Practice Test Geeks(HERS) Home Energy Rater Certification Practice Test
← All HERS Flashcard Decks

Blower Door & Air Infiltration Flashcards

7 cards from real HERS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Blower Door & Air Infiltration flashcards as text

  1. A blower door test is conducted at a pressure difference of 50 Pascals. What does the CFM50 value represent?

    Answer: The airflow in cubic feet per minute needed to maintain 50 Pa across the building envelope

    CFM50 is the volumetric airflow (in cubic feet per minute) required to maintain a 50 Pa pressure differential across the building envelope during a blower door test.

  2. Which component of the blower door system measures the pressure difference between inside and outside the building?

    Answer: Manometer

    The manometer measures the pressure differential across the building envelope and across the blower door fan during testing.

  3. When converting CFM50 to Equivalent Leakage Area (ELA), which pressure reference is typically used in the US?

    Answer: 25 Pascals

    In the US, ELA is referenced at 4 Pa for Canadian standards, but the most common US reference for Effective Leakage Area is 4 Pa while ELA at 10 Pa is used in some protocols; however, RESNET typically uses 4 Pa — but the standard US ELA reference in blower door analysis is 4 Pa.

  4. A home has a volume of 15,000 cubic feet and measures 1,200 CFM50. What is the Air Changes per Hour at 50 Pascals (ACH50)?

    Answer: 4.8 ACH50

    ACH50 = (CFM50 × 60) / Volume = (1,200 × 60) / 15,000 = 72,000 / 15,000 = 4.8 ACH50.

  5. Which of the following building penetrations is MOST commonly identified as a major source of air leakage during blower door testing?

    Answer: Top plates and attic bypasses

    Top plates and attic bypasses — including gaps around ceiling electrical boxes, plumbing chases, and partition wall top plates — are among the largest sources of air leakage in residential buildings.

  6. During a blower door test, a technician notices the manometer reading is unstable and fluctuating. What is the MOST likely cause?

    Answer: Wind-induced pressure fluctuations on the exterior

    Wind-induced pressure fluctuations on the building exterior cause unstable manometer readings, which is why blower door tests should be conducted on calm days (wind speeds under 15 mph).

  7. What is the purpose of using multiple pressure rings (flow rings) in a Minneapolis Blower Door system?

    Answer: To allow accurate flow measurement across a wide range of leakage rates

    Different flow rings restrict airflow to different degrees, allowing the system to accurately measure both very tight and very leaky buildings within the fan's accurate measurement range.