HERS Study Guide 2026
Everything you need to pass the HERS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 HERS Exam Format at a Glance
📚 HERS Topics to Study (21)
✍️ Sample HERS Questions & Answers
1. A heat pump water heater (HPWH) will operate most efficiently when installed in which location?
HPWHs need access to a large volume of ambient air to extract heat efficiently; unconditioned spaces like garages provide a heat source without penalizing conditioned space HVAC loads.
2. What does the term 'thermal bypass' refer to in a HERS field inspection context?
A thermal bypass is any air movement pathway that allows air to flow around insulation, significantly reducing its effective thermal resistance.
3. According to RESNET standards, what are the minimum Quality Assurance (QA) requirements that a HERS Rater's Provider must perform annually on the rater's work?
RESNET standards require that a Rater's Quality Assurance Provider must conduct a file review on at least 10% of the rater's energy modeling files and an on-site field review for at least 1% of the rater's total rated homes each year to ensure compliance and accuracy.
4. What impact does replacing a gas storage water heater with a gas tankless (on-demand) water heater typically have on the HERS Index?
Gas tankless water heaters eliminate standby heat losses from maintaining a hot storage tank, which typically results in higher efficiency and a lower (better) HERS Index.
5. A HERS rater finds duct leakage to outside of 8% of system airflow. Under RESNET standards, how is this reported?
RESNET allows a 10% duct leakage to outside default, so 8% passes the verified leakage threshold.
6. What AFUE rating is the minimum threshold for a gas furnace to be considered high-efficiency under current U.S. energy standards?
A gas furnace must have an AFUE of 90% or higher to be classified as high-efficiency under U.S. standards.