The LEED for Homes Rating System (v4) includes the Indoor Environmental Quality (EQ) Credit: Radon Control, which promotes radon-resistant construction techniques to mitigate the health risks of radon gas, a naturally occurring radioactive gas that can accumulate in homes.

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

EQ Credit: Radon Control (1 point)

Install a passive or active radon-resistant system, including a vent pipe extending from below the foundation (e.g., sub-slab or crawlspace) to the roof to exhaust radon gases before they enter the home. This is a primary radon-resistant construction technique.

Source: LEED Reference Guide for Homes Design and Construction, v4, Indoor Environmental Quality Credit: Radon Control, p. 150.

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

EQ Credit: Radon Control

A vent pipe to exhaust gases from under the home (e.g., sub-slab depressurization system) is a key radon-resistant technique, preventing radon entry into living spaces.

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

The correct answer is vent pipe to exhaust gases from under the home (Option A), as this is a standard radon-resistant technique, typically involving a sub-slab depressurization system with a vent pipe.

Why not the other options?

B . Pressurized basement or crawlspace to prevent gases from entering the home: Pressurization can reduce infiltration but is not a standard radon-resistant technique; depressurization (via venting) is preferred.

C . Perforated foundation slab to allow air circulation: Perforated slabs are not a recognized radon-resistant method; they may increase radon entry by allowing gas to flow into the home.

D . Continuously operating bath fans to remove gases from inside the home: Bath fans address general ventilation, not radon-specific mitigation, which requires sub-slab venting.

The LEED AP Homes Candidate Handbook emphasizes EQ credits, including radon control, 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 vent pipe systems.

References:

LEED Reference Guide for Homes Design and Construction, v4, USGBC, Indoor Environmental Quality Credit: Radon Control, p. 150.

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 radon-resistant techniques.