This book is as wide-ranging as the standard itself, covering not just hvac but also administration, enforcement, building envelope design, water heating, lighting, etc.
"An efficient (hvac) system is not merely one that uses efficient equipment. System interactions play a major role in the overall system efficiency. Particularly for systems that serve multiple zones, the efficiency of the air and water distribution systems and how they are controlled can be much more important factors in determining overall hvac system performance than the efficiency of each piece of equipment."
So begins chapter 6 in ASHRAE's newly released (Standard) "90.1 User's Manual." Rather than just announcing a new standard to be implemented, in this case "Energy standard for buildings except low-rise residential buildings," ASHRAE wisely decided to put together a sound compendium of actual examples and helpful hints, charts and graphs for compliance.