To achieve the point for this option under the LEED for Homes (2008) standard, the project must insulate all hot water pipes with a minimum thermal resistance value of R-4. This requirement applies to all pipes carrying hot water, including those from the water heater to fixtures. The purpose is to minimize standby heat loss as water sits in the pipes or travels to its destination, thereby conserving energy and reducing the time it takes to get hot water at the tap. This R-4 value is also referenced for recirculation loops in newer versions of the rating system (LEED v4/v4.1).

A. R-2: This insulation value is insufficient to meet the credit's minimum thermal resistance requirement.

B. R-3: This value is below the prescriptive minimum of R-4 mandated by the credit language for earning the point.

D. R-10: While higher insulation values are beneficial, R-10 exceeds the minimum requirement and is not the specified value for credit compliance.

1. U.S. Green Building Council. (2008). LEED for Homes Rating System. Page 68, Credit EA 4: Efficient Hot Water Distribution, Option 3: Pipe Insulation. The text states, "Insulate all hot water pipes with a minimum of R-4 insulation."

2. U.S. Green Building Council. (2021). LEED v4.1 Residential: Single Family Homes. Page 10, EA Credit: Efficient Hot Water Distribution, Option 2: Central Water Heater with Recirculation System. This more recent standard maintains the R-4 requirement for specific applications, stating, "All pipes in the recirculation loop must be insulated to at least R-4."