BOC BOC Building Automation and Controls 2 — Questions and Answers
Question 1: What communication protocol is most widely used for interoperability between BAS devices from different manufacturers?
- Modbus RTU only
- BACnet (Building Automation and Control Networks) (Correct answer)
- LonWorks exclusively
- Proprietary vendor protocols
Correct answer: BACnet (Building Automation and Control Networks)
BACnet is the ASHRAE/ANSI/ISO standard open protocol that allows devices from different manufacturers to communicate on a common network, enabling integrated building automation.
Question 2: What is an 'alarm management' feature in a BAS used for?
- Scheduling preventive maintenance work orders
- Notifying operators when a monitored point exceeds normal operating limits (Correct answer)
- Automatically restarting failed equipment
- Logging energy consumption data for billing
Correct answer: Notifying operators when a monitored point exceeds normal operating limits
Alarm management monitors designated points and generates notifications when values exceed defined thresholds, alerting operators to faults, equipment failures, or unsafe conditions.
Question 3: What is 'demand-controlled ventilation' (DCV) and what sensor drives it?
- Ventilation controlled by outdoor air temperature using a thermostat
- Ventilation rate modulated based on occupancy using CO₂ sensors (Correct answer)
- Ventilation scheduled by time-of-day programming
- Ventilation controlled by humidity sensors to prevent condensation
Correct answer: Ventilation rate modulated based on occupancy using CO₂ sensors
DCV uses CO₂ sensors as a proxy for occupancy; when CO₂ levels rise (more people), outdoor air flow increases, and when levels drop, ventilation is reduced to save energy.
Question 4: In building controls, what does an 'economizer' control strategy do?
- Reduces lighting levels during peak electricity hours
- Uses cool outdoor air for free cooling instead of mechanical refrigeration when conditions allow (Correct answer)
- Cycles the boiler off during unoccupied hours
- Balances airflow between supply and return fans
Correct answer: Uses cool outdoor air for free cooling instead of mechanical refrigeration when conditions allow
An economizer control opens outdoor air dampers when outdoor conditions are cool enough to meet cooling needs without running the compressor, reducing chiller or DX cooling energy.
Question 5: What is the purpose of 'optimal start' programming in a BAS?
- To start equipment at the earliest possible time regardless of conditions
- To calculate the latest start time that still brings the building to setpoint by occupancy (Correct answer)
- To stagger equipment starts to avoid electrical demand spikes
- To pre-cool the building during the hottest summer afternoons
Correct answer: To calculate the latest start time that still brings the building to setpoint by occupancy
Optimal start uses historical data and outdoor temperature to calculate the latest possible start time that allows the HVAC system to reach comfort setpoints just as occupancy begins.
Question 6: What is 'load shedding' in the context of building electrical demand management?
- Transferring electrical load to a backup generator
- Temporarily reducing non-critical electrical loads to avoid exceeding demand charge thresholds (Correct answer)
- Disconnecting a faulty circuit breaker remotely
- Balancing loads across three electrical phases
Correct answer: Temporarily reducing non-critical electrical loads to avoid exceeding demand charge thresholds
Load shedding strategically turns off or reduces non-critical loads (such as non-essential lighting or HVAC zones) during peak demand periods to stay below costly demand charge thresholds.
BOC BOC Building Automation and Controls 2
What communication protocol is most widely used for interoperability between BAS devices from different manufacturers?