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ENERGY EFFICIENCY.  Preliminary data show that this emerging technology can reduce overall cooling loads by up to 20%. Additionally, the dynamic nature of this glazing may improve the performance of daylight harvesting luminaires, yielding additional energy savings.

COST EFFECTIVENESS.  The products are new and emerging. Material costs are negotiated as the products do not have standard production runs. Energy savings, occupant behavior, and the potential to reduce HVAC equipment size will be evaluated, and cost / benefit calculated at different price points.

OPERATIONS AND MAINTENANCE.  Thermotropic windows would have operations and maintenance (O&M) similar to conventional windows; electrochromic windows require a controlled power source integrated into the window frame. Occupant acceptance of these products is unknown. Electrochromic windows provide local occupant control, while thermotropic windows do not provide control of their level of tinting.

APPLICABILITY.  Smart window glazing materials can be adapted to any glazing application (e.g., interior partitions, exterior windows, skylights). The technology is most applicable to new construction and major reconstruction where the capital cost can be offset by the downsized HVAC equipment cost. On a retrofit basis, this technology may be more difficult to justify on a cost/benefit basis.
 

Adapted from report by Pacific Northwest National Laboratory.