Thermal Bridging Research: Metal Panel Wall Systems

One of our many in-house research efforts is a large, collaborative project. We investigated the Thermal Performance of Façades through the AIA Upjohn Research Initiative.

Thermal bridging in building construction occurs when thermally conductive materials penetrate through the insulation creating areas of significantly reduced resistance to heat transfer. These thermal bridges are most often caused by structural elements that are used to transfer loads from the building envelope back to the building superstructure. Though design professionals generally understand that thermal bridging is a concern, few can quantify the extent of its impact on building performance.

Small changes in designs can still lead to dramatic improvements in performance. With careful detailing and attention to the issues of thermal bridging, the design and construction industry can improve the performance of our building envelopes.

Today we’re sharing our findings regarding metal panel wall systems.

Insulated metal wall panels are popular because they can be a simple and economic strategy for cladding a building. Because the insulation is integral to the cladding and is sandwiched between two metal skins, the cladding support structure does not act as a thermal bridge. However, we observed that the joints between the panels become critical to maintaining thermal integrity for the system. Due to different approaches to the joints, a large discrepancy was observed in the thermal images between the different options, with some at 60-70% less than the baseline R-value and others at only about 3% thermal degradation.

The joints were revealed to be the key difference between metal panels that perform poorly and those that performed well.  In the poor performing options, the metal front of the panel wraps through the joint, providing a thermal bridge that greatly undermines performance. The option that performed well, in both the infrared image and the simulation, was backstopped at the gap between connecting panels. The backstop was made of insulation which was wide enough to make a continuous thermal barrier. The simplicity of this joint detail shows how careful detailing can lead to a dramatic improvement in thermal performance.

Left: Metal Panel with Uninsulated Joints; Right: Metal Panel with Insulated Joints

Related:
Thermal Performance of Facades: Final Report
Thermal Bridging Research: Curtain Walls
Thermal Bridging Research: Investigating Insulation Thickness for Renovations
Thermal Bridging Research: Masonry Veneer Walls
Thermal Bridging Research: Window Transitions
Thermal Bridging Research: Foundation to Wall Transitions
Thermal Bridging Research: Rainscreens