ASHRAE Indoor Air Quality and Ventilation Standards 5 — Questions and Answers
Question 1: Under ASHRAE 62.1, what air class applies to commercial kitchen grease hood exhaust?
- Class 1
- Class 2
- Class 3
- Class 4 (Correct answer)
Correct answer: Class 4
Kitchen grease hood exhaust is Class 4, so it may not be recirculated or transferred.
Question 2: In a multiple-zone recirculating system under ASHRAE 62.1, how is outdoor air intake flow (Vot) determined?
- Vot = Vou × Ev
- Vot = Vou + Ev
- Vot = Vou / Ev (Correct answer)
- Vot = Vbz / Ez
Correct answer: Vot = Vou / Ev
Uncorrected outdoor air Vou is divided by system ventilation efficiency Ev, which is less than 1, so the intake must increase.
Question 3: What zone air distribution effectiveness (Ez) does ASHRAE 62.1 assign to low-velocity displacement ventilation (cool air supplied at the floor, ceiling return)?
- 0.8
- 1.0
- 1.2 (Correct answer)
- 1.5
Correct answer: 1.2
Displacement ventilation moves contaminants upward out of the breathing zone and earns Ez = 1.2.
Question 4: Under ASHRAE 170, what are the minimum total and outdoor air change rates for an operating room?
- 12 total ACH, 2 outdoor ACH
- 20 total ACH, 4 outdoor ACH (Correct answer)
- 15 total ACH, 3 outdoor ACH
- 25 total ACH, 5 outdoor ACH
Correct answer: 20 total ACH, 4 outdoor ACH
Standard 170 requires 20 total ACH and 4 outdoor ACH, with positive pressure, for operating rooms.
Question 5: Per ASHRAE 170, an airborne infection isolation (AII) room must have which pressure relationship and minimum total air change rate?
- Positive pressure, 12 ACH
- Negative pressure, 6 ACH
- Neutral pressure, 12 ACH
- Negative pressure, 12 ACH (Correct answer)
Correct answer: Negative pressure, 12 ACH
AII rooms are held negative to adjacent spaces at a minimum of 12 total ACH to contain infectious aerosols.
Question 6: For a naturally ventilated zone under ASHRAE 62.1, what minimum openable area is required as a percentage of net occupiable floor area?
- 4% (Correct answer)
- 2%
- 8%
- 10%
Correct answer: 4%
62.1 requires openings of at least 4% of the net occupiable floor area of the ventilated space.
Question 7: What is the main goal of demand-controlled ventilation (DCV) in buildings designed to ASHRAE 62.1?
- Keep outdoor air fixed at design maximum
- Reset outdoor air intake based on actual occupancy (Correct answer)
- Raise supply air temperature at part load
- Remove the need for exhaust in toilet rooms
Correct answer: Reset outdoor air intake based on actual occupancy
DCV lowers outdoor air when occupancy drops, often using CO2 or occupancy sensors, while still meeting 62.1 rates.
ASHRAE Indoor Air Quality and Ventilation Standards 5
Under ASHRAE 62.1, what air class applies to commercial kitchen grease hood exhaust?