HERS Blower Door & Air Infiltration 3

Question 1

The RESNET ANSI 380 standard requires blower door tests to be conducted with interior doors in what position?

Accepted Answer

All interior doors open

Answer

ANSI/RESNET/ICC 380 requires all interior doors to be open during blower door testing to ensure the entire conditioned volume is tested as a single zone.

Question 2

A rater is testing a house with a connected garage. According to RESNET standards, how should the garage be treated during the blower door test?

Accepted Answer

Seal the door between the house and garage and exclude the garage

Answer

The garage is not part of the conditioned space, so the door between the house and garage should be closed (or sealed if leaky) and the garage is excluded from the test.

Question 3

What does the 'n' factor (pressure exponent) indicate in the blower door fan pressure-flow relationship equation Q = C × ΔP^n?

Accepted Answer

The characteristic of the leakage openings (0.5 = large orifices, 0.65–0.75 = typical)

Answer

The pressure exponent 'n' characterizes leakage opening types: 0.5 indicates large orifice-type openings, while values of 0.65–0.75 are typical for residential construction with mixed opening sizes.

Question 4

For HERS rating purposes, what is the primary metric derived from the blower door test that is used in energy modeling software like REM/Rate?

Accepted Answer

ACH50 (air changes per hour at 50 Pa)

Answer

ACH50 is the primary blower door metric entered into energy modeling software for HERS ratings to calculate infiltration's impact on heating and cooling loads.

Question 5

Which HERS Index range is generally associated with a home that achieves less than 3 ACH50 on the blower door test (assuming average efficiency in other systems)?

Accepted Answer

HERS 60–75

Answer

A home with very low air leakage (under 3 ACH50) typically achieves a HERS Index in the 60–75 range depending on other efficiency measures, significantly below the reference home score of 100.

(HERS) Home Energy Rater Certification Practice Test

(HERS) Home Energy Rater Certification Practice Test

HERS Blower Door & Air Infiltration 3