A customizable smart window harnesses and manipulates solar power to save energy and cut costs.
Windows play multiple crucial roles in our homes. They illuminate, insulate and ventilate our spaces while providing views of—and protection from—the outdoors. Smart windows, or windows that
However, incorporating solar cells into windows while balancing the other complex, and often conflicting, roles of windows proves challenging. For example, juggling luminosity preferences and energy harvesting goals throughout changing seasons requires complex and strategic approaches to material design.
Scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, Northwestern University, the University of Chicago and University of Wisconsin-Milwaukee recently combined solar cell technology with a novel optimization approach to develop a smart window prototype that maximizes design across a wide range of criteria.
The optimization algorithm uses comprehensive physical models and advanced computational techniques to maximize overall energy usage while balancing building temperature demands and lighting requirements across locations and throughout changing seasons.
“This design framework is customizable and can be applied to virtually any building around the world,” said Junhong Chen, a scientist at Argonne and the Crown Family Professor of Molecular Engineering at the Pritzker School of Molecular Engineering at the University of Chicago. “Whether you want to maximize the amount of sunlight in a room or minimize heating or cooling efforts, this powerful optimization algorithm produces window designs that align with user needs and preferences.”
Advanced approach to optimization
The scientists demonstrated a wholistic approach to window design to maximize the overall energy efficiency of buildings while considering lighting and temperature preferences.
“We can regulate the sunlight in a room to ensure the desired luminosity while managing the amount of energy the building uses for heating and cooling,” said Wei Chen, the Wilson-Cook Professor in Engineering Design at Northwestern Engineering whose research group led the development of the optimization approach. “Additionally, the sunlight that doesn’t pass through is captured by the solar cell in the smart window and converted into electricity.”
The approach, called multicriteria optimization, adjusts thicknesses of solar cell layers in window design to meet the needs of the user. For example, to reduce the energy required to cool a building in the summer, the optimal window design might minimize the amount and type of light passing through while maintaining the desired luminosity inside. On the other hand, when winter savings are a priority, the design might maximize the amount of sunlight that passes through, thereby reducing the energy required for heating the building.