In many ways, HVAC equipment is the most complex building system, with numerous components arranged to produce heating, cooling and ventilation through the principals of thermodynamics, fluid mechanics and heat transfer.
The HVAC system not only makes the building comfortable and healthy for its occupants, it manages a substantial portion of the energy consumed, as well as plays a critical role in life safety. In maintaining the building's air quality the HVAC system must respond to a variety of conditions inside and outside the building (including weather, time of day, different types of spaces within a building and building occupancy) and do so while optimizing its operation and related energy usage. Given the variety of conditions and the potential complexity of a substantial HVAC system this necessitates extensive automation and system integration. For example, in a smart building we expect the HVAC system to automatically sequence chillers, pumps, and boilers, as well as automatically rotate parallel chillers, pumps, and boilers by accumulated run-time. The HVAC system should also perform an optimal start calculation based upon real occupancy history instead of estimated start times.
Control of the HVAC system for occasional use facilities such as meeting rooms, conference rooms, and cafeterias is also important in reducing unnecessary energy consumption. HVAC for those spaces needs to be integrated into another system which can supply data to the HVAC system regarding use or occupancy. These include data from an access control system, video surveillance, a people counter system, lighting control, a RTLS/RFID system or more likely, occupancy sensors.
The HVAC system also plays a substantial role in a demand response events as well as demand limiting. Data from the utility or a power management system communicated to a BMS and chiller controls can be used to adjust the electric demand of the HVAC system to an acceptable level.