Thermal Bridging Research: Mechanical Louvers

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 mechanical louvers.

The continuity of the thermal barrier can often be lost around the opening for mechanical louvers, another area in the exterior envelope system. The thermal loss around louvers, though not as significant as other thermal bridges studied, seems to be primarily a result of drawing coordination and construction sequencing. Because the insulation of the plenum is most often shown on the mechanical drawings and the wall system on the architectural drawings, details are frequently not coordinated to show the thermal continuity through the detail. The mechanical plenum drawings stop at the interior side of the wall, whereas the architectural drawing set most often shows the insulation remaining on the plane of the exterior, leaving a gap in the building envelope between the two systems. Coordinating drawings to show continuity of the thermal barrier from the envelope through to the mechanical plenum will improve the thermal performance around louvers.

In addition to the thermal bridges caused from the discontinuity between mechanical and architectural drawings, if a plenum is built sitting on the floor of the mechanical room, if often is uninsulated at this location. Louvers that can instead be supported intermittently to allow for the thermal barrier to pass across the envelope system with minimal thermal breaks will considerably improve thermal performance.

As-Built Condition, R-5.68

Thermally Improved Condition, R-6.53 (+15%): Masonry opening increased enough to allow insulation below (and around) louver.

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
Thermal Bridging Research: Metal Panel Wall Systems
Thermal Bridging Research: Parapets
Thermal Bridging Research: Transitions between Wall Systems
Thermal Bridging Research: Soffits
Thermal Bridging Research: Roof to Wall Transitions
Thermal Bridging Research: Roof Penetrations