25 practical HVAC design questions based on ASHRAE Standards

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🧠 ASHRAE-Based HVAC Design MCQs



🌬️ ASHRAE 62.1 & 62.2 – Ventilation and IAQ

  1. ASHRAE 62.1 defines minimum outdoor air ventilation rates based on:

    1. Building height
    2. Occupancy type and area
    3. HVAC system type
    4. Climate zone
      ✔️ Answer: b. Occupancy type and area
      Ventilation Rate Procedure uses people + area components.

  2. ASHRAE 62.2 applies primarily to:

    1. Hospitals
    2. Commercial buildings
    3. Residential dwellings
    4. Industrial facilities
      ✔️ Answer: c. Residential dwellings
      Focuses on IAQ in low-rise homes and apartments.

  3. ASHRAE 62.1 recommends CO₂ levels not exceed:

    1. 700 ppm
    2. 1000 ppm
    3. 1200 ppm
    4. 1500 ppm
      ✔️ Answer: b. 1000 ppm
      Relative to outdoor air, for acceptable IAQ.

  4. Ventilation effectiveness in ASHRAE 62.1 is highest when:

    1. Supply and return are on the same wall
    2. Air is supplied near the ceiling and returned low
    3. Air is supplied low and returned high
    4. Air is recirculated only
      ✔️ Answer: c. Air is supplied low and returned high
      Promotes displacement ventilation.

  5. ASHRAE 62.2 requires kitchen exhaust to be:

    1. Recirculated
    2. At least 100 cfm continuous
    3. Ducted to outdoors
    4. Filtered only
      ✔️ Answer: c. Ducted to outdoors
      To remove cooking contaminants.

🌡️ ASHRAE 55 – Thermal Comfort

  1. ASHRAE 55 defines acceptable indoor temperature range for comfort as:

    1. 68–74°F
    2. 70–78°F
    3. 72–80°F
    4. 75–82°F
      ✔️ Answer: b. 70–78°F
      Depends on clothing and activity level.

  2. ASHRAE 55 considers which factors for thermal comfort?

    1. Temperature only
    2. Humidity and air speed
    3. Clothing, activity, temperature, humidity, air speed
    4. HVAC system type
      ✔️ Answer: c. Clothing, activity, temperature, humidity, air speed
      All influence perceived comfort.

  3. Maximum recommended air speed in occupied zones for cooling comfort:

    1. 20 fpm
    2. 40 fpm
    3. 60 fpm
    4. 80 fpm
      ✔️ Answer: d. 80 fpm
      Higher speeds may cause draft discomfort.

  4. ASHRAE 55 allows elevated air speeds only when:

    1. Humidity is below 30%
    2. Occupants wear light clothing
    3. Operable controls are provided
    4. Ceiling fans are used
      ✔️ Answer: c. Operable controls are provided
      Gives occupants control over comfort.

  5. Acceptable indoor relative humidity range per ASHRAE 55:

    1. 20–40%
    2. 30–60%
    3. 40–70%
    4. 50–80%
      ✔️ Answer: b. 30–60%
      Balances comfort and mold risk.

⚡ ASHRAE 90.1 & 90.2 – Energy Efficiency

  1. ASHRAE 90.1 applies to:

    1. Residential buildings only
    2. Commercial buildings
    3. Industrial buildings
    4. All buildings
      ✔️ Answer: b. Commercial buildings
      Sets minimum energy efficiency standards.

  2. ASHRAE 90.2 applies to:

    1. High-rise offices
    2. Warehouses
    3. Low-rise residential buildings
    4. Hospitals
      ✔️ Answer: c. Low-rise residential buildings
      Focuses on homes and small dwellings.

  3. ASHRAE 90.1 mandates economizers for systems over:

    1. 33,000 BTU/hr
    2. 65,000 BTU/hr
    3. 135,000 BTU/hr
    4. 300,000 BTU/hr
      ✔️ Answer: c. 135,000 BTU/hr
      Encourages free cooling when outdoor air is favorable.

  4. ASHRAE 90.1 requires VAV fan systems to have:

    1. Fixed speed motors
    2. Manual dampers
    3. Variable speed drives
    4. No controls
      ✔️ Answer: c. Variable speed drives
      Improves part-load efficiency.

  5. ASHRAE 90.2 recommends HVAC equipment selection based on:

    1. Lowest cost
    2. Highest SEER rating
    3. Climate zone and load
    4. Manufacturer preference
      ✔️ Answer: c. Climate zone and load
      Tailors efficiency to location.

🔍 ASHRAE 173 – Ventilation Performance Verification

  1. ASHRAE 173 focuses on:

    1. Thermal comfort
    2. Energy modeling
    3. Ventilation performance testing
    4. Refrigerant safety
      ✔️ Answer: c. Ventilation performance testing
      Verifies actual airflow and contaminant removal.

  2. ASHRAE 173 recommends using which method for airflow verification?

    1. Visual inspection
    2. Smoke test
    3. Flow hood or balometer
    4. Thermometer
      ✔️ Answer: c. Flow hood or balometer
      Quantifies supply/exhaust rates.

  3. ASHRAE 173 is most applicable during:

    1. Design phase
    2. Construction
    3. Commissioning
    4. Warranty period
      ✔️ Answer: c. Commissioning
      Ensures systems meet design intent.

🧯 ASHRAE 15 – Refrigerant Safety

  1. ASHRAE 15 limits refrigerant concentration in occupied spaces to prevent:

    1. Fire
    2. Toxic exposure
    3. Noise
    4. Vibration
      ✔️ Answer: b. Toxic exposure
      Protects occupant health.

  2. ASHRAE 15 requires refrigerant leak detection in:

    1. All systems
    2. Systems over 50 lbs charge
    3. VRF systems only
    4. Residential split ACs
      ✔️ Answer: b. Systems over 50 lbs charge
      Triggers alarms and ventilation.

  3. ASHRAE 15 mandates ventilation for refrigerant machinery rooms at:

    1. 1 ACH
    2. 3 ACH
    3. 5 ACH
    4. 10 ACH
      ✔️ Answer: c. 5 ACH
      Ensures dilution of leaks.

  4. ASHRAE 15 classifies refrigerants based on:

    1. Cost and availability
    2. Toxicity and flammability
    3. Pressure and temperature
    4. Manufacturer
      ✔️ Answer: b. Toxicity and flammability
      Groups refrigerants into safety classes.

  5. ASHRAE 15 requires emergency shutoff for:

    1. All chillers
    2. Systems with remote condensers
    3. Systems in machinery rooms
    4. Systems with R-22
      ✔️ Answer: c. Systems in machinery rooms
      To isolate leaks quickly.

  6. ASHRAE 15 requires alarms to activate when:

    1. Temperature exceeds 100°F
    2. Pressure exceeds 300 psi
    3. Refrigerant concentration exceeds threshold
    4. Humidity drops below 30%
      ✔️ Answer: c. Refrigerant concentration exceeds threshold
      Protects occupants from exposure.

  7. ASHRAE 15 compliance is critical for:

    1. Comfort
    2. IAQ
    3. Safety
    4. Efficiency
      ✔️ Answer: c. Safety
      Prevents hazardous conditions.


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