A thermal modeling comparison of typical curtainwall glazing systems

Lawrence D. Carbary, Associate Industry Scientist, Dow Corning Corporation & Fiby Albert, Application Engineer/Technical Service, Dow Corning Seneffe

This paper compares the U value and energy consumption of typical curtainwall glazing systems used in commercial buildings. These glazing practices are popular in the major cities of the world. There are four basic types of systems that are compared. 1) Glazing systems that use Insulating glass which are mechanically fixed in gaskets,2) 4 sided structural silicone glazed with wet weatherseals, 3) 4 sided structural silicone glazed with dry gasket weatherseal, and 4) Hybrid glazing system (structurally clamped).

The thermal modeling is performed based upon WinIso 2D using three different IG unit designs for the first three systems noted above. The IG unit designs evaluated are: 1) aluminium spacer 2) stainless steel spacer, and 3) warm edge spacer technology. The hybrid glazing system is modeled only with an aluminum spacer.

After calculating the U Value for a system, the results can be used to demonstrate how to evaluate the energy consumption for a specific system in a specific location, and compare these results relative to different configurations.

This paper details that mechanically fixed systems demonstrate good initial performance, but the aging of gaskets results in shrinkage. Furthermore, compression set of the gaskets allows additional air and water infiltration, rendering the system even less effective. Gasket joint systems also allow additional exposure to the elements of the middle of the aluminum system which further decreases the energy efficiency. Structural glazed systems using the warm edge technology provides an excellent U value and results in the most energy efficient system modeled .

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The Authors

Lawrence Carbary Associate Industry Scientist Dow Corning Lawrence D. Carbary is an Associate Industry Scientist for Dow Corning Corporation in the Construction Industry. He graduated from Michigan Technological University in July 1982 with a bachelors degre... Read more