalent to actual long-term exposure, as evident from the decrease in gloss values of the samples. The aging conditions did not have a significant impact on the reflectances of the treated aluminum samples. Instead, our findings strongly suggest that the change in the reflectances of the tested samples may be due to accumulation of soil/dust and not due to surface aging.