Environmental control for HVAC system

An environmental control system for a building, the system comprising:

• a heating, ventilation and air-conditioning (HVAC) system configurable to change environmental aspects of the building to target parameters;
• a building automation system in communication with the HVAC system and configured to adjustably control at least one of the target parameters to a desired value;
• and
• an external application in communication with the building automation system and configured to evaluate equipment data received from the building automation system and to then process the equipment data to generate application data using an application control sequence, the external application provides the application data to the building automation system for controlling the HVAC system to achieve the desired value of the at least one of the target parameters,
• wherein the building automation system includes a sequence selector for determining whether to permit the external application to communicate with the HVAC system or disable communication between the external application and the HVAC system, and
• wherein the building automation system includes initialization data for operating the HVAC system at minimum stable level while the communication between the external application and the HVAC system is disabled.