The Emerging Role of Electronically Tintable Glass for Energy Codes and Standards

One of the core missions for today’s building codes is to progressively reduce the total energy consumption of modern buildings with each revision. Current three-year revisions of ASHRAE Standard 90.1 and IECC respectively target additional reductions of 20 and 30% over their earlier versions1. Designing attractive, cost effective buildings with such aggressive energy targets requires that all of the core systems of the building be improved, including the building facade. In addition to enabling the reduction of electric lighting with additional natural daylight, the properties (and behavior) and thermal performance of the façade affect the load that the heating and cooling systems see. All three taken together account for over 50% of the building’s energy consumption so must take first priority in efficient building design.

When one considers modern efficient facades, especially with regard to daylighting integration, the material class of tintable or dynamic glazing must be included. Dynamic glazing is an important advance in building materials whose that needs to be rapidly incorporated into today’s codes and standards. With the culmination of decades of research and refinements to the technology, the 2012 construction market will see multiple manufacturers release fully commercialized dynamic glazing products3. The availability these market ready products will provide architects with a cost effective façade system that can expand design possibilities and enable the creation of exceptionally energy efficient and comfortable daylit spaces that would otherwise not be possible4.

Unfortunately building codes and policy for the built environment have not kept pace with that of building materials technology. The current versions of the most important of these standards have yet to recognize the product category in any meaningful way. Because of this lag, our efficiency driven codes are creating an unforeseen barrier for tintable glazing. Without guidance on their preferred application or even their ultimate allowance, designers will be reluctant to dimming facades in their building designs. This paper will review the current state of the regulatory bodies with regard to dynamic glass and suggest a reasonable path forward.