Smart glass developer Southwall Technologies has created a new approach called Heat Mirror Quad-Cavity R20 insulating glass that is at the center of a new line of window panes that offer either solar heating (when it is cold) or solar shading (when it is warm).
Heat Mirror uses a multi-cavity approach -- four cavities to be specific -- to create climate-appropriate insulation. The glass offers an R20 insulating value at the weight of a dual-pane insulating glass (IG) pane. The Quad-Cavity R20 panes suspend the Heat Mirror film within the glass layers, creating four independent airspaces. Different combinations of film and glass can be applied to optimize performance for either cold or hot climates. The entire pane itself is 1 and 3/4 inches thick, not exactly what you'd want in your home perhaps, but definitely appropriate for commercial applications.
The company is pitching the new technology as a more energy-efficient alternative to insulated walls in some construction configurations.