Door openings are integral to the building envelope. As such, they should be designed as effective barriers to thermal transmission, air infiltration and energy loss. ASSA ABLOY’s Trio-E, energy efficient door opening solution, comprises a (steel-stiffened, insulated) hollow metal door, a (thermally-broken) frame and threshold; and, (latching/hanging/closing) hardware that when combined, achieve an operable U-value of 0.29, one of the best ratings in the industry.