Page 1 of 136
HERS Rater Exam Complete questions and
correct verified answers (detailed answers)
already graded A+
1. Which statement best describes the stack effect in a home?
A) Air movement caused by wind pressure on the building
envelope
B) Air movement caused by temperature difference between
indoors and outdoors ✔
C) Air movement caused by mechanical ventilation systems
D) Air movement caused by duct leakage
Rationale: Stack effect occurs when warm air rises and
escapes through upper leaks, drawing cold air in at lower
levels. Driven by indoor-outdoor temperature difference.
,Page 2 of 136
2. A house has 0.5 ACH50 and volume of 20,000 ft³. What is
the CFM50?
A) 100 CFM
B) 167 CFM ✔
C) 200 CFM
D) 250 CFM
Rationale: CFM50 = (ACH50 × Volume) / 60 = (0.5 ×
20,000)/60 = 166.7 CFM.
3. Which material has the highest perm rating (most vapor
permeable)?
A) Polyethylene sheet (6 mil)
B) Kraft paper faced fiberglass
C) Latex paint on drywall ✔
D) OSB sheathing
Rationale: Latex paint is vapor permeable (perm ~5).
Polyethylene is a vapor barrier (perm <0.1). Kraft paper is
semi-permeable. OSB is low perm.
,Page 3 of 136
4. In a cold climate, where should the primary air barrier be
located?
A) Interior side of insulation
B) Exterior side of insulation ✔
C) Middle of insulation
D) On both sides
Rationale: Air barrier should be on exterior side in cold
climates to prevent condensation within the insulation from
warm moist interior air.
5. What is the nominal R-value of 2×6 fiberglass batt
insulation?
A) R-11
B) R-13
C) R-19 ✔
D) R-30
Rationale: Standard 2×6 cavity fills with fiberglass batt = R-
19 to R-21 depending on density.
, Page 4 of 136
6. Which law governs heat transfer through a building
assembly?
A) Fourier’s Law ✔
B) Ohm’s Law
C) Boyle’s Law
D) Newton’s Law of Cooling
Rationale: Fourier’s Law describes conductive heat transfer: Q
= (k × A × ΔT)/d.
7. A window has U=0.30. What is its R-value?
A) 0.30
B) 3.33 ✔
C) 30
D) 0.033
Rationale: R = 1/U = 1/0.30 = 3.33.
8. Which is an example of thermal bridging?
A) Insulation between studs
HERS Rater Exam Complete questions and
correct verified answers (detailed answers)
already graded A+
1. Which statement best describes the stack effect in a home?
A) Air movement caused by wind pressure on the building
envelope
B) Air movement caused by temperature difference between
indoors and outdoors ✔
C) Air movement caused by mechanical ventilation systems
D) Air movement caused by duct leakage
Rationale: Stack effect occurs when warm air rises and
escapes through upper leaks, drawing cold air in at lower
levels. Driven by indoor-outdoor temperature difference.
,Page 2 of 136
2. A house has 0.5 ACH50 and volume of 20,000 ft³. What is
the CFM50?
A) 100 CFM
B) 167 CFM ✔
C) 200 CFM
D) 250 CFM
Rationale: CFM50 = (ACH50 × Volume) / 60 = (0.5 ×
20,000)/60 = 166.7 CFM.
3. Which material has the highest perm rating (most vapor
permeable)?
A) Polyethylene sheet (6 mil)
B) Kraft paper faced fiberglass
C) Latex paint on drywall ✔
D) OSB sheathing
Rationale: Latex paint is vapor permeable (perm ~5).
Polyethylene is a vapor barrier (perm <0.1). Kraft paper is
semi-permeable. OSB is low perm.
,Page 3 of 136
4. In a cold climate, where should the primary air barrier be
located?
A) Interior side of insulation
B) Exterior side of insulation ✔
C) Middle of insulation
D) On both sides
Rationale: Air barrier should be on exterior side in cold
climates to prevent condensation within the insulation from
warm moist interior air.
5. What is the nominal R-value of 2×6 fiberglass batt
insulation?
A) R-11
B) R-13
C) R-19 ✔
D) R-30
Rationale: Standard 2×6 cavity fills with fiberglass batt = R-
19 to R-21 depending on density.
, Page 4 of 136
6. Which law governs heat transfer through a building
assembly?
A) Fourier’s Law ✔
B) Ohm’s Law
C) Boyle’s Law
D) Newton’s Law of Cooling
Rationale: Fourier’s Law describes conductive heat transfer: Q
= (k × A × ΔT)/d.
7. A window has U=0.30. What is its R-value?
A) 0.30
B) 3.33 ✔
C) 30
D) 0.033
Rationale: R = 1/U = 1/0.30 = 3.33.
8. Which is an example of thermal bridging?
A) Insulation between studs
