Between-Pane Shading

Shading systems that are placed between two protective glazing layers require minimal maintenance and preserve high performance over the installation’s lifetime compared to its exterior counterpart, which can degrade due to dirt, snow, or ice accumulation. Between-pane shading systems are used in retail, sports arenas, lobbies, libraries, airports, and other applications with large area windows, sloped glazing, or skylights. Such systems are also increasingly used for conventional windows as energy codes become more stringent. Most commonly, the shading system is placed in a closed-cavity, insulating-glass unit. Double-envelope façade systems ventilate the cavity for heat recovery or rejection. Some systems are explicitly designed to also enhance daylighting through the selection of the shading material and geometry. LBNL has conducted research to characterize and evaluate the energy- and comfort-related performance of these systems as well as determine methods to improve performance.

A thin, perforated, angular-selective screen placed between low-e glazing layers (system G1R) can provide comparable or better energy savings performance than an exterior shading system (E3) without impairing view or requiring maintenance.  Annual energy use for a large commercial office building is lowest with the largest window area (x-axis).