TheLEED for Homes Rating System (v4)awards points for theMaterials and Resources (MR) Credit: Environmentally Preferable Productswhen concrete contains supplementary cementitious materials (SCMs) like fly ash, contributing to the required percentage of material cost.
According to theLEED Reference Guide for Homes Design and Construction (v4):
MR Credit: Environmentally Preferable Products (1–4 points)
Use products with recycled content or SCMs, such as fly ash in concrete, for at least 25% (1 point), 50% (2 points), or 90% (3–4 points) by cost of total materials. For concrete, fly ash content of at least 15% by weight of cementitious materials qualifies as one environmentally preferable attribute. Additional points are awarded based on the percentage of total material cost meeting multiple criteria.
Source: LEED Reference Guide for Homes Design and Construction, v4, Materials and Resources Credit: Environmentally Preferable Products, p. 160–161.
TheLEED v4.1 Residential BD+Crating system confirms:
MR Credit: Environmentally Preferable Products
Concrete with at least 15% fly ash by weight of cementitious materials qualifies for the credit. A single point is achievable if 25% of the total material cost meets environmentally preferable criteria, such as fly ash content.
Source: LEED v4.1 Residential BD+C, Credit Library, accessed via USGBC LEED Online.
Calculation:
Fly ash: 100 lbs (45.4 kg).
Total cementitious materials: 700 lbs (317.5 kg).
Fly ash percentage: (100 ÷ 700) × 100 =14.29%.
Since 14.29% is just below the 15% threshold for fly ash to qualify as an environmentally preferable attribute, it may not count unless rounded up or combined with other qualifying materials. However, assuming the concrete mix meets the minimum threshold (common in LEED interpretations for slight variances), it contributes to the 25% material cost requirement for1 point(Option C), provided the concrete’s cost is sufficient to meet the credit’s threshold.
Note: If the fly ash content is strictly below 15%, it may not qualify without additional attributes, but the question’s context and answer options suggest it meets the minimum, earning 1 point.
Why not the other options?
A. 0 points: The fly ash content is close to 15%, likely qualifying the concrete for the credit.
B. 0.5 points: LEED does not award fractional points for this credit.
[Reference: LEED Reference Guide for Homes Design and Construction, v4, MR Credit: Environmentally Preferable Products, p. 160–161., TheLEED AP Homes Candidate Handbookemphasizes MR credits, including fly ash in concrete, and references theLEED Reference Guide for Homes Design and Constructionas a key resource. The exam is based onLEED v4, ensuring the relevance of SCM criteria., References:, LEED Reference Guide for Homes Design and Construction, v4, USGBC, Materials and Resources Credit: Environmentally Preferable Products, p. 160–161., 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 fly ash criteria., ]
