The GreenGirt CMH XO continuous insulation system for windows is a composite metal hybrid sub-framing system used to provide the necessary structural support and thermal breaks by bringing windows into alignment with the thermal plane of a building’s continuous insulation. The GreenGirt CMH XO addresses the thermal loss at window openings by eliminating through-wall metal, through-insulation fasteners, conductive metal angles and inefficient wood-blocking, as well as increases the R-value of a window opening to +90%.