There is a serious desire among designers of direct digital control (DDC) systems for a better understanding of this technology, too often perceived as "black box magic". As HVAC system designers learn more about the structuring of DDC programs, the nature of communication protocols, and the capabilities of today's central operator stations, they will design more synergistic and useful control and management applications that are more consistent with the power of the specified processors. Through the specification of more and more powerful graphic displays, a much better understanding of DDC and the HVAC system will prevail, and building management system (BMS) users will be more effective. In addition to suggestions for better DDC/BMS "system" applications, there are also (from a vendor's perspective) constructive comments related to the balance of the DDC/BMS system specifications.

KEYWORDS: planning, specifications, documentation, computer controls, building management, controls, building services, heating, air conditioning, ventilation.