Building Engineering HVAC and Building Mechanical Systems 1 — Questions and Answers
Question 1: What does ASHRAE Standard 62.1 govern in building design?
- Ventilation for acceptable indoor air quality (Correct answer)
- Thermal comfort in occupied spaces
- Energy efficiency of HVAC systems
- Refrigerant management and recovery
Correct answer: Ventilation for acceptable indoor air quality
ASHRAE 62.1 establishes minimum ventilation rates and IAQ requirements for commercial and institutional buildings.
Question 2: What refrigerant is widely used in commercial HVAC systems as a replacement for R-22?
- R-410A (Correct answer)
- R-11
- R-12
- R-502
Correct answer: R-410A
R-410A became the dominant replacement for R-22 in commercial split systems after the phase-out of ozone-depleting CFC and HCFC refrigerants.
Question 3: What is the primary function of a Variable Air Volume (VAV) box in an HVAC system?
- To modulate the volume of conditioned air delivered to a zone (Correct answer)
- To vary the refrigerant flow to air handlers
- To control chiller capacity
- To regulate boiler output
Correct answer: To modulate the volume of conditioned air delivered to a zone
A VAV box uses a damper and controller to vary airflow to each zone in response to thermostat demand, saving fan energy compared to constant volume systems.
Question 4: Which heat transfer fluid is commonly circulated through chilled water HVAC systems?
- Chilled water at 40–45°F (Correct answer)
- Refrigerant R-410A
- Steam at 15 psig
- Hot water at 180°F
Correct answer: Chilled water at 40–45°F
Chilled water systems circulate water cooled to 40–45°F from a central chiller to air handling units where it absorbs heat from return air.
Question 5: What is the purpose of an economizer in an HVAC air handling unit?
- To use outdoor air for free cooling when conditions are favorable (Correct answer)
- To recover heat from exhaust air
- To reduce refrigerant charge
- To pre-heat supply air in winter
Correct answer: To use outdoor air for free cooling when conditions are favorable
An air-side economizer opens dampers to bring in cool outdoor air instead of running mechanical cooling, reducing energy consumption significantly.
Question 6: What unit is used to measure the cooling capacity of HVAC equipment?
- Ton of refrigeration (Correct answer)
- BTU per hour only
- Kilowatt thermal
- Watt per square foot
Correct answer: Ton of refrigeration
One ton of refrigeration equals 12,000 BTU/hr and is the standard unit for rating cooling equipment capacity in the US.
Building Engineering HVAC and Building Mechanical Systems 1
What does ASHRAE Standard 62.1 govern in building design?