HERS Energy Modeling Software 2 — Questions and Answers
Question 1: In REM/Rate, what does the 'as-built' model represent?
- The home as designed on blueprints
- The home as actually constructed and verified by the rater (Correct answer)
- A projected future energy upgrade scenario
- The reference home used for HERS Index calculation
Correct answer: The home as actually constructed and verified by the rater
The as-built model in REM/Rate captures the home's actual construction details verified through on-site inspection and testing.
Question 2: Which blower door test result is the primary input for air infiltration in most HERS energy modeling software?
- CFM25 at 50 Pascals
- ACH50 converted to ACHnatural via the N-factor method (Correct answer)
- CFM75 at natural pressure
- ELA in square inches
Correct answer: ACH50 converted to ACHnatural via the N-factor method
Most HERS software converts the ACH50 blower door result to ACHnatural using the Lawrence Berkeley National Laboratory N-factor method.
Question 3: What is the purpose of the 'reference home' in HERS Index software calculations?
- To model a code-minimum home for permit purposes
- To establish a baseline HERS 100 score against which the rated home is compared (Correct answer)
- To represent the average US home built in 1975
- To model the home with all proposed upgrades applied
Correct answer: To establish a baseline HERS 100 score against which the rated home is compared
The RESNET-defined reference home establishes HERS Index 100 and is automatically generated by software based on the rated home's geometry.
Question 4: When entering duct system data in REM/Rate, which parameter most directly affects duct leakage modeling?
- Duct insulation R-value
- Duct leakage to outside (CFM25out) (Correct answer)
- Total duct surface area
- Duct material type (flex vs. sheet metal)
Correct answer: Duct leakage to outside (CFM25out)
Duct leakage to outside (CFM25out) directly impacts the energy penalty assigned to the duct system in the energy model.
Question 5: In EnergyGauge USA, what does the 'Loads' output report primarily show?
- Annual utility bill projections
- Peak heating and cooling loads for equipment sizing (Correct answer)
- HERS Index breakdown by component
- Monthly energy consumption by fuel type
Correct answer: Peak heating and cooling loads for equipment sizing
The Loads report in EnergyGauge USA displays peak design heating and cooling loads, useful for HVAC equipment sizing verification.
Question 6: Which software setting must be configured correctly to distinguish between a conditioned basement and an unconditioned crawl space?
- Foundation type and conditioning status (Correct answer)
- Below-grade wall insulation R-value only
- Slab perimeter insulation depth
- Window-to-floor-area ratio
Correct answer: Foundation type and conditioning status
Foundation type and its conditioning status determine how the software calculates heat loss/gain through below-grade assemblies.
Question 7: What happens to the HERS Index when a rater enters a higher window U-factor in the energy model?
- The HERS Index decreases because windows become more efficient
- The HERS Index increases because heat loss through windows rises (Correct answer)
- The HERS Index is unaffected since windows are a small area
- The software automatically compensates by adjusting wall insulation
Correct answer: The HERS Index increases because heat loss through windows rises
A higher U-factor means more heat transfer, increasing the home's energy use and raising the HERS Index.
HERS Energy Modeling Software 2
In REM/Rate, what does the 'as-built' model represent?