Minimizing envelope leakage is a critical component of improving energy efficiency in homes, as it reduces unintended air infiltration and exfiltration through the building envelope. This concept is addressed in theLEED for Homes Rating System (v4)under theEnergy and Atmosphere (EA)category, specifically in credits related toAir InfiltrationandBuilding Envelope Performance.
According to theLEED Reference Guide for Homes Design and Construction (v4), the primary method to minimize envelope leakage is to install acontinuous air barrier:
EA Prerequisite: Minimum Energy Performance
To reduce air infiltration, projects must include a continuous air barrier system that is sealed at all penetrations, joints, and interfaces to prevent air leakage. The air barrier must be installed around the entire building envelope, including walls, roofs, and floors.
Source: LEED Reference Guide for Homes Design and Construction, v4, Energy and Atmosphere Prerequisite: Minimum Energy Performance, p. 112.
Additionally, theLEED v4.1 Residential BD+Crating system reinforces this requirement:
EA Credit: Air Infiltration
Install a continuous air barrier system to control air leakage through the building envelope. The air barrier must be airtight, durable, and continuous, with all seams, penetrations, and transitions sealed.
Source: LEED v4.1 Residential BD+C, Credit Library, accessed via USGBC LEED Online.
Acontinuous air barrieris a system of materials (e.g., house wraps, sealed drywall, or spray foam) that forms a complete barrier to air movement, significantly reducing energy losses due to leakage. This is a proactive design and construction strategy to achieve energy efficiency goals.
Why not the other options?
[Reference: LEED Reference Guide for Homes Design and Construction, v4, Sustainable Sites Credit: Rainwater Management, p. 76, which discusses drainage planes in the context of moisture control., B. Conducting a blower door test: A blower door test is a diagnostic tool used tomeasureair leakage in a building, not to minimize it. It quantifies the air tightness of the envelope (in air changes per hour, ACH) but does not physically reduce leakage. It is required for verification in LEED v4 (EA Credit: Air Infiltration) but is not a solution for minimizing leakage.Reference: LEED Reference Guide for Homes Design and Construction, v4, EA Credit: Air Infiltration, p. 124., D. Specifying HERS Grade II Insulation: HERS (Home Energy Rating System) insulation grades refer to the quality of insulation installation, with Grade II indicating moderate defects. While proper insulation reduces conductive heat loss, it does not directly address air leakage, which is managed by the air barrier system.Reference: LEED Reference Guide for Homes Design and Construction, v4, EA Credit: Insulation, p. 120, which discusses HERS insulation grades but not air leakage., TheLEED AP Homes Candidate Handbookemphasizes the importance of understanding EA credits, including air infiltration, for the exam, referencing theLEED Reference Guide for Homes Design and Constructionas a key study resource. The handbook confirms that the exam is based onLEED v4, ensuring the relevance of the continuous air barrier requirement., References:, LEED Reference Guide for Homes Design and Construction, v4, USGBC, Energy and Atmosphere Prerequisite: Minimum Energy Performance, p. 112, and EA 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 air barrier requirements., ]
