ASHRAE Controls Automation and Building Systems Integration Flashcards
6 cards from real ASHRAE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ASHRAE Controls Automation and Building Systems Integration flashcards as text
According to ASHRAE, what is the purpose of 'demand-controlled ventilation (DCV)' in building HVAC control?
Answer: To modulate outdoor air ventilation rates based on actual occupancy measured by CO₂ sensors, saving energy when spaces are less than fully occupied
DCV uses CO₂ concentration as a surrogate for occupancy to dynamically adjust outdoor air ventilation rates, reducing over-ventilation of under-occupied spaces and saving fan and conditioning energy.
In ASHRAE chilled water plant controls, what is 'chiller sequencing'?
Answer: The staged start/stop and load distribution strategy for operating multiple chillers to maximize efficiency at varying building loads
Chiller sequencing determines when to start or stop additional chillers and how to distribute load among operating chillers to keep each unit operating near its most efficient point.
What is 'optimal start' control in building automation systems as referenced in ASHRAE guidelines?
Answer: An algorithm that calculates the latest possible startup time for HVAC equipment to achieve comfort conditions by occupancy, using current building thermal mass and outdoor conditions
Optimal start calculates the latest time to begin heating or cooling a building before occupancy based on current indoor/outdoor temperatures and the building's learned thermal response, saving energy versus fixed early-start schedules.
In ASHRAE building controls, what does 'reset control' (e.g., supply air temperature reset) accomplish?
Answer: It adjusts a control setpoint upward or downward in response to measured conditions to improve efficiency while maintaining comfort
Reset control varies a setpoint (such as chilled water or supply air temperature) based on outdoor air temperature or zone demand, allowing the plant to operate at less extreme conditions and save energy during mild weather.
According to ASHRAE, what is the role of a 'building automation system (BAS)' in modern HVAC operation?
Answer: To monitor and control all building mechanical, electrical, and life-safety systems from a centralized platform to optimize performance, comfort, and energy use
A BAS integrates and automates control of HVAC, lighting, and other building systems from a central supervisory platform, enabling energy optimization, fault detection, and remote monitoring.
In ASHRAE VAV system design, what is 'duct static pressure reset' and why is it recommended?
Answer: Reducing the duct static pressure setpoint as VAV boxes open toward maximum to save fan energy
Static pressure reset lowers the duct pressure setpoint when zone VAV dampers indicate they can be satisfied at lower pressure, allowing the supply fan to slow down and save significant energy.