HERS Diagnostic and Field Testing 2

Question 1

When performing a duct leakage test, which metric is used to express total duct leakage in RESNET standards?

Accepted Answer

CFM25 total

Answer

RESNET standards express total duct leakage as CFM25 total, meaning airflow in cubic feet per minute at 25 Pascals of pressure.

Question 2

A HERS rater measures duct leakage to outside at 52 CFM25 on a 1,800 sq ft home. What is the duct leakage to outside as a percentage of conditioned floor area?

Accepted Answer

2.9%

Answer

52 CFM25 divided by 1,800 sq ft equals approximately 2.9%, which is the standard way to normalize duct leakage to outside.

Question 3

During blower door testing, what does a high inside-out pressure differential (house more negative than outside) indicate?

Accepted Answer

The fan is depressurizing the house as expected

Answer

When the blower door fan exhausts air, it depressurizes the house, making interior pressure more negative than outside — this is the intended test condition.

Question 4

What is the purpose of a 'duct blaster' test conducted with the air handler fan OFF?

Accepted Answer

To isolate and measure duct system leakage independently from the air handler

Answer

Testing with the air handler off isolates duct system leakage from equipment leakage and measures only the ductwork integrity.

Question 5

Which condition would most likely cause an artificially LOW blower door reading during envelope testing?

Accepted Answer

An open window on the leeward side

Answer

An open window allows air to flow freely, reducing the pressure differential and causing the blower door to read less leakage than actually exists.

(HERS) Certified Home Energy Rating System Rater Practice Test

(HERS) Certified Home Energy Rating System Rater Practice Test

HERS Diagnostic and Field Testing 2