Please raise your hand if you enjoy having two energy codes providing the standard of care for your projects. For most of the U.S., this is the dilemma for every building project. Though most jurisdictions adopt the International Energy Conservation Code (IECC) published by the International Code Council (ICC), ASHRAE 90.1 remains enforced by many institutions, such as the U.S. Green Building Council (USGBC).
Further, the IECC references ASHRAE 90.1 as a compliance path. This paper will ignore Title 24 (California Energy Commission, 2019), which is as much an outlier as California, the state that mandates it. Though the codes try to coexist like friendly allies, they seem to pair more like the mongoose and cobra. Why does the design community continue to accept this bifurcation of such a vital part of our design basis?