HERS Energy Modeling & Rating Systems 2 — Questions and Answers
Question 1: In REM/Rate software, what does the 'reference home' represent?
- The most efficient home in the neighborhood
- A standardized code-minimum home used as a baseline for HERS scoring (Correct answer)
- The rater's personal residence used for calibration
- The highest-performing home in the rating database
Correct answer: A standardized code-minimum home used as a baseline for HERS scoring
The reference home is a code-minimum home built to IECC specifications that serves as the 100-point baseline for HERS Index calculations.
Question 2: Which of the following inputs has the GREATEST impact on reducing a home's HERS score through envelope improvements?
- Window U-factor
- Ceiling insulation R-value
- Air leakage rate (ACH50) (Correct answer)
- Slab edge insulation
Correct answer: Air leakage rate (ACH50)
Air leakage (ACH50) typically has the greatest single impact on HERS scores because infiltration losses account for a large portion of a home's energy load.
Question 3: What is the standard test pressure used for blower door testing when collecting data for HERS ratings?
- 25 Pascals
- 50 Pascals (Correct answer)
- 75 Pascals
- 100 Pascals
Correct answer: 50 Pascals
HERS ratings use 50 Pascals (Pa) as the standard test pressure for blower door tests to measure envelope airtightness.
Question 4: A home is modeled with a gas furnace AFUE of 80% but the installed unit is 96% AFUE. How should the rater handle this?
- Use the 80% value since it was in the original model
- Update the model to reflect the 96% installed equipment (Correct answer)
- Average the two values for a 88% input
- Report the discrepancy to RESNET only
Correct answer: Update the model to reflect the 96% installed equipment
The energy model must reflect actual installed conditions; the rater must update equipment inputs to match what is installed in the home.
Question 5: When modeling a home with a conditioned crawl space in energy software, how should the crawl space be treated?
- As an unconditioned buffer zone with half R-value credit
- As part of the conditioned volume with insulated walls (Correct answer)
- As equivalent to a vented crawl space for simplified modeling
- As an outdoor space with no thermal boundary
Correct answer: As part of the conditioned volume with insulated walls
A conditioned crawl space is treated as part of the conditioned volume, with insulation on the crawl space walls rather than the floor above.
Question 6: What does the Benchmark HERS Index score of 100 specifically represent?
- A home that uses zero net energy annually
- A home built to the 2006 IECC energy code (Correct answer)
- A home with average U.S. energy consumption
- A home built to ENERGY STAR certification standards
Correct answer: A home built to the 2006 IECC energy code
A HERS Index of 100 represents the energy performance of a home built to the 2006 IECC, which is the RESNET reference standard.
Question 7: In energy modeling, what is 'internal gains' referring to?
- Solar heat gained through windows
- Heat generated by occupants, appliances, and lighting inside the home (Correct answer)
- Thermal bridging through structural members
- Ground heat transfer through the foundation
Correct answer: Heat generated by occupants, appliances, and lighting inside the home
Internal gains are heat sources within the conditioned space from occupants, lighting, and appliances that reduce heating loads but add to cooling loads.
HERS Energy Modeling & Rating Systems 2
In REM/Rate software, what does the 'reference home' represent?