HERS HERS Index and Ratings Questions and Answers 1 — Questions and Answers
Question 1: A HERS Rater is explaining the HERS Index to a client. What does a HERS Index score of 100 signify?
- The home is 100% more efficient than a typical new home.
- The home has net-zero energy consumption.
- The home's energy performance is equivalent to that of the HERS Reference Home. (Correct answer)
- The home meets the minimum requirements for ENERGY STAR certification.
Correct answer: The home's energy performance is equivalent to that of the HERS Reference Home.
The HERS Index is a relative scale where 100 represents the energy performance of the HERS Reference Home, which is based on the 2006 International Energy Conservation Code (IECC). A lower score indicates better performance, and a higher score indicates worse performance.
Question 2: A newly constructed home receives a confirmed HERS Index of 65. How should the rater explain this result to the homeowner in terms of energy efficiency?
- The home is 65% less efficient than a Net Zero Energy Home.
- The home is 35% more energy efficient than a standard new home built to the HERS Reference Home specifications. (Correct answer)
- The home uses 65% of the energy that a standard new home uses.
- The home's energy efficiency is 35% below the current energy code requirements.
Correct answer: The home is 35% more energy efficient than a standard new home built to the HERS Reference Home specifications.
Each point below 100 on the HERS Index represents a 1% improvement in energy efficiency compared to the HERS Reference Home. Therefore, a score of 65 (100 - 65 = 35) means the home is 35% more energy efficient than the Reference Home.
Question 3: A builder is aiming for a home to achieve a HERS Index of 0. Which of the following is essential for achieving this specific score?
- Achieving an airtightness level of 1.0 ACH50 or less.
- Installing insulation levels that are double the local code requirements.
- Incorporating on-site renewable energy generation, such as solar panels. (Correct answer)
- Using only ENERGY STAR certified appliances and lighting.
Correct answer: Incorporating on-site renewable energy generation, such as solar panels.
A HERS Index of 0 represents a Net Zero Energy Home, which means the home produces as much energy as it consumes over a year. While airtightness, high insulation levels, and efficient appliances are crucial for reducing consumption, achieving a score of 0 is only possible by offsetting the remaining energy use with on-site renewable power generation.
Question 4: Which of the following components is a fixed assumption for BOTH the HERS Reference Home and the Rated Home in an energy model, ensuring a fair comparison of the building envelope and systems?
- Window efficiency (U-factor and SHGC)
- Duct leakage rates
- HVAC system efficiency (SEER/HSPF/AFUE)
- Geographic location and climate data (Correct answer)
Correct answer: Geographic location and climate data
To create an accurate relative comparison, the HERS rating methodology (ANSI/RESNET/ICC 301) specifies that the Rated Home and the HERS Reference Home must be modeled with the exact same location, climate data, orientation, and geometry. The efficiency of components like windows, insulation, and mechanical systems are then compared against the Reference Home's standard specifications.
Question 5: A HERS rating is performed on two identical homes built side-by-side. Home A has no on-site power generation and receives a HERS Index of 52. Home B has a photovoltaic (PV) system that meets 100% of its predicted annual energy consumption. What would be the HERS Index for Home B?
- 52
- 100
- -48
- 0 (Correct answer)
Correct answer: 0
The HERS Index accounts for on-site power production. Since Home B is identical to Home A in terms of its consumption (HERS 52), adding a PV system that meets 100% of that consumption will offset it entirely, resulting in a Net Zero Energy Home, which is defined by a HERS Index of 0.
Question 6: The Energy Rating Index (ERI) is an optional compliance path in many modern energy codes. What is the relationship between the ERI and the HERS Index?
- The ERI is a federal standard, while the HERS Index is a state-level program.
- The ERI and HERS Index are unrelated rating systems with different scales.
- The ERI score is calculated by subtracting the HERS Index from 100.
- The ERI is calculated using the same methodology as the HERS Index, as defined by the ANSI/RESNET/ICC 301 standard. (Correct answer)
Correct answer: The ERI is calculated using the same methodology as the HERS Index, as defined by the ANSI/RESNET/ICC 301 standard.
The Energy Rating Index (ERI) path in the International Energy Conservation Code (IECC) uses the HERS Index methodology, as defined in Standard ANSI/RESNET/ICC 301, as its basis for demonstrating compliance. A home must achieve an ERI score equal to or lower than the target set by the code for that climate zone.
HERS HERS Index and Ratings Questions and Answers 1
A HERS Rater is explaining the HERS Index to a client.
What does a HERS Index score of 100 signify?