HVAC Building Automation Systems

Question 1

What does the acronym 'BAS' stand for in commercial HVAC?

Accepted Answer

Building Automation System

Answer

BAS stands for Building Automation System. A BAS integrates control of HVAC, lighting, fire, security, and other building systems through a centralized, computer-based control platform.

Question 2

What communication protocol is most widely used for BAS integration in commercial HVAC?

Accepted Answer

BACnet

Answer

BACnet (Building Automation and Control Networks) is the ASHRAE/ANSI standard communication protocol (ASHRAE 135) most widely used for BAS integration. It allows devices from different manufacturers to communicate on the same network.

Question 3

What is a 'DDC' controller in a building automation system?

Accepted Answer

Direct Digital Control — uses microprocessors to control HVAC equipment based on sensor inputs

Answer

DDC (Direct Digital Control) uses microprocessor-based controllers to receive sensor inputs, execute control logic, and send output commands to HVAC equipment. DDC replaced pneumatic and analog electronic controls in modern systems.

Question 4

What is the purpose of a Variable Air Volume (VAV) box in a BAS-controlled system?

Accepted Answer

To modulate airflow to individual zones to maintain zone temperature setpoints

Answer

A VAV box is a terminal unit that modulates the volume of conditioned air delivered to a zone by adjusting a damper. The BAS controls each VAV box to maintain the zone's temperature setpoint, allowing individual zone control.

Question 5

What is 'demand-controlled ventilation' (DCV) and what sensor drives it?

Accepted Answer

Outdoor air ventilation modulated based on actual occupancy, driven by CO2 sensors

Answer

DCV uses CO2 sensors to measure occupancy-related CO2 levels and adjusts outdoor air intake to match actual occupancy. When CO2 rises, more outdoor air is introduced; when occupancy drops, outdoor air is reduced, saving energy.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC Building Automation Systems