Darker colors absorb more heat energy, which increases thermal bowing. Examining the exterior panel color, temperature of the interior of the building based on end use, panel type, structural support framing, and design loads allows building engineers to calculate the amount of thermal bow within acceptable limits. In addition, the orientation and profile of the panel can span from 1.22 m (4 ft) to 2.44 m (8 ft). The use of flat, ribbed, and embossed profiles helps determine the span of the panel and reduction steel needed.
Although thermal bow is not a limiting factor for commercial and industrial applications of IMPs, it is a key consideration for cold storage, due to the notable temperature difference between the interior and exterior panels. To reduce unnecessary heat on the exterior, along with the thermal bow, cold storage facilities generally specify white or light-colored panels.
Building for aesthetics and durability
Architects who specify metal panels as exterior cladding can choose from a wide variety of configurations, textures, and colors for IMPs or single-skin panels. IMPs allow design freedom to build creatively while capitalizing on the performance benefits available.
Single-skin panels possess another downside when it comes to aesthetics: oil canning. Thinner panels begin to have a wavy or distorted appearance after long-term heat exposure, which causes them to ripple and buckle. There are three environmental or production forces which can cause this to occur:
- When it is hot outside and the steel expands outward. Once it is screwed into a fixed material and held back, the panel starts stretching and forms waves.
- The production process, which applies stress to the panel. This can make the steel longer in the middle than on the sides and create ripples, sometimes known as “full-feathering.” It can also occur in the opposite manner, with wavy edges occurring from being too long on the outside. Lastly, it can camber and maintain the curl of the coil.
- The memory of the steel making the panel want to return to the original coil, causing waves to appear.