HERS Energy Modeling & Rating Systems 3 — Questions and Answers
Question 1: A rater finds that duct leakage to the outside is 8% of system airflow. How does this compare to the ENERGY STAR v3.1 threshold?
- It passes; ENERGY STAR allows up to 10%
- It fails; ENERGY STAR requires 4% or less (Correct answer)
- It passes; no threshold applies to existing duct systems
- It fails; ENERGY STAR requires 6% or less
Correct answer: It fails; ENERGY STAR requires 4% or less
ENERGY STAR v3.1 requires total duct leakage to outside of 4% or less of system airflow capacity for compliance.
Question 2: Which software feature allows a HERS rater to model a home with both a gas furnace and a heat pump operating together?
- Dual-fuel heat pump modeling
- Hybrid heating system input (Correct answer)
- Sequential equipment scheduling
- Parallel load distribution
Correct answer: Hybrid heating system input
A hybrid heating system input in energy rating software allows modeling of dual-fuel configurations where a heat pump and backup furnace operate together.
Question 3: What happens to a home's HERS score if window area is significantly increased without changing window U-factor or SHGC?
- Score always improves due to daylighting benefits
- Score typically worsens due to increased conductive losses and solar gains (Correct answer)
- Score remains unchanged since window properties are constant
- Score improves only in heating-dominated climates
Correct answer: Score typically worsens due to increased conductive losses and solar gains
Increasing window area with the same U-factor and SHGC increases both conductive heat loss and unwanted solar gain, generally raising the HERS score.
Question 4: Under RESNET standards, what is the maximum allowed difference between the rated and confirmed home for a sampled HERS rating to be valid?
- 3 HERS points
- 5 HERS points (Correct answer)
- 7 HERS points
- 10 HERS points
Correct answer: 5 HERS points
RESNET sampling protocols allow a maximum 5 HERS point difference between the sampled reference home and the confirmed homes in the same community.
Question 5: When entering window data into energy modeling software, which property most affects summer cooling loads in a South-facing application?
- Visible light transmittance (VT)
- Solar heat gain coefficient (SHGC) (Correct answer)
- U-factor
- Air leakage rating (AL)
Correct answer: Solar heat gain coefficient (SHGC)
SHGC controls how much solar radiation passes through the window as heat, making it the dominant factor for cooling loads from solar-exposed windows.
Question 6: A HERS rater is modeling a home with an attached garage. How should the garage typically be classified in the energy model?
- As conditioned space since it shares walls with the home
- As unconditioned space outside the thermal boundary (Correct answer)
- As semi-conditioned space receiving partial credit
- As outdoor space with no thermal interaction
Correct answer: As unconditioned space outside the thermal boundary
Attached garages are typically unconditioned spaces; the thermal boundary runs along the walls, floor, and ceiling separating the garage from the living area.
Question 7: Which HERS rating pathway allows a rater to use prescriptive compliance for some components while modeling others?
- Simulated Performance Pathway (Correct answer)
- Prescriptive Pathway
- Performance Pathway
- Equivalent Rating Pathway
Correct answer: Simulated Performance Pathway
The Simulated Performance Pathway allows raters to model actual home performance, combining prescriptive and performance approaches within a single energy simulation.
HERS Energy Modeling & Rating Systems 3
A rater finds that duct leakage to the outside is 8% of system airflow.
How does this compare to the ENERGY STAR v3.1 threshold?