604 Energy Modeling

Dwelling Units shall be grouped for modeling purposes. At a minimum, all units within a group shall have the same number of bedrooms and conditioned floor area within 10 percent of one another (+/- 10%). For example, a group may contain only units with a given floor plan, or it may be a group of different floor plans assuming they all have the same number of bedrooms and are within +/-10% conditioned floor area. The Rater shall document which units are within each modeling group. Dwelling Units that satisfy these criteria, but differ in other criteria, are not required to be modeled as the same unit type.

A Worst-Case Analysis shall be performed to determine the model with the worst-case HERS Index for the group. The Worst-Case Analysis on a given group shall consider all variations in Minimum Rated Features and Threshold Specifications and shall also consider requirements of any relevant EEP. Every Dwelling Unit shall be assigned the HERS Index Score as determined by the worst-case analysis for the corresponding group.

If changes or adjustments are made to a Threshold Specification, the worst-case model must be updated accordingly and must still represent the worst-case analysis of all units within that group.

All units within a Sampling Project must be uploaded to the RESNET Building Registry. Each Dwelling Unit shall have an energy model identical to the worst-case model from its associated modeling group that specifies the individual address for that unit. Actual onsite Sampled Verification results for Sampled Features shall not be entered in the final Sampled Rating energy model uploaded to the RESNET Buildings Registry. Minimum Rated Features that are not Sampled, shall not be updated in the model to reflect actual onsite verifications.

At a minimum, a certified Rater shall oversee this process.