US Green Building Council LEED-AP-Homes Exam - Topic 7 Question 4 Discussion

The LEED for Homes Rating System (v4) requires blower door testing in the Energy and Atmosphere (EA) Credit: Air Infiltration to measure envelope leakage, expressed as air changes per hour (ACH) at a specific pressure differential.

According to the LEED Reference Guide for Homes Design and Construction (v4):

EA Credit: Air Infiltration (1--3 points)

Conduct a blower door test to measure envelope leakage in air changes per hour (ACH) at a pressure differential of 50 pascals (Pa). This standardizes the measurement of air tightness across projects.

Source: LEED Reference Guide for Homes Design and Construction, v4, Energy and Atmosphere Credit: Air Infiltration, p. 124.

The LEED v4.1 Residential BD+C rating system confirms:

EA Credit: Air Infiltration

Envelope leakage is measured using a blower door test at 50 pascals, reported as ACH50, to assess the airtightness of the building envelope.

Source: LEED v4.1 Residential BD+C, Credit Library, accessed via USGBC LEED Online.

The correct answer is 50 pascals (Option B), as this is the standard pressure differential for measuring ACH in LEED for Homes.

Why not the other options?

A . 25 pascals: This is not the standard pressure for ACH measurements in LEED or ENERGY STAR protocols.

C . 75 pascals: Higher pressures are not used, as 50 pascals is the industry standard for consistency.

D . 100 pascals: This is too high and not used in residential testing standards.

The LEED AP Homes Candidate Handbook emphasizes EA credits, including air infiltration testing, and references the LEED Reference Guide for Homes Design and Construction as a key resource. The exam is based on LEED v4, ensuring the relevance of the 50-pascal standard.

References:

LEED Reference Guide for Homes Design and Construction, v4, USGBC, Energy and Atmosphere Credit: Air Infiltration, p. 124.

LEED v4.1 Residential BD+C, USGBC LEED Credit Library, accessed via LEED Online (https://www.usgbc.org/credits).

LEED AP Homes Candidate Handbook, GBCI, October 2024, p. 12 (references study resources and exam scope based on LEED v4).

USGBC LEED for Homes Rating System (v4), available via USGBC website (https://www.usgbc.org/resources/leed-homes-design-and-construction-v4).

LEED v4.1 for Homes, USGBC, accessed via LEED Online, confirming ACH50 testing standard.