Attempts to mitigate solar heat gain and glare through glass curtain walls often involve electrified systems such as automatic blinds, active fritting, or tinting controlled by sensors and software. However, Doris Sung, Assoc. AIA, co-founder of New York– and Los Angeles–based TBM Designs, associate professor at the University of Southern California, and principal of Do|Su Studio Architecture has an elegant, new solution that relies on nothing but the mechanical properties innate to its materials. InVert Self-Shading Windows is Sung's latest exploration into thermobimetals, the subject of her two previous ARCHITECT R+D Award–winning projects: an active façade and a self-assembling structure.
—Juror Steve McDowell, FAIA
Thermobimetals consist of two different alloys laminated together. Because the two metals expand at different rates, the laminated sheet curls in different directions when heated or cooled, predictably and repeatedly, and with no degradation. Designed to be sealed within the cavity of an insulated glass unit, the InVert system consists of an array of bimetal pieces mounted on a stainless-steel network grid. When sunlight hits the window, the individual bimetal pieces warm and begin to curl, flipping into a new orientation that blocks the direct light.
After experimenting with 50-plus shapes and sizes for the pieces, Sung and her team settled upon a 0.0027-inch-thick notched ellipse that resembles a pair of butterfly wings. “The shape and size of the pieces are based on the performance of the material to curl and behave the way we want it to, and the performance of the system to block the right amount of sun,” Sung says. The angle of the V-shaped opening in which each piece sits controls the degree to which the piece can invert, allowing custom tuning for different climates and exposures.
TBM’s InVert system also preserves the color spectrum of incoming daylight, which researchers have linked to occupant wellness. It offers a visible light transmission level between 60% and 70%, and a solar heat gain coefficient of 0.37 when used with low-iron glass; use with coated glazing would bring the SHGC under 0.25.
Following a successful field test of two prototypes, Sung intends to manufacture the windows for the commercial market. The bimetal sheets, which were laser-cut for the prototype, will be die-stamped and shipped to a local IGU fabricator for new or retrofit curtain wall and storefront installations.
Project: InVert Self-Shading Windows
Company Name: TBM Designs, Los Angeles and Katonah, N.Y.
Architect/Designer/Inventor: Doris Sung, Assoc. AIA (DOSU Studio Architecture founder, University of Southern California associate professor, and TBM Designs co-founder)
Product Development Team: Justin Kang, Adelfrid Ramirez, Esther Ho, Stephanie Truong, Assoc. AIA, Lisa Phillips, Hung-Ming Chen, Rene Zarate, Thomas Gin, Belinda Pak, Assoc. AIA
Insulated Glass Unit Manufacturer: Triview Glass Industries (closed); Pulp Studio
Sales and Manufacturer: TBM Designs