Serious Materials, which recently acquired window innovator Alpen Energy Group, is tackling the wall’s most inefficient component with a new line of windows boasting unit R-values of 5 to 15. The company achieved this level, which is significantly higher than the R-2.5 to R-3 of a typical double-pane, low-E window, by reinventing the glass, the spacers, and the frame, says CEO Kevin Surace.