ASHRAE ASHRAE Controls Automation and Building Systems Integration

Question 1

What communication protocol is widely recognized by ASHRAE as the standard for building automation and control network (BACnet) interoperability?

Accepted Answer

BACnet (ASHRAE Standard 135)

Answer

BACnet, defined in ASHRAE Standard 135, is the open communication protocol developed specifically for building automation and control systems to enable interoperability between devices from different manufacturers.

Question 2

In ASHRAE building control terminology, what is a 'setpoint' in a control loop?

Accepted Answer

The desired target value that the controller attempts to maintain for a controlled variable

Answer

A setpoint is the desired value for the controlled variable (such as room temperature or supply air pressure) that the control system continuously works to maintain.

Question 3

What type of control action does a proportional-integral-derivative (PID) controller use to eliminate steady-state offset in HVAC systems?

Accepted Answer

Integral action

Answer

Integral action in a PID controller accumulates the error over time and adjusts the output until the steady-state error (offset) is eliminated, which proportional-only control cannot achieve.

Question 4

According to ASHRAE guidelines, what is 'economizer control' in an air-handling unit?

Accepted Answer

A control strategy that uses outdoor air for free cooling when outdoor conditions are favorable, reducing mechanical cooling energy

Answer

Economizer control modulates the outdoor air damper to increase free cooling from outdoor air whenever outdoor conditions (temperature and/or enthalpy) allow, reducing or eliminating mechanical refrigeration.

Question 5

In ASHRAE Variable Air Volume (VAV) system controls, what is the primary variable that the VAV terminal unit modulates?

Accepted Answer

Airflow rate to the zone

Answer

A VAV terminal unit modulates the volume of conditioned supply air delivered to a zone to match the zone's varying cooling or heating load while maintaining a relatively constant supply air temperature.

ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers Certification Practice Test

ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers Certification Practice Test

ASHRAE ASHRAE Controls Automation and Building Systems Integration