HVAC systems represent the primary workload for most Building Management Systems. Effective control balances occupant comfort, energy efficiency, and equipment protection.
Heating Control
Commercial heating systems typically use compensated flow temperature control, adjusting boiler output based on external temperature. Zone control provides individual temperature regulation through modulating valves or variable speed drives. Sequencing multiple boilers maximises efficiency whilst maintaining capacity.
Cooling Control
Chilled water systems mirror heating control principles but with additional complexity. Chiller sequencing must respect minimum run times and avoid short cycling. Free cooling using outside air or adiabatic systems reduces compressor running hours when conditions permit.
Ventilation Control
Modern ventilation prioritises indoor air quality whilst minimising energy use. CO2-based demand controlled ventilation adjusts fresh air rates to actual occupancy. Heat recovery captures energy from extract air to pre-condition supply air. Variable speed fan control matches airflow to demand.
Air Handling Unit Control
AHU control integrates heating, cooling, and ventilation functions. Mixed air control optimises the balance between fresh and recirculated air. Supply air temperature reset adjusts setpoints based on zone demand. Proper sequencing ensures heating and cooling never operate simultaneously.
Common Pitfalls
Hunting and oscillation often indicate poor tuning or inadequate dead bands. Simultaneous heating and cooling wastes energy and indicates control conflicts. Regular review of trend data reveals these issues before comfort complaints arise.